The Entomology and Forest ResourcesDigital Information Work Group

Propagation and Care of LeylandCypress as Christmas Trees

1997. The Entomology and Forest Resources Digital Information Work Group, College of Agricultural and Environmental Sciencesand Warnell School of Forest Resources, The University of Georgia, Tifton, Georgia 31793 U.S.A. BUGWOOD 97-013

http://www.bugwood.caes.uga.edu

Introduction

Leyland cypress (X Cupressocyparis leylandii)is an intergeneric (of two separate genera) crossbetween Monterey cypress (Cupressusmacrocarpa) and Alaska Cedar (Chamaecyparisnootkatensis) that originated in England in 1888.Since that time, many cultivars have beenselected that differ in coloration and growthhabit. Leyland cypress has long been suggestedas a selection for shelterbelt, hedge, andlandscape plantings. Plants will tolerate a widerange of soil types from clay to sand, acid toalkaline. It grows well in full sun, but toleratespartial shade. Growth is best when moisture isadequate and responds well to irrigation, but it isalso drought tolerant and suitable for dry sites.Classified hardy to USDA Hardiness Zone 7(average minimum winter temperature 0o to 10o

F), Leyland cypress is relatively cold hardy andwell suited to out planting throughout the state.

Recently Leyland cypress has shown promise forChristmas tree production because of its fastgrowth, natural form and attractive foliage.Many growers produce saleable trees in four yearon quality sites, and there are few major diseasesor insect pests that affect its growth. Thispublication describes the propagation, trans-planting, and cultural practices for Leylandcypress Christmas tree production based onresearch and observation by the authors. These

practices should provide a good reference pointfor growers interested in producing Leylandcypress Christmas trees. Additional research isongoing at the Georgia Experiment Stationregarding Leyland cypress propagation andculture.

Propagation

Leyland cypress do not produce viable seed, thusthe rooting of vegetative cuttings is currently thebest method for propagation. Selection ofappropriate specimen trees from which to takecuttings is a key first step. Select trees with anacceptable natural Christmas tree form. Culti-vars with lateral branches arising at the base ofthe tree and growing up vertically as tall as theterminal shoot are likely to develop double stemsand should be avoided. Foliage color will alsovary by cultivar. Most growers prefer the cultivar‘Leighton Green’ which has rich green foliage.

Selection of cutting material is critical. The ageof the tree, location within the tree crown, andtime of year are all factors to be considered.Generally, the most successful and consistentrooting is achieved with cuttings taken from treesless than 10 years old, or from new shoot growthon older trees. Cuttings should be 6 to 8 incheslong and show some brown coloration in thelower part of the stem. January, February orMarch are the best months to take cuttings.Rooting may be successful at other times of the

Orville M. Lindstrom1, David J. Moorhead2, and Glen W. Kent3

1Associate Professor-Horticulture Research, Georgia Station.2Associate Professor, Warnell School of Forest Resources, Tifton3Agricultural Research Coordinator I, Georgia Station.

11997. MP 350. Georgia Cooperative Extension Service, College of Agricultural and Enviromental Sciences, The University of Georgia,Athens, GA 30602 U.S.A.

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year, but rooting percentage will be low. Aftercuttings are taken, keep them cool and moist andprocess as soon as possible. Do not let cuttingsheat up by leaving them in the sun or bunchedtogether.

Have the containers prepared so cuttings can berapidly processed. Initial rooting can be done insmall volume containers like 2¼ in. square rosepots, or containers of comparable size providedthey have sufficient drainage. Fill the containerswith a porus rooting media such as a 1:1 peat-perlite mixture. Make a two inch deep hole in themedia to accept the cutting.

Prepare the cuttings by pruning them toapproximately six inches long, and strip theleaves off the bottom two inches of the stem.

Dip the base of each cutting, or groups ofcuttings, into water and then into a rootinghormone powder containing 0.8% Indole 3-butyric acid (IBA).

This is a formulation commercially available forhard-to-root woody plants. Tap off excesspowder, place the cuttings into containers andfirm in place. Quick dips for two to three secondsin an alcohol solution containing 0.3 to 0.8% IBAhave also been successfully used.

Maintain the cuttings in a warm, humidenvironment. A good target temperature tomaintain the cuttings is 68o F. A mist system on atimer, set to deliver 5 to 10 seconds of mist at 4 to5 minute intervals, will maintain high humiditysurrounding the cuttings. A greenhouse is idealfor propagation, but containers can be drapedwith plastic to maintain temperature andhumidity. An alternative method is to fill a one orfive gallon plastic bucket with rooting, media,and stick the cuttings into the media. Be sure toput drain holes in the bottom of the bucket. Then,put several boards vertically on the inside edgesof the bucket and lay plastic over them, creatinga miniature greenhouse.

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Root development can be monitored by carefullyslipping the cutting and media from the container.As soon as roots are visible, begin weeklyapplications of a dilute liquid 20-20-20 fertilizersolution. It will take about three months tosufficiently root cuttings.

Once cuttings have been rooted, they need to betransplanted into larger containers such as six-inch or one-gallon pots. Cuttings transplanted toone-gallon pots generally show better growth.Ground pine bark with coarse sand or acommercial greenhouse soil mix can be used as asoil mix. Two teaspoons of a slow release 18-6-12 fertilizer should be added to the containersafter repotting. Maintain the repotted cuttings ina greenhouse or shadehouse until they are readyfor out planting into the field, in approximately 6to 9 months.

Time of year of out planting to the field can becritical. Generally outplanting is done in thespring after the danger of frost. Some growershave successfully outplanted in the fall, winter,and early spring, while other have lost transplantsdue to killing frost. Plants are most susceptible tofreeze damage when taken directly from thegreenhouse or shadehouse without allowingthem to harden off. Before outplanting, cut backon both water and fertilizer and set plantsoutdoors for lengthening periods of time eachday for a total of one to two months. If danger offrost exists during this hardening off period,cover or return plants to greenhouse orshadehouse to protect them from freezing. Rootsare especially susceptible to freeze damage whilein containers since they freeze more quickly thanwhen they are in the field. Avoid pruning plantsduring this period.

Once Leyland cypress transplants becomeestablished in the field, they exhibit a good degreeof cold hardiness. An outplanting at the GeorgiaExperiment Station in Griffin survived, withoutinjury, when a low temperature of - 8o F wasrecorded on January 21, 1985.

Site Preparation

To achieve rapid and consistent growth, locateplantations on sites with adequate drainage andpreferably loamy soils. Avoid dry sandy soilsunless irrigation can be provided, and poorlydrained soils. While Leyland cypress will toleratepartial shade, keep transplants at least 70 feetfrom large trees along field borders.

It is important to start with a weed free plantingsite. On sites with a heavy grass sod, broadcastspray a contact herbicide over the field in latesummer of the year prior to outplanting. If soilerosion is a concern, lay out planting rows on the

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contour and apply the herbicide in a 4 to 5 footband over the intended planting rows. The grassleft in the row middles will reduce soil erosionand can be controlled by mowing. A spacing of7 X 7 feet (888 trees per acre) will allow ampleroom for uniform tree growth and permit use ofa small tractor for mowing.

Check the field for a traffic pan or hardpan, acompacted layer within the soil profile. This is acommon problem on sites that have been incultivation, grazed, or eroded. The compactedlayer restricts root growth, and with the limitedavailable rooting volume, seedlings are moresusceptible to drought stress. The compactedlayer can be broken up by subsoiling along theintended planting row. Subsoiling should bedone in late summer or early fall when soils aredry to achieve maximum benefit. Avoidsubsoiling if soils are wet. Complete all diskingand harrowing operations before subsoiling.

Soil test in the fall to allow incorporation ofpreplant fertilizers and lime as required (checkwith your County Extension Agent) during sitepreparation. DO NOT fertilize withoutrecommendations based on a soil test. Soilphosphorus levels of 50 pounds per acre andpotassium levels of 100 pounds per acre areadequate. A soil pH of 5.5 to 6.0 is ideal.

To outplant the trees, dig a hole twice as large asthe seedling container. Place the transplantcarefully in the hole and pack soil firmly aroundthe root system, eliminating all air pockets.Poorly packed soil around the root system is acommon cause of transplant death. Aftertransplanting, keep the planting row weed freewith application of appropriate herbicides andmow the row middles.

Leyland respond well to periodic fertilization,especially on sandy soils. A 18-6-10 + minors

fertilizer formulation has been used by manygrowers in the state. Slow-release formulationsproviding nutrient release over a 3 to 4 monthperiod are preferred. For most applications,apply approximately 1 tablespoon of fertilizerper foot of tree height in March and again in lateJune to July. Place the fertilizer beneath the dripline of the tree crown, and be sure thatherbaceous weeds and grasses are controlledaround the trees.

Pruning and Shearing

Leyland cypress may develop into acceptableChristmas trees with very little pruning.However, some pruning is necessary to produceconsistently uniform trees. Leyland cypress hasa natural upright branching habit. Lowerbranches can grow as tall or taller as the centralstem, developing trees with two or more“trunks.” Initial pruning, to remove doublestems and excess leaders, should be done whiletransplants are still in the greenhouse. This initialpruning greatly reduces subsequent fieldpruning.

At the end of the first field session, basal prunethe seedlings to develop a 6 to 8 inch handle atthe base of the seedling. The upswept branchinghabit may preclude basal pruning in later years,as removal of upswept branches from the base ofthe tree may leave large gaps in the crown. Eachspring, remove or prune back any double leadersto favor a single main stem. Use these cuttings toroot next year’s transplants. During the year ofmarketing, more precise shearing of the body ofthe tree may be required to achieve a uniformshape. Most growers find that it takes onlyminor shearing to produce a marketable tree.

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Diseases and Pests

Leyland cypress has few diseases and pestproblems. However, there are several organismsthat have been reported to injure or kill Leylandcypress. Several cases of Bot canker(Botryosphaeria dothidea) have been recentlyreported in Georgia. The fungus causing thisdisease is present at low levels on many nativetrees in Georgia forests. Although this organismdoes not significantly affect native trees, it caninjure Leyland cypress. The symptom of thisdisease is an oozing of yellowish sap-likesubstance on the trunk or branches. Branchesand stem are generally girdled and killed abovethe canker, with foliage characteristically fadingto a gray color and then turning reddish brown.

The disease is apparently stress related, invadingthe tree following wounding, cold, heat, ordrought stress. Higher than usual incidence ofBot canker in the past year may be due todrought stresses experienced over the last fewyears. If this proves to be true, Leyland cypressculture may benefit from irrigation.Bot canker can be controlled, but not eradicated,using the fungicide benomyl. This treatmentrequires application at two week intervalsthroughout the growing season and is quiteexpensive. If the disease is not widespread in theplantation, removal and disposal of infectedtrees by burning should be considered. Otherfoliage diseases can also be controlled withbenomyl applications.

Bag worms have been observed on Leylandcypress. Control involves removal of cases andapplication of an appropriate insecticide. Spidermites may also infest trees causing mottled off-colored foliage. Infestations can be controlledwith insecticides. Consult your CountyExtension Agent for pest identification andtreatment recommendations.

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ATTENTION!Pesticide Precautions

1. Observe all directions, restrictions and precautions onpesticide labels. It is dangerous, wasteful and illegalto do otherwise.

2. Store all pesticides in original containers with labelsintact and behind locked doors. “KEEP PESTI-CIDES OUT OF THE REACH OF CHILDREN.”

3. Use pesticides at correct label dosage and intervals toavoid illegal residues or injury toplants and ani-mals.

4. Apply pesticides carefully to avoid drift orcontamination of non-target areas.

5. Surplus pesticides and containers should be disposedon in accordance with label instructions so that con-tamination of water and other hazards will not result.

6. Follow directions on the pesticide label regardingrestrictions as required by State or Federal Laws andRegulations.

Trade and brand names are used only for information.The Cooperative Extension Service, The University ofGeorgia College of Agriculture does not guarantee orwarrant published standards on any product mentioned;neither does the use of a trade or brand name implyapproval of any product to the exclusion of others whichmay also be suitable.

The Cooperative Extension Service, The University ofGeorgia College of Agricultural and EnvironmentalSciences offers educational programs, assistance andmaterials to all people without regard to race, color,national origin, age, sex or handicap status.

AN EQUAL OPPORTUNITY EMPLOYER/AFFIRMATIVE ACTION ORGANIZATION

MP 350 Revised Dec 1997

Issued in furtherance of Cooperative Extension work,Acts of May 8 and June 30, 1914, The University ofGeorgia College of Agriculture and U.S. Department ofAgriculture cooperating.

Wayne C. Jordan, Director