tab Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson

tabPractical Horticulture 7th edition By Laura Williams Rice and Robert P. Rice, Jr.

© 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458

• Draw a diagram of what can be done to prevent tree roots from invading and damaging paved areas.

OBJECTIVESThe student will be able to…




• Compare and contrast the planting procedures for balled & burlapped versus container-grown plants.

• Diagram how to stake a newly planted tree.• Relate the features of a low-maintenance

landscape.• Assemble a list of pruning tools necessary for

landscape maintenance.• Explain the purposes of pruning.




• Recognize crossing branches, improper pruning cuts, suckers & girdling roots on landscape plants.

• Demonstrate the hand removal of candles for pruning evergreens.

• Draw three outline shapes that are acceptable for pruning of formal hedges to ensure the health of the lower portions.

• Describe the advantages and disadvantages of sprinkler versus drip irrigation.




• List three techniques for water conservation in a landscape.

• Identify and describe four mulches suitable foruse in a landscape.



PLANTING THE LANDSCAPEPLANTING THE LANDSCAPE

• Practices for landscaping vary significantly depending on the region of North America.– Landscapes are planted in spring in temperate zones.

• Plants will be dormant or just starting active growing, andtransplant with minimal shock.

• The ground will be thawed (far North), the temperature relatively cool, slowing transpiration, preventing wilting.

– Fall is the second-best time for transplanting.• Again because of the cool temperatures.

– Summer is the least preferable time for planting as sun &hot temperatures make the wilting problems more acute.

• If container-grown plants are used exclusively, roots will beundisturbed and will grow even in summer.



PLANTING THE LANDSCAPEPLANTING THE LANDSCAPETrees & Shrubs - Bare RootTrees & Shrubs - Bare Root

• Shrubs and trees are sold bare root, balled and burlapped, or container grown.– Selling condition determines price, chances of surviving

transplanting, and the seasons for transplanting.




• Only deciduous plants are sold bare root.– Always dug and sold while dormant.

• Most bare-root plants are sold only in spring.– Occasionally available in fall or throughout winter.

• Bare root is an inexpensive way to buy plants, as they are grown in fields with minimal maintenance.– And simply dug up when the selling season arrives.

• Most mail-order nurseries utilize this selling.– To minimize shipping weight.




• A bare-root plant is more likely to die during transplant than a container-grown one.– Many roots are lost when they are dug from the ground.

• When selecting a bare-root plant, pick the sturdiest plant with the largest root system.– Roots should be covered with or bagged in wood

shavings.

– They be damp to the touch—if they have dried, the plant may be dead.

– If the plant is alive, a green layer will be visible underthe surface if you scratch a tiny area of bark.




• If planting cannot take place for several days, the plant should be left in a shady area with the roots covered with moist soil.– This heeling in prevents drying and the death of the roots.

• At planting time, the roots should be placed in a bucket of water & the tree taken to the planting site.



Figure 13-1 A bare root tree after transplanting.

Organic amendment can be mixed with the soil to makea mixture to refill the hole.

PLANTING THE LANDSCAPE PLANTING THE LANDSCAPE Trees & Shrubs - Bare RootTrees & Shrubs - Bare Root• A hole should be dug large enough

to accommodate the roots easilywithout crowding.– Topsoil should be piled on

a piece of canvas or plasticnext to the hole and notmixed with the subsoil.




• Part of the mixture should be shoveled back into the hole, so when the plant is placed in the hole,it will be sitting at or slightly above its original growing level.

• Any badly broken roots should be clipped off with hand pruners, and remaining roots spread outward in the hole, and covered with soil to ground level.

• A small ridge of soil should be mounded around the planting hole as a basin for water.– The plant should be watered in well, by filling the basin

three or four times.



Figure 13-2 A balled-and-burlapped tree after transplanting.

Because the process involves considerable labor, plants sold thisway are expensive.

PLANTING THE LANDSCAPEPLANTING THE LANDSCAPETrees & Shrubs - Trees & Shrubs - Balled-and-Burlapped

• Balled and burlapped refersto trees and shrubs grownin a field but dug tokeep a ball of soilaround the roots.– Both evergreens &

deciduous plantsare balled andburlapped.




• Because the digging disturbs only part of the roots, balled-and-burlapped plants usually transplant successfully.– Provided the ball remains moist, and proper planting

procedures are used.




• Hole and soil preparation is basically the same as for bare-root plants.– However, the hole should be twice as wide as the ball,

and one to one and one-half times as deep.

– Care must be taken when transplanting to preventthe soil ball from breaking.

– Once the plant is in position in the hole, the strings can becut & removed and the burlap peeled back from the trunk.

– Plastic burlap should be removed completely, and even ordinary burlap, which may have been treated to preventrotting, is best removed.



PLANTING THE LANDSCAPEPLANTING THE LANDSCAPETrees & Shrubs - Trees & Shrubs - Container-Grown Plants

• Because the root system develops within the container, the plant is disturbed only slightly at transplanting, and moved when the soil is workable.– With a plastic container, the plant can be turned upside

down and will slide out easily with little shaking.

• A planting hole should be at least twice as bigas the container.

• If the plant is root-bound—with roots grown on the outside of the soil ball, encircling it—the roots should be loosened by hand, or cut so they will brace out into the new soil.



PLANTING THE LANDSCAPEPLANTING THE LANDSCAPETrees & Shrubs - Trees & Shrubs - Boxed Trees

• Occasionally, you will see large trees for sale with their roots in boxes.– These may have been container grown, or field grown.

• Boxing is in lieu of balling and burlapping.

• Planting-hole preparation should be the same asfor balled-and-burlapped plants.

• Carefully remove box to avoid breaking the soil ball.– The tree should be turned on its side and the bottom of

the box removed.

– Using a board as an inclined plane, the box shouldthen be slid onto the planting hole.

– Once in place, the sides of the box can be removedand the hole filled with soil.



PLANTING THE LANDSCAPEPLANTING THE LANDSCAPE Pruning Newly Transplanted Trees and Shrubs

• Pruning new transplants encourages them to develop proper form.– Many times, bare-root plants are sold prepruned,

and need no further pruning until the following season.

• About one-third of the top should be removed at transplant, by removing weaker branches & clipping remaining branches back to one-half to two-thirdsof their original length.– Branches low on the trunk should not be removed,

as the branches strengthen the trunk.



PLANTING THE LANDSCAPEPLANTING THE LANDSCAPEStaking and Wrapping Trees

• Staking may be needed either to anchor the root system of the tree until it becomes established,or support the trunk in an upright position. – Usually for a maximum of 1 year.

• Unless it can be determined that staking is fulfillingone of these functions, it is not necessary.– And will cause weakening of the trunk.



PLANTING THE LANDSCAPEPLANTING THE LANDSCAPEStaking Trees

Figure 13-2 A balled-and-burlapped tree after transplanting.

For root anchorageof bare-root trees,two short stakes(about 1 to 1-1/2 ft) should be insertedon opposite sidesof the trunk.



PLANTING THE LANDSCAPEPLANTING THE LANDSCAPEStaking Trees

• The tree should be secured to each stake with strips of rubber, cloth, or wire, covered with a section of garden hose.– Uncovered wire, rope, or twine is not recommended, as

friction will cause it to rub off the tender bark.

• Trees that require trunk support should be staked as low as will allow them to stand upright under calm conditions.– Stakes should be positioned on opposite sides of

the tree and the trunk tied to the stakes at a singlepoint near the top.



PLANTING THE LANDSCAPEPLANTING THE LANDSCAPEWrapping Trees

• Wrapping involves twining tree-wrapping paper, vinyl, or burlap secured with twine around a tree trunk from the base to the lowest branches.– Wrapping should be

left in place for about1 year after which it should be removed.

Figure 13-3 Wrapping a tree trunk with vinyl tape.



PLANTING THE LANDSCAPEPLANTING THE LANDSCAPEWrapping Trees

Wrapping protects the trunk from sun damage, a problem on trees grown in rows with their trunks shaded by neighboring trees.

It also protects against bark damage from string trimmersused too close to the trunk.

A semi-permanent plastic/metal collar is better in the long run to protect the trunk for many years.

Figure 13-3 Wrapping a tree trunk with vinyl tape.



PLANTING THE LANDSCAPEPLANTING THE LANDSCAPETransplanting GroundcoversTransplanting Groundcovers

• Groundcovers, herbaceous perennials or woody shrubs, are transplanted with a trowel throughouta prepared bed, and watered thoroughly.

• Many herbaceous groundcovers spread by trailing along the surface of the soil, so it is important that soil in a groundcover area be conditioned.– Spaded to at least 12”, with amendment throughout.

• Spacing is determined by economics and how quickly coverage is desired.– Spacing plants 2 ft. apart costs less than spacing 8”

apart, but takes up to a year longer to cover the area.

– 1 ft. spacing gives coverage at a moderate rate/expense.



PLANTING THE LANDSCAPEPLANTING THE LANDSCAPETransplanting GroundcoversTransplanting Groundcovers

It is a water permeable, wovenor felted synthetic material thatis laid over the area to be planted.

Figure 13-4 Planting a groundcover througha landscape fabric will make subsequentmaintenance much easier.

• When landscaping with groundcover, using land-scape fabric to cover the area is a wise investment.

Then holes are cut for each groundcover plant; the plantsare inserted through the fabricfor planting.

The advantages of landscape fabric are permanent, total weed control while still allowing waterto penetrate.

In this regard, it is different from black plastic mulch.



PLANTING THE LANDSCAPEPLANTING THE LANDSCAPEPostplanting Care of the Landscape - WateringPostplanting Care of the Landscape - Watering

• During the first growing season, plant roots occupy only a small volume of soil, and need constant moisture to become established in the new location.

• Slow soaking with a hose is preferred for shrubs and trees, every 7 to 10 days.– Allows all the moisture to be absorbed into the soil and

provides sufficient water to moisten the entire root area.

• Groundcover watering is done by hand or sprinkler.– As frequently as required to keep the soil moist.

• It is advisable to check depth of water penetration with a trowel after watering, digging to the depth of the roots and examining the soil moisture.



PLANTING THE LANDSCAPEPLANTING THE LANDSCAPEPostplanting Care of the LandscapePostplanting Care of the Landscape

• Mulching keeps in soil moisture and prevents weed growth, a problem in newly planted groundcover areas.

• Regular maintenance by pruning, fertilizing, watering, and weed control is a necessity if home grounds are to remain attractive and plants healthy.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCEFeatures of a Low-Maintenance LandscapeFeatures of a Low-Maintenance Landscape

• Landscapes designed to remain attractive with minimal maintenance may include:– Large paved or decked areas that require only occasional

sweeping.

– Raised planters that require less bending for maintenance.

– Groundcover areas in lieu of lawns to eliminate mowing.

– Mulches or groundcovers around all trees & shrubs to eliminate hand trimming, and suppress weed growth.

– An automatic irrigation system where rainfall is insufficient.

– A limited number of carefully placed plants, rather than large numbers of plants scattered through the landscape.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCEFeatures of a Low-Maintenance LandscapeFeatures of a Low-Maintenance Landscape

• Landscapes designed to remain attractive with minimal maintenance may include:– Plants that do not require frequent pruning and do

not drop leaves, fruits, or dead flowers.– Plants that, when mature, will not require extensive

pruning to keep them the proper size.

– Flowering shrubs rather than maintenance-requiring annual and perennial flowers.

– Plants that naturally are disease- and insect-resistantand have been proven to grow well in the locale.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCESoil-Working Tools - TrowelSoil-Working Tools - Trowel

• A trowel is used for digging smallholes for planting bulbs, settingout transplants, and similar tasks.

When purchasing a trowel, check to make sure the handle attaches firmly tothe blade & does not bend.



When tip is pointed to make it easy to push into the soil.

LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCESoil-Working Tools - Soil-Working Tools - Round-Point Shovel

• A round-point shovel is used for digginglarger holes such as for planting treesand shrubs, and for other, generalgarden digging.



Frequently used invegetable gardeningto prepare rowsfor seeding.

Hoes are also used for weeding.

For this purpose, they should be used with a scraping motion that severs the weeds at the soil line.

If used in a cultivating manner, additional weed seeds will be exposed, germinate, and intensify the weed problem.

LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCESoil-Working Tools - Soil-Working Tools - Hoe

• A hoe is used for shallow cultivationof a previously prepared area andwill penetrate the soil up to 4” deep.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCESoil-Working Tools - Soil-Working Tools - Spading Fork

• A spading fork is used to move piles of leaves or refuse, turn compost, and break up large clods in the soil.

• A spading fork is more efficientthan a shovel for these purposes,and moves a greater volume ofleaves or compost with each bite.

A spading fork is distinguished from apitchfork in that it has stronger, flat tines.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCEWatering Equipment - HoseWatering Equipment - Hose

• Many grades of garden hoses are available.– Inexpensive plastic ones are stiff and develop

permanent kinks that restrict water flow.

– Reinforced plastic hoses remain pliable, do not kink,and are lightweight.

– Rubber hoses are the most durable, but are heavy,and expensive.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCEWatering Equipment - Pistol NozzleWatering Equipment - Pistol Nozzle

• A pistol nozzle provides on-off controland can be adjusted to give water invarying intensities, from a strongforceful stream to a gentle mist.

Unfortunately, the directedstream is too forceful for mostwatering, and when emittedat a lower volume, it spraysin a circle and cannot bedirected accurately.

Some gardeners find the forceful stream useful for washing off insects and the mist ideal for watering seedlings.



It often does not provide an ON-OFF control.

LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCEWatering Equipment - Watering Equipment - Flaring Rose (Fan) Nozzle

• The flaring rose nozzle applies a largevolume of water without force and isgood for general overhead watering.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCEWatering Equipment - Watering Equipment - Oscillating Sprinkler

• The oscillating sprinkler is the most adaptable togeneral yard use and can be adjusted to coverany size area by altering the water pressureand the oscillation mechanism.

Because the head movesback and forth, water isapplied over the area ata slow rate, and runoff isless likely than with anon-oscillating type.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCEWatering Equipment - Watering Equipment - Watering Can

• Either plastic or galvanized metal watering cansare acceptable.– Although metal cans last longer, they are heavier

and more expensive than plastic cans.

• The can should contain a removable sprinklerhead so that either a fast volume or a slow sprinkling of water can be applied.



Used for raking leaves, grass, and other lightweight materials.

LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCELeaf RakesLeaf Rakes• A leaf rake can be made of lightweight

metal or bamboo, and has longflexible teeth.



Used for smoothing the soil surface in preparation for seeding a lawn or vegetable garden, removing thatch from the lawn, and other purposes.

LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCEGarden (Bow) RakesGarden (Bow) Rakes

• A garden rake is generally metal, withshort, rigid, widely spaced teeth.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCEFertilizing Equipment - Fertilizing Equipment - Hose-End Sprayer

• The hose-end sprayer attaches to a hose and automatically mixes any liquid concentrateinto the water at dilute strength.

It is used for fertilizing lawns, flowers & othershallow-rooted plants,and for applying certain insecticides.

It is not accurateenough for mostpesticide applications.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCEFertilizing Equipment - Fertilizing Equipment - Root Feeder

• A root feeder works like a hose-end sprayer, proportioning liquid fertilizer into irrigation water.– It is equipped with a long, needlelike tube for injecting

the fertilizer into the root zone of shrubs and trees.



Figure 13-10 Pruning tools.

LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCEPruning Tools - Hand PrunersPruning Tools - Hand Pruners

Hand Pruners are the most frequently used pruning tool.

They will cut branches up to 3/4” in diameter.

It is important to never twist hand pruners when cutting, in an attempt to cut a large branch.

This will pull the cutting blades out of alignment and ruin the pruners.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCEPruning Tools - Pruning Tools - Lopping Shears

Hand Lopping Shears, also called loppers, will remove branches up to about 1-1/2” diameter, cleanly, in a single cut.

Loppers are used on larger shrubs and trees.

Although simple lopping shears are pictured, lever-type shears, and ratcheting shears require less strength to use




LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCEPruning Tools - Pruning Tools - Pruning Saw

A small, curved pruning saw can remove larger branches & is specially designed specially to fit in tight places.

It can substitute for lopping shears, butwill require more labor.




LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCEPruning Tools - Pruning Tools - Hedge Shears

Hedge Shears are needed only if formal hedges are to be maintained




LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCEPower Equipment - Power Equipment - Hedge Trimmer

• An electric hedgetrimmer is essentialto the maintenanceof long sections offormal hedges.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCEPower Equipment - Power Equipment - String Trimmer

• A string trimmer(gas or electric)is used to trimgrass aroundtrees & beside paved areas.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCEPower Equipment - Power Equipment - Power Blower

• A power blower is a mainstay for the maintenance of walkways & other paved areas.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCEPower Equipment - Power Equipment - Edger

• An edger is used to maintain the clean line between turf and nonturf areas.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCEPower Equipment - Power Equipment - Chain Saw

• A chain saw may be necessary to remove large shrubs and trees.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCEPower Equipment - Power Equipment - Power Pruner

• The Power-Pruner, a gas-powered miniaturized chain saw, allows one to reach & remove larger branches without climbing.

A much safer way toremove high branchesthan using a chain saw.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCESafe Use of Power EquipmenSafe Use of Power Equipment - General

• Wear approved eye protection such as safety glasses, goggles, or a facemask.– Objects struck by a lawn edger or string trimmer fly

great distances at great speeds and may cause injury.

• Survey the area and remove sticks, stones, etc.– Keep people and pets at least 50 ft. away.

• Hearing protection may be necessary.– Especially for equipment with a gas (two-stroke) engine.

• Wear protective clothing when using a string trimmer to protect against flying debris.– Long pants, gloves, dust mask & safety footwear.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCESafe Use of Power EquipmenSafe Use of Power Equipment - Edgers/Trimmers

• Lawn edgers should not be used in graveled areas.

• Use a string trimmer only for weeds and grass.– It is not designed to trim shrubbery, climbing ivy, or

other greenery not at ground level.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCESafe Use of Power EquipmenSafe Use of Power Equipment - 2-cycle motors

• For 2-cycle gas/oil engine string trimmers, inspect for loose fasteners, fuel leaks, or acracked or chipped string head before each use.

• Never start or run an engine inside a closed area.– Fumes can cause asphyxiation and death.

• Follow fueling and premixing instructions carefully.– Wipe up spilled fuel quickly and immediately replace

the fuel cap to prevent the possibility of fire.

• In some states, string trimmers have spark arrestors to prevent accidental brush fires.– If you are in a climate where seasonal fires are

common, be aware of this problem.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCESafe Use of Power EquipmenSafe Use of Power Equipment - Blowers

• A dust mask may be necessary, in addition to eye and hearing protection, when using a blower.– Point the blower away from people and pets, & reduce

blower speed temporarily for passing pedestrians.

• Before storing, let the blower engine cool until it is only warm to the touch.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCESafe Use of Power EquipmenSafe Use of Power Equipment - Hedge Trimmers

• Always hold the hedge trimmers with both hands.– Do not trim hedges higher than your shoulders, and

keep both feet on the ground.

– Do not overreach or cut from a ladder, as you maylose your balance.

– Don’t wear loose clothing or jewelry, and keep long hair pulled back when using a hedge trimmer.

– Keep your fingers away from the hedge trimmer blades.

– Never try to clean out trimmings from the blade whilethe trimmer is running.

• Before removing something caught or jammed in the bladesof the trimmer, turn the off-on switch to the “off” position and remove the spark plug wire.



LANDSCAPE MAINTENANCELANDSCAPE MAINTENANCESafe Use of Power EquipmenSafe Use of Power Equipment - Chainsaws

• The most dangerous hazard when operating a chain saw is kickback, which can make the user temporarily lose control of the saw.

• Kickback is caused by the unexpected forceful pushing backward of the saw while running, due to the chain hitting an obstacle, and stopping abruptly.– Some chain saws have an antikickback device on the

tip of the guide bar.




• General cutting procedures:– Never cut with the tip of the guide bar.

– Always keep your body away from the line of cut.

– Always cut with the left arm straight.• If you are right-handed.

– Always cut with a firm grip, with thumbs and fingers around the handle. straight.

• Wear nonslip rubber or leather gloves for better grip.

– Bring the saw to full speed before letting the chain touch the wood, to partially prevent “bucking” or kickback.

– Once the cut is started, cut at a steady speed & pressure.• To avoid being pulled off-balance, do not speed up or slow

down the chain while cutting.




• General cutting procedures:– When felling a tree, plan a retreat from the path of

fall before you start cutting.– When cutting a tree limb under tension, be alert that

the limb may spring back when the tension is released.

– Do not cut from a ladder; it is extremely dangerous.• Use a pole pruner instead.

– Keep the saw regularly serviced.• Professional personnel should perform all service work

other than that specified in the owner’s manual.



PRUNING LANDSCAPE PLANTSPRUNING LANDSCAPE PLANTSPurposes of PruningPurposes of Pruning

• Most people use pruning for size control—to keep plants from growing over windows or walkways, etc.– Not much pruning should be necessary plants are

selected with mature size in mind, and positioned with forethought as to obstructions they might later create.

• Plant health is maintained or improved by removing dead branches and diseased limbs.– Pruning trees when young encourages strong branch

structure, decreasing chances of them storm breakage.

• Removing scraggly branches, clipping off dead flowers, and encouraging bushy, compact growthall improve plant appearance.



Figure 13-17 A well-shaped tree with a central leader form. Notethe even spacing of the scaffold branches down the trunk & wide branch angles. Drawing by Bethany Layport.

PRUNING LANDSCAPE PLANTSPRUNING LANDSCAPE PLANTSPruning Young Trees Pruning Young Trees

Pruning trees at transplant, and the first few years greatly affects strength & health in later life.

In this early period, the tree develops main branches that form the support structurefor the foliage.

Most trees have a central leader, a main upright shoot (leader).

Side branches are called scaffold branches.




Occasionally two leaders develop, causing a fork.

The angle between the two leaders is a potential weakpoint of the tree.

As each leader increases in diameter, it exerts pressure against the other at the base.




Conditions conducive to splitting of the trunk will eventually develop, andin a wind storm, the weightof the leaders can pullthe trunk apart.

On a double-leader, the weaker of the two leadersis removed while the treeis young.

The remaining one will develop normally.




Removal of a double leaderis usually done at the nursery,but removal of excess scaffold branches is usually necessary.

A young tree should ideally haveonly a few branches, which are spaced widely & evenly alongthe trunk.

Numerous small branches areundesirable, as they enlargeand crowd each other as thetree grows.

Scaffold branches should be selected so that they are evenly spaced up the trunk, not growing directly above one another.




Branches growing from the trunk at an angle approaching 90° are preferred, as they are stronger, though many trees have narrow-angled branches when young.




When a double leader or extra branchis removed, the branch always shouldbe cut just beyond the bark ridge or collar, also called the shoulder ring.

Figure 13-18 Bark ridges where healing will occur.

This ridge is an area of raised bark ora ring that surrounds the point at which the branch grows from the trunk.

It contains cells that are a barrier to infection of the cut and proliferaterapidly to close the wound.




• Topping is a practice used by some gardeners in hopes of forming a tree that is full-headed & dense.– The central leader is removed.

– Side branches below the cut grow rapidly, and the ultimate effect is a unnatural-looking, flat-headedtree, with weak branch crotches.

• Topping is not recommended except for modified-central-leader-trained fruit trees.




• When a tree is lion tailed, leaves & smaller branches in the center are pruned off, leaving the inner parts of the tree stripped bare.– This gives an unnatural form, with tufts of leaves at

the branch tips, like the brush at the tip of a lion’s tail.

• Lion Tailing is also not recommended, because it:– Weakens the larger branches.

– Stimulates excess new growth in the inner portionof the tree

– Allow sunlight into the center, which can sunscald bark.

– Alters the foliage balance, which can compromise energyreserves, needed for future growth.




• Limbing up is the removal of branches positioned too low on the trunk, causing hazard/inconvenience.– Necessary, as the height at which a branch originates

is the height at which it remains, permanently.• The trunk does not lengthen & elevate branches.

• Limbing up should be delayed for 3 to 4 years afterplanting, as removal of foliage from a young treewill slow its growth and weaken the trunk.– Once the tree is established, one or two branches can

be removed




• Desuckering is the removal of shoots that grow from the base or lower trunk of trees.– If a tree is grafted, they often grow from vigorous

rootstock.

– Some buds are located too far from auxin-manufacturing buds to be reached by the dormancy hormone.

• Such branches, called suckers, or watersprouts, should be removed by hand pruners as they appear.– If left in place, they give an unkempt appearance, and

use up energy that should be diverted to top growth.

• They are easy to locate because of their vigorous vertical growth, for, if left, they grow until they cross & rub against scaffold branches.



Figure 13-19 Branches that begin to grow inwardtoward the center of the tree should be cut out,as shown. Drawing by Bethany Layport.

PRUNING LANDSCAPE PLANTSPRUNING LANDSCAPE PLANTS Mature TreesMature Trees

• A tree pruned properly when young shouldneed little pruningwhen mature.– Desuckering may be

necessary, along with removal of branches broken by wind orgrowing toward thecenter of the tree.



PRUNING LANDSCAPE PLANTSPRUNING LANDSCAPE PLANTS Mature TreesMature Trees

Figure 13-20 The vertical branch on theright side of the photo should be removed.

Small branches growing close together may rub one another

Smaller or more poorly positioned ones should be cut back to their parent branches to avoid injury tothe bark and grafting together ofthe limbs.



PRUNING LANDSCAPE PLANTSPRUNING LANDSCAPE PLANTS Responses of Trees to Branch RemovalResponses of Trees to Branch Removal

• Wood and bark are made of living, dying, and dead cells with different functions.

• The living parts of wood and bark are connectedin a network called the symplast.– Symplast tissue allows the tree to actively defend

itself against microorganisms.

– When it dies in the natural course of growth of the tree,it becomes protective wood, such as heartwood thathas a static protective function.




• Discolored wood is frequently infected by non-decay-causing fungi.– In the early stages, discolored wood is protective,

but later, as more organisms infect it, the wood maylose its protective ability.

• It can develop soft rot and the secondary layer ofwood can become infected.




• Previous pruning concepts involved the principle that tree wounds “heal.”

• To heal most quickly, it was believed necessary to expose as little heartwood as possible to invasionvia air by microorganisms.– Wound paints were recommended to seal the wood and

theoretically prevent entry of these organisms.• Such paints are ineffective as sealants, & may inhibit healing.




• It is now known that trees react by strengthening old barriers to decay, or forming new barriers.– These barriers enable the tree to resist decay micro-

organisms for a longer time, but not indefinitely.

– A tree survives as long as it can compartmentalizean infection, or restrict spread to a limited volume.

• The tree wound cannot be considered “healing,”but rather the tree is compartmentalizing the infection and growing new tissues to counteract detrimental effects of decay microorganisms.

• This is conceptualized in a model called CODIT– An acronym for Compartmentalization of Decay in Trees.



PRUNING LANDSCAPE PLANTSPRUNING LANDSCAPE PLANTS Responses of Trees to Branch Removal - CODITResponses of Trees to Branch Removal - CODIT

• Decay is defined as the process where ordered wood becomes disordered and no longer functions.– It becomes so depleted of essential elements that few

microorganisms will grow in it—a protective function.

• As microorganisms invade the trunk via branch openings, the tree may compartmentalize the infecting microorganisms.– Over time the trunk wood walls off more symplast, and

space for storage of energy reserve is also walled off.

• Root-rotting fungi slowly kills a tree by this method.– Carbohydrate storage space is continually lost, energy

storage capacity decreases, as does a tree’s ability to defend itself.




• Occasionally, large branches may need to be removed because of disease, incorrect pruning when young, or other reasons.– Such branches, frequently heavy, can break & rip down

the trunk while being sawed off.



Figure 13-21 The three-cut pruning method for removing largebranches, which prevents the branch from tearing down the trunk.


• The three-cut pruning method is recommendedfor removing branches more than 2” in diameter.– The first cut is made under the branch about 1 ft. from

the trunk, and goes halfway through the branch.





• The three-cut pruning method is recommendedfor removing branches more than 2” in diameter.– The second cut is made farther out on the branch and

cuts completely through and removes the branch.





• The three-cut pruning method is recommendedfor removing branches more than 2” in diameter.– The third cut removes the stub down to the bark ridge,

leaving it intact.




• If necessary to remove a stub left due to improper pruning in past years, leave the branch collar.

Only remove the part of thestub extending beyond the branch collar, even thoughthis may leave a considerable amount of stub.

The collar is like the bark ridge, in that it prevents entrance of infection.




• A girdling root results from incorrect initial planting.

Figure 13-22 A girdling root on a young tree.

Signs of damage include flattening of the trunk on one side & dropping of the leaves on the affected side earlier in fall, by deciduous species.

The only cure for a girdling root is to cut it away with a chisel or hatchet.

– If roots are not spread out in the hole, they can enlarge& press against the trunk at, or just below, ground level.

– The resulting pressure halts the flow of water & nutrientsin the trunk, and eventually can kill that side of the tree.




• Many patio trees, weeping trees & some larger shade trees like elm do not havea central leader naturally.– Such trees may split into two

leaders, forming a vase shape, or have all branches arising at one point on the trunk.

Figure 13-23 Vase-shaped tree.

Pruning should include only desuckering and removal ofcrossing & inward-growingbranches.




• Crown Reduction (Drop-Crotch Pruning)—when a tree is mistakenly planted where it will not have adequate growing room, it may be necessary to lower or drop the crown height.– Especially trees under power lines.




• The tallest terminal (vertical) branches are cut back to a large lateral (sideways-growing) branch.– This encourages the tree

to grow outward rather than upward.

Figure 13-24 Branches shown in gray will beremoved to lateral branches to reduce height.

Diameter of the lateral branchto which the terminal branch is removed must be at least one-third the diameter of the terminal branch being cut back.




• Pollarding is a technique forpruning deciduous trees, acommon practice in certain areas of the country.

Figure 13-25 A row of pollarded treesin early spring as growth is just starting.Topping is never an approved practice.

– It restricts the height of the tree, and usually creates a denser head of foliage than the species normally would have.

– Not be confused with topping, which is cutting main branchesoff a tree, to restrict its height,or make the crown fuller.



PRUNING LANDSCAPE PLANTSPRUNING LANDSCAPE PLANTS Responses of Trees to Branch RemovalResponses of Trees to Branch Removal• Pollarded trees have been a part of history for

over 1500 years.– To encourage production of large numbers of whiplike limbs used for animal food, fencing, or firewood.

– It is currently used for a specialized decorative effectin a formal setting or to help keep a tree in a compactand in manageable form.

• Pollarding must be done annually, only on certain species & requires a tree maintenance person.– Most people feel the tree is unattractive when dormant.

– In modern practice, pollarding is usually started afterthe owner notices the tree is beginning to be too largefor the area where it was planted.




• The ultimate objective of pollarding is to develop swollen limb ends of multiple branch collars.– This maintains structure & health while limiting size.

• When the tree is dormant, the main branchesare cut back to a side branch at least one-thirdthe diameter of the main branch.– The initial cut should be slanting, and protect the

side branch’s collar and not cross the bark ridge.

– Heads should be positioned not more than one-thirdthe length along an original branch.




• When the tree begins to grow in spring, buds will sprout below each cut, producing vigorous watersprouts and creating a dense foliage mass.– After 1 or 2 years, the smaller branch can be removed,

as new sprouts should have formed at the wound.

• Sprouts & branches should be cut back to thebasal branch collar, not into the branch wood.– Stubs should not be left when sprouts are removed.

– Sprouts should be pruned back to just beyond thebranch collar.




• Pines are the most familiar needle evergreens.– All characterized by a pyramidal, or “Christmas tree,”

form with a central leader.

• Evergreens generally do not require pruning, except to remove broken or dead branches and occasionally eliminate a double leader.– They may be limbed up above eye level if necessary.

• Evergreens do not branch if cut back to old wood—pruning into woody portions has permanent effects.– The only pruning that can be used to limit size or make

the foliage thicker is the removal of some of the new growth, or candles while the tree still is immature.




Figure 13-26 Pruning a needle evergreenby breaking out the unexpanded candles.

Breaking out a portion ofthe center candle and/or side candles will causethe growth to become shorter and fuller.



PRUNING LANDSCAPE PLANTSPRUNING LANDSCAPE PLANTSPruning ShrubsPruning Shrubs

• To preserve their natural appearance, most shrubs are pruned by either of two pruning methods.– Thinning or heading back.



Figure 13-27 Pruning a shrub by thinning.

Thinning can be done withhand pruners, if stems aresmall, or with loppers, if the shrub is heavily overgrownwith large stems.

PRUNING LANDSCAPE PLANTSPRUNING LANDSCAPE PLANTSPruning Shrubs - ThinningPruning Shrubs - Thinning

• Shrubs are composed clumps of woody stems, or one or more short trunks coming out of the ground.– As oldest stems age & lengthen, they tend to shade out

bottom foliage, and the shrub becomes bare at the base.

– Thinning consists of removing the oldest stems at ground level, shortening the shrub, encouraging new shoots togrow and refoliate the bottom.



PRUNING LANDSCAPE PLANTSPRUNING LANDSCAPE PLANTSPruning Shrubs - Pruning Shrubs - Heading Back

• Heading back is done with hand pruners to remove straggly growth or to limit size.– It consists of cutting twigs or small branches back to a

point where the cut is hidden by the remaining foliage.

Figure 13-28 Pruning a shrub toincrease its density by heading back.



PRUNING LANDSCAPE PLANTSPRUNING LANDSCAPE PLANTSPruning Shrubs - Pruning Shrubs - Heading Back

Figure 13-29 Pruning to an outward-pointing bud.

If possible, stems shouldbe cut back to just abovean outward-pointing budor branch.

This will encourage newgrowth to develop outwardand eliminate crossingbranches.



PRUNING LANDSCAPE PLANTSPRUNING LANDSCAPE PLANTSPruning Shrubs - Pruning Shrubs - Renewal Pruning

• Renewal pruning, to rejuvenate/shorten overgrown shrubs, is done in early spring, before new growth.– Consists of cutting back all branches to stubs 2 - 3” long.

• This forces new growth from dormant buds on the stubs, which can be pruned as needed.– By heading back and thinning to maintain proper size.



PRUNING LANDSCAPE PLANTSPRUNING LANDSCAPE PLANTSPruning Shrubs - Pruning Shrubs - Renewal Pruning

• Renewal pruning is a drastic measure and will make the plant unsightly for at least one season.– As an alternative, half the branches can be removed

the first year and the remainder the second year.

Figure 13-30 Renewal pruning.



PRUNING LANDSCAPE PLANTSPRUNING LANDSCAPE PLANTSPruning Shrubs - Pruning Shrubs - Hedges

• Natural hedges are lines of shrubs planted close together, to create a thick mass of unpruned foliage.– Basically the same as for other shrubs.

• Formal hedges are pruned to a specific shape and require frequent cutting to keep a neat appearance.– Shearing bi-weekly during the growing season is typical.



Figure 13-31 Shapes for formal hedges.

PRUNING LANDSCAPE PLANTSPRUNING LANDSCAPE PLANTSPruning Shrubs - Pruning Shrubs - Hedges

• Selection of correct hedge shape is very important.– Pruning the top narrower than, or at the same width as,

the bottom allows plants to remain full & leafy to the base.– Pruning narrow at the base & wide at the top is incorrect,

as it shades the lower portions, which drop their leaves.

Figure 13-31 Shapes for formal hedges.



PRUNING LANDSCAPE PLANTSPRUNING LANDSCAPE PLANTS Pruning GroundcoversPruning Groundcovers

• Most groundcovers do not require regular pruning to improve their appearance or health.– Occasionally an older bed of groundcover will develop

long, leafless stems, improved by renewal pruning.

• If the area is small, it can be clipped back severely with hand pruners, and hedge shears can be used on woody groundcovers.

• A lawnmower set to cut as far from the ground as possible can be used for large areas during the period of active growth. – While unsightly at first, the area will usually refoliate

in 2 to 3 months.



PRUNING LANDSCAPE PLANTSPRUNING LANDSCAPE PLANTS Pruning Groundcovers - JunipersPruning Groundcovers - Junipers

Figure 13-32 Heading back a groundcoverjuniper to control its spread.

(a) Before pruning. (above)

(b) After pruning. (right)

Note how the branches are layered withlonger branches on the bottom to preventshading out & death of the base of the plant.

Shrub types such asjunipers may requireheading back to control spread.



PRUNING LANDSCAPE PLANTSPRUNING LANDSCAPE PLANTS Timing PruningTiming Pruning

• The time of year at which maintenance pruning takes place will not affect the health of a plant,but early spring is traditional for several reasons.– It is easier to determine which parts of deciduous

plants to remove if the branch structure is notobscured by leaves.

– By pruning before new growth starts, the growing direction of new shoots can be controlled.

• Summer/fall pruning removes poorly placed shootsproduced that season.



PRUNING LANDSCAPE PLANTSPRUNING LANDSCAPE PLANTS Timing PruningTiming Pruning

• Exceptions to the early spring recommendation:– If spring-blooming shrubs are pruned early in the year,

some of flower buds already formed will be cut off.

– Pruning deciduous trees that have sap flow in earlyspring will cause wounds to will exude sap liberally.

• This will not injure the tree seriously, but it is unsightlyand can be avoided by pruning later in the year.

• Light pruning two or three times annually is preferable to severe pruning once a year inorder to maintain an attractive landscape.



PRUNING LANDSCAPE PLANTS PRUNING LANDSCAPE PLANTS Special Shrub-Pruning Techniques - Special Shrub-Pruning Techniques - Espalier

• Espalier is stylized training of a shrub or tree, flat against a wall or trellis.– Usually in a symmetrical branching pattern.

• Not all plants can be adapted to this type of pruning. – Consult references or a nursery worker before espaliering.

• Espalier must be started when a plant is small.– The trunk is tied to the trellis & sites where future

branches are desired are selected.

– Buds or branches closest to these points are tied to the trellis & all others are removed to achieves desired shape.

– Annual pruning is required to remove stray growth,and keep the plant from outgrowing the trellis.



PRUNING LANDSCAPE PLANTS PRUNING LANDSCAPE PLANTS Special Shrub-Pruning Techniques - Special Shrub-Pruning Techniques - Topiary

• Shrubs & small trees trained in pompoms or animal shapes are examples of topiary pruning.– A novelty pruning style, originated

in formal European gardens.

Figure 13-33 Topiary prunedshrub used as an accent.

Topiary can be thoughtof as a combination ofa formal hedge and an espalier.



PRUNING LANDSCAPE PLANTS PRUNING LANDSCAPE PLANTS Special Shrub-Pruning Techniques - Special Shrub-Pruning Techniques - Topiary

Branches are left at selected locationson the trunk, and sheared repeatedlyto encourage fullness.

A topiary should be started while a plant is young, shaping it gradually to its final form over several years.

Figure 13-33 Topiary prunedshrub used as an accent.

One or two topiary plants are sufficientto enhance any landscape.

They can be used effectively in Oriental or modern landscapes and can be purchased pretrained at garden centers.



WATERINGWATERINGWatering FrequencyWatering Frequency

• The goal of watering is to replenish the moisture in the soil surrounding plant roots.– Correct watering of shrubs should give a slow flow

of water at the base of the plant for 20 to 30 minutes.

• Trees should be watered deeply over the entire area covered by the branches.– Roots will be growing throughout the area.

• Established plants, accustomed to sprinkler irrigation are an exception to the deep soaking rule.– The root system of these plants will be shallow, and the

plants will need to be maintained with sprinkler irrigation.




• Frequency with which a plant should be watered depends on age, drought tolerance, and abilityof the soil to retain moisture.

• More newly transplanted trees and shrubs die fromlack of water than from any other cause.– Watering every 7 to 10 days for the first year and

every 2 weeks the second year is advisable.

– After that, irrigation will be needed only during periodsof drought lasting more than 3 or 4 weeks.




• Drought tolerance varies greatly among species.– Some extract minute quantities of water in the soil,

where others in identical conditions would wilt, to thepoint of death.

• Cacti and succulents are the best-known examples of drought-tolerant plants.– Trees with taproots and shrubs native to arid climates

are similarly drought-tolerant.

– They can be used to create a low-maintenance and ecologically sound landscape where natural rainfallis scarce.




• Proportions of sand & clay in a soil greatly affectits ability to retain moisture, and consequentlyaffect the watering frequency.– Soils containing a large percentage of clay will be the

most water-retaining.

– Loams are intermediate, and sandy soils least able to hold water.

• A sandy soil may need watering twice as frequently as a clay, and its moisture-holding capacity can be improved greatly by adding organic matter.



WATERINGWATERINGWatering Techniques - Watering Techniques - Sprinklers

• Sprinklers were the main method of irrigation used for many years in areas lacking regular rainfall.– Their main disadvantage is that they wet all the soil

instead of only that which contains plant roots.

– They also waste water by evaporation from the droplets as they pass through the air.

• Watering by sprinkler can be recommended onlyfor groundcover, lawns, and densely planted areas.

• Sprinkler irrigation should not be discontinued on landscapes established by this watering method.– The plant root systems will have spread throughout the

sprinkler pattern area.



WATERINGWATERINGWatering Techniques - Watering Techniques - Hand Watering

• In landscapes where supplemental watering seldom is required, hand watering with a hose is practical.– The hose can be adjusted to low pressure & moved from

plant to plant every half-hour, or the watering basin made at planting can be filled several times.



WATERINGWATERINGWatering Techniques - Watering Techniques - Leaching

• Leaching is application of a large volume of water to the soil for the purpose of flushing accumulated minerals or fertilizer from the soil.– Sometimes necessary because of an excess mineral

concentration in the soil.

• One way of leaching is to water a plant deeply, wait a few hours, and repeat several more times.– Another method is to leave a hose trickling at the base

of the plant for half a day or so, which uses more water.

• General symptoms calling for leaching are slowed growth, yellowing of foliage, and sometimes wilting.– Even when the soil is moist.



WATERINGWATERINGWatering Techniques - Watering Techniques - Drip or Trickle

• Drip or trickle irrigation advantages include low cost, ease of installation & conservation of water.– Since it applies water only at one spot, germination and

growth of weeds are inhibited—an indirect advantage.




• A typical drip system consists of five major parts: – A filter, a pressure regulator, 1/2” to 3/4” diameter flexible

tubing, and 3/8” diameter microtubing and emitters.

• Water, filtered of particulates, passes through the regulator to lower pressure to about 10% of normal.– Short lengths of the microtubing inserted into the main

lines carry water to emitters at each plant.

– The “drip” & “trickle” names come from the slow flowof water from each microtube—about 1 gal/hour.

• Unlike a sprinkler system, no digging is needed to install a drip irrigation system.– Main lines are laid on top of the ground, covered by mulch.




• Easy to install, trickle irrigation needs no threaded orglued connections, as it operates at low pressure.– Splices are held by self-sealing plastic connectors.

Figure 13-34Putting together a trickle irrigationsystem. Note the small microtubesthat will carry water to each plant.

Microtubes are inserted into the main line by simply making a hole and pushing in the microtube until it fits snugly.




• A main disadvantage of drip watering is a tendency of microtubes to clog with mineral deposits from the water, soil, or algae.– Usually remedied by flushing periodically at high pressure.

Figure 13-35 A microsprinklerhead as seen from above.

Drip systems are used mostoften on tree & shrub plantings, because each individual plantcan have its own microtube.

The system can be adaptedto water groundcover & grassareas by using microsprinklerheads that spray over a limited radius.



WATERING WATERING Water ConservationWater Conservation

• Even when water is abundant, conserving water forirrigating landscape plants should be considered.– There never is enough of this valuable natural resource

to justify thoughtless use.

• Be cautious when using automatic timing devices.– They do not take weather conditions into account, and

may apply water in a rainstorm.

• Frequent checks for water runoff will prevent oneof the most common means of wasting water.



WATERING WATERING Water ConservationWater Conservation

• Improvement of Water-Holding Capacity.– If natural soil in an area has poor water-holding capacity,

it may be improved with the addition of organic matter.

• Prevention of Evaporation.– Much water loss from plantings is by evaporation from

the soil, which can be slowed by use of mulch, and watering in the early morning when the temperature is lowest.

• Use of Proper Irrigation Techniques/Equipment.– Trickle for trees and shrubs.– Sprinkler for lawns & groundcover.



FERTILIZING LANDSCAPE PLANTSFERTILIZING LANDSCAPE PLANTSOrganic FertilizersOrganic Fertilizers

• When buying fertilizer, find products that contain “natural,” organic, or slow-release ingredients.– Improperly applied traditional fertilizers will damage

soil life essential for healthy soils & root systems.

• Natural source fertilizer feeds plants slowly& evenly, resulting in healthier plants.– Strong root systems, without excessive growth.

• Slow-release fertilizers often reduce concentrationof nutrient run-off into ground and surface waters.



FERTILIZING LANDSCAPE PLANTSFERTILIZING LANDSCAPE PLANTSOrganic FertilizersOrganic Fertilizers

• Many homeowners never fertilize trees and shrubs.– Assuming fertilizers are mainly for vegetables & lawns.

• A newly installed landscape, fertilized regularlywill grow much faster than an unfertilized one.



FERTILIZING LANDSCAPE PLANTSFERTILIZING LANDSCAPE PLANTSTiming of Fertilizer ApplicationsTiming of Fertilizer Applications

• The time of year when fertilizer should be appliedvaries with climate, but generally restricted to justbefore, or while a plant is actively growing.– In most parts of the country, fertilizer is applied annually

in spring, so nutrients will be available for the new growth.

• For faster growth, fertilizer could be applied two or three times during the growing season.– For example, on April 1, May 15, and July 1.

• In mild climates such as those found in Florida and parts of California, plants grow continuously.– Fertilizer needs to be applied every 2 to 3 months through

the year to replenish the nutrients absorbed by the plants.



FERTILIZING LANDSCAPE PLANTSFERTILIZING LANDSCAPE PLANTSRates of Fertilizer Application - Trees

• Generally speaking, established trees do not need to be fertilized with phosphorous or potassium.– Unless determined that soil is deficient in these nutrients.

• Their main requirement is nitrogen, applied on a yearly basis by drill-hole or surface application.– Yearly amount of fertilizer recommended for trees is

about 6 lb actual nitrogen per 1,000 sq. ft under the branches.

– Not critical, provided it falls within a reasonable range.



FERTILIZING LANDSCAPE PLANTSFERTILIZING LANDSCAPE PLANTSRates of Fertilizer Application - Shrubs

• Shrubs, evergreen or deciduous, are fertilized in most circumstances at 2 to 4 lb nitrogen annually per 100 square feet of bed area per year.– Using the surface application method.

• The fertilizer can be the same as is used for trees, and can be split into two applications if desired.– The fertilizer should be watered in after it is applied.



FERTILIZING LANDSCAPE PLANTSFERTILIZING LANDSCAPE PLANTSRates of Fertilizer Application - Groundcover

• Groundcover plants will benefit from yearly fertilization in spring using a surface application.– 2-4 lb per 1,000 square feet, watered thoroughly

afterward is advisable

– Either a balanced or a high-nitrogen fertilizer is acceptable.



WEED CONTROLWEED CONTROL

• Weed control is essential, whether chemical or cultural.– Weeds growing in a landscape planting can detract

seriously from its appearance.

– They also compete for available light, water, and nutrition, and will thrive at the expense of the desirable plants.



WEED CONTROLWEED CONTROLCultural Weed ControlCultural Weed Control

• Cultural weed control consists of hand pulling, cultivating with a hoe, using ornamental plants competitively, barriers, mulching, and solarization.

• Hand pulling and cultivation are only effective for controlling annual weeds.– Perennial weeds often break off at the soil line, and grow

back from the roots.

• Cultivation exposes fresh soil & additional weed seeds to favorable germination conditions.– Necessitates repeating cultivation several times a season.

• Mulching is more practical & labor-saving over along period.




• Using ornamental plants competitively can also reduce weed problems.– Planting ornamentals thickly, and using groundcovers

on bare soil areas, deny weeds an opportunity to establish.• They will be crowded out by the desirable plants.




• A barrier of plastic, metal, or concrete can prevent grass from spreading into flower beds and other landscaped areas.– It can also prevent grass from reaching the trunk of a

tree & eliminate nicking the trunk with a mower while cutting the lawn.

Figure 13-36 Plastic edging keepinggrass from invading groundcover bed.



WEED CONTROLWEED CONTROLMulchingMulching

• Mulching is the third cultural weed control.– A layer of mulch excludes light from the soil, checking

the growth of both seeds and existing small weeds.

– A mulch can be any material used to cover the soil surface.

• Mulch is a layer of material such as shredded fall leaves, bark chips, compost, or grass clippings, spread around your plants.

• Mulching plants provides a decorative background for plants, conserves soil moisture, and maintains the soil at an even temperature.– Since it decays in place—it recycles itself!




• You can “grasscycle” a lawn by leaving the clippings on the lawn when mowing.– The clippings rot and release fertility into the soil to feed

the grass, reducing fertilizer needs by 25 - 50 percent.




• Solarization consists of covering well-prepared soil with a thin layer of clear plastic that is left in place for several weeks during warm weather.– Useful technique for nematode, weed & soil pest control,

and may favor development of heat-tolerant beneficial organisms.

• For solarization to be successful, the soil mustbe prepared as for a fine seedbed.– Clods must be broken up, soil thoroughly moistened, and

tightly covered with thin, clear plastic for several weeks.

– The moist-heating process kills many soil pests and can give excellent weed control, though large-seeded weeds may not be controlled completely.



WEED CONTROLWEED CONTROLMulching - Organic MulchesMulching - Organic Mulches• The most popular organic

(plant-derived) mulchesused in landscape plantingsare bark or wood, shreddedor in chunks, and pine straw.

Applied 2 to 3” thick throughout shrub beds & under trees, they give theseareas a neat, rustic appearance.

Being organic, they decompose slowly over a number of years & need renewal occasionally by adding a fresh layer tothe existing mulch.

Figures 13-38 & 39 Shredded wood (top) and chunk wood (bottom) mulches.



WEED CONTROLWEED CONTROLMulching - Organic MulchesMulching - Organic Mulches

• Organic mulches useful for the landscape are not limited to bark.– Rice & cocoa bean hulls, pine needles, and oak leaves are

attractive, but available in only a few areas of the country.

• Corncobs, compost, and grass clippings are also effective, but generally considered unattractive



WEED CONTROLWEED CONTROLMulching - Mulching - Rock Mulches

• Rock mulches can be considered permanent because they do not decompose.– Included are stone materials such as lava rock, marble

chips, smooth stones, and coarse or smooth pebbles

Figure 13-39Lava rock mulch.

Because rock mulches gradually sink into soil, they should be applied over plastic or landscape fabric.



WEED CONTROLWEED CONTROLMulching - Mulching - Rock Mulches

• The disadvantage of rock mulches is that they must be removed & replaced if bed replanting is required.

Figure 13-40 Marble chip mulch. Figure 13-41 Flat stone river rock mulch.



WEED CONTROLWEED CONTROLMulching - Mulching - Synthetic Mulches

• Plastic sheet mulch and landscape fabric are most effective, as they are impervious to weed growth.– Unattractive for use in landscape plantings, they can

be covered with a decorative layer of bark or stone.

– They will also be concealed when used with groundcover shrubs, which spread & hide the material after planting.

• Plastic and landscape fabric generally come in rollsof varying widths and are rolled onto the area to beplanted with edges overlapping.– Plants are transplanted into slits cut through the material,

and edges are covered with soil to hold them firmly in place in case of wind.



WEED CONTROLWEED CONTROLMulching - Mulching - Synthetic Mulches

• Water will run off plastic during rainfall and be diverted through the holes to the plants.– If plastic wider than 3 ft. is used, additional holes

should be made for water penetration into the soil.

• There is no such problem of water penetrationwith a landscape fabric, which is an advantage.– The fabric is also much less likely to tear, which

would permit weed growth through the cut.

– For these reasons landscape fabrics are becomingmore popular than plastic, in spite of higher cost.



END OFCHAPTER

Documents

tab Practical Horticulture 7 th edition By Laura Williams Rice and Robert P. Rice, Jr. © 2011, 2006, 2003, 2000, 1997 Pearson Education, Inc. Pearson