Trees and shrubs are a valuable addition to most property, providing beauty, wind protection, shade, wildlife habitat, visual screening, and other benefits. Unfortunately, many landscape trees are not properly planted or cared-for. In this publication we describe up-to-date, research-proven techniques for planting landscape trees and for post-planting care. For a more complete description of selecting and planting landscape trees click here.

Tree Type
Landscape trees and shrubs can be obtained in three basic types: bare-root, balled and burlapped, or container plants. Each type has its own advantages and disadvantages and none is ideal for all situations. With all three types you need to be sure that you have an adequate root system--a good rule-of-thumb is that the root system, root ball, or container diameter or spread should be 10 inches to 12 inches for every inch of stem caliper (diameter at ground-line just above any basal swell). Therefore, a 3 inch caliper tree should have a 30 inch to 36 inch wide root ball as a minimum. Root ball depth is not as critical as width but should be larger for larger trees.

• Bare-Root -- Bare-root plants are dug with no soil around the roots and may only have a few coarse, woody roots attached. They are inexpensive and light weight, but they can be difficult to find and their exposed roots must be kept moist. Bare-root deciduous trees should have a caliper smaller than 2 inches and bare-root evergreens should be very small (less than 2 feet tall). Bare-root trees should be planted only when they are dormant and spring planting is best.
• Balled and Burlapped-- Balled and burlapped (B&B) plants are dug with a ball of soil intact around their roots. The root ball is tightly wrapped with burlap held in place with twine, nails, and possibly a wire basket. More roots are contained in the root ball so transplant shock is reduced. Rough handling, though, can break roots and make them lose soil contact, so handle these trees with care. B&B plants are much more expensive than bare-root trees and are much heavier but generally have a better chance of survival.
• Container Plants -- Trees are sometimes grown and sold in pots of various types and sizes for convenience and to avoid root loss during transplanting. Container-grown trees are normally more expensive and heavier than bare-root but less than B&B. Round pots can cause roots to circle which can cause girdling roots later in a tree's life. Such roots should be cut or straightened at planting time. Container trees should be well-rooted without being root-bound. Also avoid buying bare-root trees that have recently been potted and are not well-rooted. Such trees may transplant well but are more expensive than they are worth.
• Tree Spaded -- A tree spade, a large machine that cuts roots and soil so the root ball can be wrapped, is often used to dig B&B trees in the nursery. Some landscape contractors also move trees to the site and transplant them into a previously dug hole with the tree spade. These trees can be treated similarly to a B&B tree, but take care to make sure that the gap between the root ball and the hole is closed so roots can grow out. Tilling around the root ball, as mentioned under B&B trees, is a good way to ensure good contact between the root ball and soil.

Trees can be obtained from nurseries and garden centers as bare-root stock, balled-and-burlapped stock, container grown, or tree-spaded (not shown).

Tree Planting

• Digging the Hole -- Dig your planting hole much wider than the root ball with sloping sides; a hole at least 3 times the root ball width is best (see diagram). The hole should be just deep enough so the bottom of the root ball can be placed on undisturbed soil and the root collar will be at or above the level of the surrounding soil. The root collar is a flared or swollen area on the trunk where the root system and trunk meet and where the soil contacted the trunk in the nursery. Loosening the soil in the bottom of the hole has been recommended in the past but this lets the heavy root ball settle and sink, causing the tree to be too deep. The sides of the hole may become glazed and smooth during digging if the soil is clayey and moist, making root penetration difficult. If this occurs, roughen the glazed surfaces and open up the soil's pores and cracks by picking at the soil with the tip of the spade or a trowel.
• Placing the Tree -- Place the tree in the bottom of the hole onto undisturbed soil with its stem vertical. Handle the tree by its root ball or container to avoid trunk damage. Never drop the tree or you will loosen the root ball and break roots. Make sure that the root collar is at or above the surrounding soil grade. Be careful because many trees have been coming from nurseries with their root collar actually buried deep in the root ball. Planting such a tree with the assumption that the root collar is at the top of the ball will result in a tree planted too deep. If the root collar on your tree is buried a few (4 to 6) inches deep in the ball, just remove the extra soil on top of the roots and plant. If the root collar is deeper than that consider returning the tree, since much of the root system likely is missing.
  
  Now start to remove packing materials from the root ball. Ropes and wires that surround the trunk or root collar should always be removed or they will eventually girdle the tree. Roots must quickly grow from the root ball into the surrounding native soil for the tree to survive. Though untreated burlap breaks down fairly quickly in the soil, treated burlap and some types of pots break down too slowly to assure good, quick root growth out of the root ball. Therefore, if the root ball or potted root system is strong and firm all packing materials should be removed, including pots, wire baskets, and burlap. If the root ball is broken and loose, remove these materials carefully and only to the extent that you can keep the root ball together. Backfilling as you remove these materials may help keep the root ball intact.
  
  Any burlap or potting material that must be left on should be slit in several places to allow roots to grow through. It is less important but still desirable to remove packing materials left underneath the root ball. Cleanly cut any circling or damaged roots that are exposed at this point to promote good root growth.
  Place bare-root trees with their root collar positioned as mentioned above and with their root system spread out in the flat-bottomed hole or over a shallow mound constructed in the bottom of the hole. Do not bend or kink roots to make them fit. If roots are too long for the hole either dig the hole wider and deeper or, as a last resort, cut off some root length with sharp hand pruners. Also cleanly cut any crushed, torn, or otherwise damaged roots.
• Backfilling -- Fill the hole with the original native soil--this is the soil the tree must ultimately move its roots into in order to survive. Large rocks can be removed when backfilling. Up to 25% by volume of composted organic matter can be mixed in with the backfill soil if it has a very high clay content and is difficult to work. Otherwise use no other soil amendments. Polyacrylamide gels (water absorbing polymers) added to the backfill at planting time have been shown to have no significant effect on tree survival or growth.
  
  Break up large clods as you backfill and pack the soil occasionally to remove air pockets. Pack the soil with your hand or lightly with your foot to avoid over-compaction. Straighten the tree and keep its root collar at the right level as you backfill. Add and pack the soil until it is even with the surrounding soil level and the root collar. If you are purposely planting the tree shallow, mound the soil up to the root collar. No roots should be exposed when backfilling is complete. Water well immediately after backfilling to help settle the soil and remove air pockets. Additional soil can be placed where settling occurs but no packing should be done after the soil is wet.

The planting hole should be shallow and wide to allow for rapid root growth after planting. Planting trees too deep is a common problem.

• Planting With Poor Drainage/Compaction -- Poor drainage can and should be improved if possible by grading or installing drain tiles to carry water away (see diagram). On flat sites or sites with moderate drainage or compaction problems trees can be planted shallow, with one-third or more of the root ball above grade and the backfill soil mounded up to cover the root system. Trees can even be placed on top of the existing, problem soil with their roots surrounded by a mound or berm. Such trees may do well but also may have a fairly small root system and will need more care and attention than trees on better sites.

Where adequate drainage is a problem, either elevate part of the root ball above grade and gradually slope the soil around it (see above) or provide a drain to a lower point (see below).

• Season to Plant -- Trees are best planted when they are still dormant with tight, unopened buds in the early to mid-spring after the soil has thawed. Moderate temperatures and good soil moisture in the spring help trees get established. Fall planting also works well for many species, though watering will be critical if the fall is dry. Summer planting of B&B and container plants can be done successfully, though hot temperatures, dry conditions, and non-dormant trees makes good care especially important and survival less sure. Bare root trees should only be planted in spring while still dormant.

Follow-up Maintenance

• Water thoroughly at planting time and for a year or two after transplanting until a good root system is established. Water not only should be applied to the planting area, but also to the soil surrounding the hole so roots can grow out. Remember, it is possible to over water a tree, especially in poorly drained soils. All landscape trees should be watered regularly during periods of severe drought.
• Do not fertilize at planting time since fertilizers decrease root growth and can cause the crown to outgrow the roots. No hormones, extracts, vitamins or other such formulas have been shown to stimulate root growth or help tree establishment. Fertilizing should only be done after the tree has recovered from transplanting, and then only if needed. This recovery can take two or three years; longer with larger trees.
• Mulch with wood chips or other coarse organic material around the base of newly planted and existing trees to increase root and tree health. Mulch should extend several feet from the trunk (wider is better), should be 3 to 4 inches deep, and should be renewed as it breaks down. Keep mulch a couple of inches away from the base of the trunk to avoid root or trunk decay. Air tight plastic sheeting and rock beds should not be used around trees. Porous weed barriers of woven or matted plastic can provide effective weed control but can be difficult to install and maintain and are not much more effective than an adequate organic mulch layer.
• Stake newly planted trees only where wind is a problem. Guy loosely to allow some stem movement, using canvas strapping or similar materials around the tree to prevent trunk damage; hose covered wire often girdles trees. Remove all staking materials after one or two years. In heavily used areas the presence of a couple of tall stakes may help to physically protect the tree even if no guying materials are used.

Staking varies with tree size. Use one stake for trees up to 2" in diameter (A), two stakes for trees 2-4" in diameter (B), and at least three stakes for trees over 4" in diameter (C). Wires can be used, but materials that contact the trees should be soft and flexible, like webbing or rubber straps.

• If you wrap the trunk of your new tree, wrap corrugated paper or other material from the base to one-half of the way up the trunk, overlapping as you go and using masking tape at the top. Apply wrap in the fall after leaf drop and remove each spring, repeating for no more than two or three years. Do not wrap trees with trunks that will be shaded in the winter. Recent research, however, has shown that wrapping trees may do as much harm as good.

Trunks of newly planted trees can be protected with a special tree wrapping paper. The paper is wrapped in overlapping layers starting at the bottom and working up to the branches.

• Prune dead, diseased, damaged, or rubbing branches at planting time. Do not "head back" at planting time to "balance" the roots and crown, as this only weakens the tree. Branches that are too low or are otherwise poorly located can be removed in a year or two when the tree has had a chance to recover from planting.
• Control weeds by using a wide mulch bed several inches deep and by pulling weeds or using directed sprays of herbicides as needed. Herbicides or weed killers that are taken up by roots should not be used since they may harm the tree. Keep all weed killers off of tree leaves, young bark, and sprouts coming from the tree base.

For More Information
There are many good sources of information, including your local Cooperative Extension office, the library, your local nursery or garden center, or a local arborist. Be sure that your source of tree information is up-to-date and is familiar with the latest research on landscape trees. Much of what was recommended for trees in the past has turned out to be unnecessary or even harmful to trees, so remaining current is very important. For general information related to landscape trees or community forestry contact the Utah Community Forest Council, Box 961, Salt Lake City, Utah 84110-0961.

Some of the drawings in this article are from "Selecting and Planting Trees" published by the Morton Arboretum, Lisle, Illinois, and are used with their permission.