Vegetable Garden

Rich Marini

Department of Horticulture

Penn State University

Unit 1: Garden Planning (Let’s Plan)

• Preparing for a Vegetable Garden• Making the most of the Garden Space

Preparing for a Garden

• Develop plans in February• Select a site – avoid shade, poor soil, wet

and low areas, and walnut trees• List the vegetable species & varieties –

consider season• Decide how much to grow – how will

produce be used• Make a planting map

Planting Map (24’ x 50’)

spinach (3/20) lettuce(3/20) radishes (3/20)

Onions (4/1)

gr. beans (4/15) gr. beans (5/8)

carrots (4/15) peppers (5/15)

corn (4/15) corn (5/1) corn (5/15)

corn (4/15) corn (5/1) corn (5/15)

corn (4/15) corn (5/1) corn (5/15)

North

melons pumpkins

2’

2’

3’

3’

6’

3’

4’

Planning suggestions

• Put vine crops on the edge• Plant 3 rows of corn for pollination• Put tall plants on north side• Plant small amounts several times to

extent the harvest season• 1,000 sq. ft. takes about 1 hr per week of

care

Other considerations

• Rather than rows, can plant broadcast (no rows), but rows are easier to care for

• Consider equipment size for row spacing• Double crop to use space efficiently –

Harvest radishes, peas, lettuce early then plant late-season crops in same space (peppers, beans, summer squash)

Develop a Garden Calendar

• January – look at seed catalogues• February – Order seeds• March – Plant peppers indoors, test soil• April – plant early season crops• May – Sept. – grow garden• Oct. – clean up garden

Unit 2. Planting a Garden

• Understanding soils – soils provide support, water, and mineral nutrients

• Soil is composed of sand, silt, clay and organic matter

• Soil has living organisms – worms, insects, fungi, bacteria: some are pests, some are beneficial

• If too much clay, add organic matter

Soil Chemistry

• Soil pH should be slightly acid (6.0 – 6.8)– Too low: macronutrients are deficient– Too high: micronutrients become toxic

• Macros: N, P, K, Ca, Mg• Micros: Fe, Cu, Mn, B, S, Zn• Most soils have enough of everything

except N,P,K – complete fertilizer

Soil Physical Characteristics

• Sand – large particles, good for water drainage

• Clay – very small particles, holds lots of nutrients, hard to dig, poor water movement

• Silt – intermediate size, water moves slowly

• Organic matter – holds water and provides nutrients and supports micro-organisms

Buying plants & seeds

• Buy current season’s seeds• May have to order unusual varieties• Look for disease resistant varieties• Buy good-quality plants – look for new

shipments – avoid yellow or wilted plants

Artificial Soil Mixes

• Fewer disease problems than real soil• Usually contain fertilizer• Some brands better than others• I like “Mirical-Gro”, but others may be good• Usually contain peat, vermiculite & perlite

and fertilizer

Starting Plants Indoors

• Need warm sunny place• Don’t start too early, plants will be pot-

bound and “leggy”• Transplant to pots when about 1.5” tall• Put outdoors as soon as possible

Planting in the garden

• Cultivate the soil and incorporate fertilizer and lime

• Use string to make straight rows• Small seeds are barely covered, plant

large seeds 2 times their diameter in depth• Thin plants to appropriate distance –

follow directions on the packet

Transplanting

• “Harden” plants by growing outdoors for about a week

• Plant at about the same depth as in pot• Remove peat-pot bottom and side• Water• Avoid hot sunny, windy days

3. While You wait – Plant Science

• Seeds – a seed is an embryo, a tiny plant with root parts, a stem, and about 6 leaves. A seed coat protects the embryo

• Have a food supply until there is adequate foliage to produce enough carbohydrate

• Endosperm and cotyledons (specialized leaves) – starch (corn & wheat) or oil (beans). Coconut “milk” is liquid endosperm.

Two kinds of plants

• Monocots: one cotyledons – grasses• Dicots: two cotyledons – beans, apple,

maple, tomato

Seeds and Seedling

Dicot and Monocot Seedling

Dicot Seedling

Cotyledons

True leaf

Conditions for seed germination

• Seeds are living organs• Need Oxygen for respiration to generate

energy from food supplies• Need Water (imbibition) for cell expansion

and for photosynthesis and biochemical reactions

• Proper temperature – 45 degrees for lettuce, 70 degrees for pepper

• Water and air enter through the seed coat and carbon dioxide exit through the coat.

• Some seeds (lettuce) require light (red light) to stimulation of hormones

• If planted too deep, leaves don’t reach light before food reserves are used up.

• Some seeds have hard thick seed coats and must be scarified (stratch the seed coat) to allow water in.

Germination requirements• Seed coats also contain “inhibitors”

and some need to soak to leach out inhibitors.

• Some seeds require a chilling period (vernalization) to break dormancy (apple seeds need 1,000 hrs below 45 degrees F)

• Hormones (gibberellins) may overcome dormancy

Common reasons for lack of germination

• Improper soil temperature• Soil too dry• Seeds planted too deep• Seeds washed away• Damping-off disease (fungus)

Basic Plant Needs

• Light• Water• Mineral nutrients• Air (oxygen & carbon dioxide)• Proper temperature

Photosynthesis

• A biochemical reaction in the cells of green tissues.

• Chlorophyll is the green pigment in organelles called chloroplasts

Photosynthesis

• Requires the green pigment (chlorophyll) in the chloroplast within the cell.

• The light cycle requires light for energy . Water is split into hydrogen and oxygen.

• The dark cycle occurs in the dark or light where hydrogen combines with carbon dioxide to form glucose. Oxygen is passed through the stomates.

• Glucose or sucrose transported through the phloem throughout the plant.

Light for photosynthesis

• Chlorophyll absorbs light energy to convert carbon dioxide and water into sugars. Oxygen is also produced. Gases (oxygen, carbon dioxide & water) pass in and out of leaves through small holes called stomates.

Respiration

• Within specialized organelles (mitochondria) in the cells, sugars are converted to energy which is used for plant growth. Oxygen is used and carbon dioxide is produced.

Plant parts - Roots• May store sugars (sugar beet, carrot) or

starch (woody roots, sweet potato)• 2 types of roots

–Primary tap root: long strong roots (some trees, carrots, dandelion)

–Fibrous roots: short thin roots arising from larger roots (beans & tomato)

–Root hairs are extensions of cells on the root surface (epidermal cells). These very small structures absorb most of the water and nutrients.

Root Motion

• Roots normally grow down. They are sensitive to gravity (geotropism).

Stems

• Connect leaves and roots, and supports leaves for light exposure. Similar to a pipe. Water and mineral nutrients move up in the xylem. Sugar solution moves down in the phloem.

• Some stems store food – starch in potato, starch in tree trunks in winter, sugar in sugar cane.

Simplified stem cross-section

Epidermis -

Xylem

Phloem

Longitudinal section of a woody stem

Stem function

• Epidermis – one layer of waxy cells• Phloem – live cells • Xylem – long dead cells lined up end-

to-end to produce a “pipe”• Vascular Cambium – a cylinder several

cells thick between the phloem and xylem. Responsible for diameter increase: produces xylem cells to the inside and phloem cells to the outside

Geotropism

• A plants grow in response to gravity• Positive geotropism – roots bend

toward gravity• Negative geotropism – stems bend

away from gravity• Curvature is caused by unequal

growth on the 2 sides of the axis

Auxin – a plant hormone

• Produced in young leaves, shoot tips (meristems) and seeds.

• Auxin moves with gravity, causes bud dormancy and causes cell elongation

Growing tip

Tomato Gravitropism

Phototropism

Auxin

Auxin

Motion of stems• Phototropism - Stems bend toward light.

Auxin is destroyed by light, so cells on the dark side elongate and cause bending toward light.

• Auxin produced in the shoot tip moves down the stem and accumulates on the lower side of the stem, so stems bend up.

• Root growth in inhibited by auxin. Auxin accumulates on lower side, so roots grow down

Apical dominance

• Buds actually are short stems with about 6 leaves.

• Auxin moves from the apex down and inhibits buds. Removing the apex (pinching) allows the buds below the apex to grow. This causes branching.

Carbohydrate transport

• Sugars can be used for energy or converted to structural molecules such as cellulose (cell walls), fats and proteins.

• Sugars move from areas of high concentration (leaves) to areas of low concentration in the phloem.

Flowers – modified stems

• At some point buds switch from vegetative to reproductive – environmental cues.

• Flowers are reproductive structures and attractive insects.

• Pollen produced on anthers is transferred to the stigma, then germinates and grows down the style to the ovary where the sperm fertilizes egg to produce a seed.

Types of flowers

• Perfect flowers have both pistils and stamens (peas, bean, tomato, apple)

• Imperfect flowers are either male or female (cucumbers, melons, squash).

• Some species have male and female plants (ginko trees).

Flower Parts

Fruits• As ovules develop into seeds within the

ovary, the ovary swells and becomes fleshy or hardens to protect the seeds. Fruit helps seeds disseminate.

• Fleshy fruit (squash, tomato, grape) have fleshy ovaries surrounding the seeds.

• Dry fruits have ovaries with thin, dry walls. Corn, wheat, oats and each fruit is a single seed. Beans are dry fruits with a nonfleshy pod containing several seeds.

Seeds

Varieties of bean seeds

Tomato Fruit with Seeds

Bean fruit and seed

How do we make new plants? Plant Propagation

• Sexual – from seeds: Allows a species to survive by perpetuating genetic variation

• Asexual or vegetative – produce new plants from parts of a plant to maintain genetic identify. Produces clones.

Vegetative propagation

• Stems – potato, bulbs• Cuttings – roots can be produced by

leaves or stems• Grafting – join a scion variety onto a

rootstockscion

rootstockMatch up cambiums

Plant Life Cycle

Seeds geminate Plant grows, matures, and flowers Produces fruit and seeds Plant diesAnnuals live 1 year (lettuce, beans)Biennials flower second year, then die

(carrot, onion)Perennials live many years (asparagus)

Plant improvement

• Natural selection: In the wild, individuals within a species differ. Those with characteristics enabling them to survive to reproductive age pass on their genes to the next generation.

• Man has domesticated plants and animals by selecting individuals with the characteristics we want.

Plant breeding• Plant breeding: During the last century we

have controlled pollination to develop hybrids or new varieties with outstanding characteristics

• Examples include high yield, large fruit, different flower colors, disease resistance.

• There is some concern that we have reduced genetic variation too much, new strains of disease may devastate a crop

Biotechnology

• A set of techniques used to study and modify genes.

• Examples– FLAVR SAVR tomato – doesn’t produce the

ripening hormone ethylene, so it can be stored a long time before exposing it to ethylene to cause ripening

– Some corn varieties contain the BT gene for resistance to worms

Genetic Engineering

• Transferring specific genetic material from one organism to another.

• Examples: Put the gene from a firefly into a tobacco plant and the plant glows in the dark.

• Put an antibacterial gene from a moth into an apple tree to make it resistant to bacteria.

Preserving genetic diversity

We want to save genetic variation to use in breeding programs. USDA maintains repositories for major crops; both seeds and plants.

USDA funds plant collecting expeditions to “centers of origin” for major crop species

Interdependence (Ecology)

• All organisms are connected. Some plants rely on animals to transfer pollen and disseminate seed. Some plants rely on fungi to improve root function.

• Animals rely on plants to convert solar energy (sun light) to chemical energy (sugars)

Human impact on ecology

• Acid rain is killing the eastern forest• Ozone, from car emissions, injures

some plant species• Pesticides and other chemicals may

injure non-target organisms• Global warming may alter the

distribution of organisms and agricultural productivity

Hydroponics• We can provide support and nutrients

for plants without soil• Commercial greenhouse tomatoes

are often grown hydroponically in shallow trays of flowing water containing fertilizer.

• Most greenhouse crops are grown in soiless mixes of sand, perlite, vermiculite, and peat

Unit 4. Garden Care

• Soil fertility – At least 2 months before planting contact local Extension office for soil testing kit. Fertilize & lime according to recommendations.

• Apply lime to raise soil pH and reduce acidity (about 6.2 to 6.8)

• Apply complete fertilizer to provide nitrogen, phosphorous, potassium

Organic Matter

Organic matter provides nutrients and improves soil structure and water holding capacity. Also encourages many soil organisms – worms, insects, fungi, bacteria

Sources – compost, manure, bone meal

Garden Equipment

• Hoe, rake, trowel, watering can, hose, short stakes and string to mark rows, long stakes for supporting plants, hot caps, sprayer, tiller

• Pesticides – read the label– Store locked up– Leave in original container– Avoid freezing or hot environments

Frost

• Site selection – avoid low areas because cold air is heavier than warm air and flows down hill just like water.

• Tender plants, such as tomato, peppers, squash are killed at about 30° F

• Cool season crops, such as cabbage, broccoli tolerate a light frost (27° F), and carrots, beets, lettuce tolerate 22° F

Frost protection

• Cover plants with hot caps, newspaper tents, or mulch with straw

• Overhead irrigation• Late season frost – harvest as much

as possible before the frost

How does irrigation work?• As water freezes it releases heat. Ice

provides little insulation, so irrigation must continue to freeze until the temperature increases above 32° F and all ice has melted

• Don’t irrigate when due point is low and there is wind because evaporation requires heat and heat will be removed from plants

How do hot caps work? Greenhouse effect

During the day short-wave solar radiation is absorbed by soil and exits the soil at night as long-wave radiation. Hot caps provide a barrier to long-wave lengths which are redirected toward the soil. Frosts are rare on cloudy nights because clouds allow short waves, but not long waves, to pass through.

Managing weeds

• Weeds are plants growing where they are not wanted

• Weeds compete for light, water & nutrients• Best to eliminate weeds when small• Mechanical control – pull by hand, hoe,

cultivation. This must be done every 10 to 14 days depending on rain. Weed seeds can remain dormant in soil for many years.

Mulch to control weeds

• Can use straw, shredded paper, thin layer of grass clippings or plastic

• Also helps conserve water, reduces soil erosion and keeps plants clean

• Apply mulch early, before weeds come up

Herbicides

• Chemicals that control weeds• May control grasses, broadleafs or

both• Pre-emergent herbicides prevent seeds

germination• Post-emergent herbicides kill plants on

contact• Not recommended for home garden

Plant diseases• Infection requires

– Susceptible host plant– Presence of the pathogen– Proper environment for disease

development• Powdery mildew requires hot dry

conditions, and early blight on tomato requires wet conditions

• Viruses spread by insect vectors

Managing plant diseases

• Caused by fungi, bacteria, nematodes or virus

• Select resistant varieties when possible• Encourage quick drying – avoid shade,

control weeds, leave space between plants

Controlling diseases

• Cultural control – good drying conditions, resistant varieties, remove diseased plants

• Fungicides and antibiotics – these are preventative and must be applied before infection occurs. Apply every 10 to 14 days to protect new growth and replace residue washed off by rain.

Diseases of squash

Septoria leaf spotPowdery mildew

Virus

Non-pathogenic problems

• Sunscald heat injury to fruit• Cold growing conditions can cause plants

to turn purple due to poor phosphorous uptake

• Too much fertilizer can burn roots and cause wilting

• Too much pesticide can damage leaves

Insect pests

• Many types of insects can feed on plants.• Grubs (immature beetles) feed on roots• Worms (immature moths) feed on leaves,

fruit, or tunnel into stems (borers)• Maggots (immature flies) feed on fruit &

roots• Beetles, aphids, and true bugs feed on

leaves

Japanese beetle life cycle

Controlling insects

• No resistant varieties, except for genetically modified varieties of corn and soybeans (BT genes)

• Use insecticides to kill insects– Monitor plants every week– Don’t apply until you see pests– Use “soft’ materials that protect nontarget

organisms

Aphids

Corn Ear Worm Life Cycle

Adult Larvae

Pupae

Natural vs. man-made pesticides

• All are poisonous and should be treated with care

• Natural materials usually are broad-spectrum and kill nontarget species, and they must be applied more frequently because they are less residual

• Insecticidal soaps are effective• Many insects are beneficial and we want

to protect them

5. Harvest & storage

• Important to harvest vegetables at proper stage. If many leafy vegetables are left too long, they will produce flowers

• Peppers are ready when they are full size, can wait and harvest them red

• Tomato can be harvested when just beginning to turn red

• Cantaloupes are harvested when stem slips off the melon

Other vegetables

• Zucchini, summer squash, and cucumbers are harvested when fairly small (before seeds enlarge) and need to be harvested every day or two.

• Potatoes are harvested when leaves start to die in late summer

• Onions are mature when leaves fall over

Storage

• Harvested plant parts are living tissues and continue to respire. We want to slow down respiration so the cells remain alive

• High humidity for leafy vegetables – put in perforated poly bags

• Temperature is most important– Most vegetables store well in the refrigerator

(about 40ºF)– Peppers store at about 50ºF

Unit 6: Careers

• Without a college degree– Farm, greenhouse, florist worker– Assistant manager, retail market– Landscape worker

• 2-yr Associate degree in plant science– Assistant superintendent for golf course– Farm & retail store manger– Arborist, flower shop manager

4-yr degree programs

• Crop protection – entomology, plant pathology, weed science

• Environmental sciences• Ag economics - farm management, rural

development• Horticulture, landscape architecture &

landscape contracting• Plant genetics & plant breeding

Careers with B.S. degree

• Teach agriculture and science• Ag. Chemical sales, exterminator• Government agencies (USDA, DEP, EPA)• Manager of farms, retail centers,

nurseries, flower shop• Landscape architect, Landscape

contractor, golf course superintendent• Plant breeder

Careers with M.S. degree

• Research technician with chemical company, university, USDA, private lab

• Plant breeder• Produce wholesale & marketing• International agriculture• Government agencies• Ag sales and marketing• Extension agent• Teach at community college• Public gardens & arboreta

Careers with Ph.D.

• Academia (teach, research, extension)• Ag. Chemical company R&D• International agriculture• Plant breeder• Industrial research – Ag. Chemicals, plastics,

greenhouses • Marketing• Government agencies (USDA, EPA, DOE, DEP,

PDA)

Other considerations

• Rather than rows, can plant broadcast (no rows), but rows are easier to care for

• Consider equipment size for row spacing• Double crop to use space efficiently –

Harvest radishes, peas, lettuce early then plant late-season crops in same space (peppers, beans, summer squash)