Planting Techniques
By Dave Bloniarz, USDA Forest Service

Abstract

Once a site has been chosen for planting a new tree, it is important that careful consideration be given to the actual installation technique in order to ensure the tree?s survival. Since most trees will be transplanted from a nursery setting where they have received scheduled care and nurturing, it is critical to follow proper planting methods to reduce the shock of transplanting and establishment. Whether the planting will be done by community volunteers or hired contractors, it is important to plant the tree correctly, giving it the best chance for a long and healthy life. The following information outlines some recommendations for planting balled and burlapped, and bare root trees.

Techniques for Planting Balled and Burlapped Trees

Using a step-by-step process to plant trees will help ensure that they have an opportunity for survival and healthy growth. According to the International Society of Arboriculture, the root system of a balled and burlapped tree has been reduced by 90?95 percent of its original size. This dramatic shock to the tree?s physiology often results in slow growth and reduced vigor following transplanting. Proper preparation of the site is critical to minimize the rigors of transplanting a tree from a nursery into your landscape.

If possible, prepare the site before you bring in the tree. Keep the root ball well watered and put the tree in a shaded spot until you are ready to plant. In order to measure the proper depth for the planting site, it is necessary to expose the trunk flare on each balled and burlapped tree. The trunk flare is the point where roots begin to branch from the trunk. (The top of the root ball is not always the trunk flare.) Remove the burlap from the immediate trunk area of the tree. Pull back any excess soil around the trunk to locate the trunk flare. Measure the distance from the base of the trunk flare to the bottom of the root ball and dig to that depth. The hole should be at least three times the diameter of the root ball, with the sides of the excavated area at a 30-degree angle.

In addition, you will need to break up compacted soil. The sides of the planting space should not be packed. Leave the bottom of the space firm. Do not amend the soil unless planting in building rubble, or in poor or severely disturbed soils.

When actually planting the tree, it is important to follow these simple steps:

  • Lift the tree into the planting space by the root ball, not the trunk.
  • Balance the tree upright in the center of the planting space.
  • For trees in wire baskets, cut and remove the wire.
  • Cut away strings and burlap or plastic, exposing the root ball. Do not remove soil from the root ball.
  • If the tree is container grown, cut and remove the container.
  • Prune dead or crushed roots and straighten or cut circling roots. Make clean cuts.
  • Begin refilling with soil, watering as you fill to firmly set the tree. Gently tamp the soil.
  • Never plant too deep. The trunk flare should be at grade. Fill with soil up to the tree base just to where the roots begin to branch from the trunk
  • Prune only dead or injured branches. Do not paint wounds.
  • Remove tree wrap, tape, or string on the trunk. Trunks should be wrapped only to protect them in transit to the planting site.
  • Stake and brace large trees, or trees that are planted in a windy, exposed location. Support the tree but allow it to move or sway.
  • Use wide, belt-like strapping attached to two sturdy stakes. Do not use rope or wire through a hose.
  • Mulch lightly and evenly with 2” of composted material to at least the diameter of the crown of the tree. Leave a 3” circle of bare soil around the trunk. Deep layers of mulch can be harmful.
  • Do not plant flowers under the tree.
  • Do not fertilize at planting time.

Improper planting depth and excess mulch are often the cause for predisposing new transplants to not only immediate, but also future, cultural, insect, and disease problems.

Special attention is necessary to ensure that a tree is not planted too deep. Many times a landscape professional correctly plants to the top of the root ball, and sometimes even plants 1–2” high to allow for landscape mulch and a little settling. But balled and burlapped trees are often handled many times between the wholesale nursery and the landscape site. This handling causes the soil within the ball to be pulled up around the trunk. Unless this excess soil is removed down to the stem flare or root collar, trees are likely to be planted 2–3” too deep.

Excess mulch can also decrease a tree’s ability to thrive. The proper use of landscape mulch is to simulate the leaf or duff layer found in the tree’s natural setting, which provides organic matter, increases moisture retention in the soil, and regulates soil temperature fluctuations. Landscape mulches also reduce the growth of weeds and grass, eliminating the potential for mower injury to the trunk. Landscape mulches should never be applied at a depth exceeding the 2–3” layer that occurs in the natural environment and should never touch the trunk.

Excess soil and mulches around the stem and root zone areas decreases the ability of the roots to obtain oxygen. This adversely affects root growth, thus reducing the tree’s ability to collect water and nutrients. Furthermore, excess soil and mulch around the tree’s stem causes the bark to be constantly wet, which can reduce the tree’s cold tolerance, encourage fungal pathogen and insect invasions, reduce incremental growth, and lead to adventitious and girdling roots.

Assuring proper planting depth and maintaining proper mulching practices will greatly decrease future therapeutic maintenance while enhancing the tree’s ability to thrive, thus allowing it to become a beautiful asset to the landscape.<

Fertilization is usually not necessary or recommended at planting time. If it is desired or necessary, use fertilizer that is organic or slow release. Pruning at planting time should be limited to removing only broken or misshapen branches.

Bare Root Planting

Bare root trees are dug and stored without any soil around their roots, which allows for more roots to be saved while transplanting from the nursery to a new planting site. According to some estimates, bare root trees can have up to 200 percent more roots than container trees, depending on the soil type and transplanting method used at a particular nursery. Also, since the soil is left at the nursery, only the tree and its roots need to be handled and shipped, making these trees much lighter and less expensive, and cheaper to transport. Bare root trees are also easier to plant, making this type of tree more appealing to volunteer initiatives, which rely on community members to do much of the physical labor involved in planting trees.

Bare root planting is not without some disadvantages, but with careful planning and scheduling, many of these issues can be easily overcome. The use of bare root trees reduces the window of time available for planting. Once bare root trees have been dug and shipped from the nursery, they need to be planted within 7 to 10 days, depending on the air temperature and weather conditions. Since there is no soil around the root, the small feeder roots and root hairs will dry out and die if left exposed, making it important to plant the tree as soon as possible.

Bare root trees need plenty of soil moisture in order to establish themselves in a new planting location, therefore early spring (before budbreak) and fall (after leaf fall) are the only two possible planting times. Some species may not be available as bare root trees, and some nurseries may not have bare root trees available for retail sale at all.

The best techniques for bare root tree planting are as follows:

  • Use any technique you can to reduce the time the tree roots are bare.

  • Order 1½–2” trees to be dug within 24 hours of your arrival; otherwise, be sure they have been stored in a cool place.

  • Have spring trees dug in late March to early May and fall trees dug in mid-October to late November.

  • If possible, dip tree roots in a hydrogel (a synthetic water-absorbing compound) slurry or muddy water, then store them in large, pleated plastic bags until planting.

  • If no hydrogel is used, soak the tree roots in water for 12–24 hours before planting.

  • Keep the trees covered, shaded, and moist until actual planting.

Sources

The materials contained in this abstract were adapted from the following publications:

New Tree Planting.  1995.  Informational brochure produced by the International Society of Arboriculture, P.O. Box 3129, Champaign, IL 61826-3129.  Available online at
http://www2.champaign.isa-arbor.com/consumer/planting.html

Bare Root Tree Planting. 1998. Informational brochure produced by Cornell Cooperative Extension of Monroe County, New York, and Community Forestry Education Project.  Available online at http://www.cce.cornell.edu/monroe/cfep/factsheets/24bareroottreeplanting.htm

Planting Trees in Designed and Built Community Landscapes: Checklists for Success. 1998. Informational brochure by Mary K. Reynolds, Urban Forester, State of New Hampshire Department of Resources and Economic Development and H. Sharon Ossenbruggen, Urban Forester, USDA Forest Service State and Private Forestry,Northeastern Area.   Available online at http://www.na.fs.fed.us/spfo/pubs/uf/plant_trees/planting_trees.htm