Any tree or shrub that you have just purchased should be considered as a lifetime investment. How well your tree, and investment, grows depends on the type of tree and location you select for planting, the care you provide when the tree is planted, and follow-up care the tree receives after planting. It is not a difficult job, but very important to get right, so the most important considerations are root health, weather, soil conditions and aftercare.
Planting the Tree
The ideal time to plant trees and shrubs is during the dormant season and in the autumn after leaf drop or early spring before budbreak, so generally between October and April. Weather conditions are cool and allow plants to establish roots in the new location before spring rains and summer heat stimulate new top growth. However, trees properly cared for and given the appropriate care during transport to prevent damage, can be planted throughout the growing season. Proper handling during planting is essential to ensure a healthy future for new trees and shrubs, so before you begin planting your tree, be sure you have had all underground utilities located prior to digging. Bare-root and rootballed trees and shrubs are only available in autumn and winter. They should be planted immediately, but if this is not possible, then they can be heeled in until planting is possible. This means temporary planting in the soil to prevent the roots drying out.
If the tree you are planting is balled or bare root, it is important to understand that its root system has been reduced by 90 to 95 percent of its original size during transplanting. As a result of the trauma caused by the digging process, trees commonly exhibit what is known as transplant shock. Trees in containers may also experience transplant shock, particularly if they have circling roots that must be cut. Transplant shock is indicated by slow growth and reduced vigor following transplanting. Proper site preparation before and during planting coupled with good follow-up care reduces the amount of time the plant experiences transplant shock and allows the tree to quickly establish in its new location.
Plants will not grow where soil contains too little air, insufficient nutrients or where soil moisture is either too much or too little. Pre-planting soil preparation should aim to improve these conditions. Firstly, loosen the soil generally to improve drainage and eliminate compaction and improve background fertility by incorporating organic matter, fertiliser and lime - assess the need for lime with a soil pH test if possible. Improving the soil for a wide area is best practice, so 2-3m (6½-10ft) around the tree. If soils are waterlogged over winter consider installing drainage, or an alternative is to plant on a slight mound, about 25-30cm (10in-1ft) high and 1m (39in) in diameter - excess moisture can kill the finer roots, which become blackened and sour smelling.
Guide to planting
Dig a shallow, broad planting hole. Make the hole wide, as much as three times the diameter of the root ball but only as deep as the root ball. It is important to make the hole wide because the roots on the newly establishing tree must push through surrounding soil in order to establish. On most planting sites in new developments, the existing soils have been compacted and are unsuitable for healthy root growth. Breaking up the soil in a large area around the tree provides the newly emerging roots room to expand into loose soil to hasten establishment.
Identify the trunk flare. The trunk flare is where the roots spread at the base of the tree. This point should be partially visible after the tree has been planted. If the trunk flare is not partially visible, you may have to remove some soil from the top of the root ball. Find it so you can determine how deep the hole needs to be for proper planting.
Remove tree container if necessary - carefully cutting down the sides of the container may make this easier. Inspect the root ball for circling roots and cut or remove them.
Place the tree at the proper height. Before placing the tree in the hole, check to see that the hole has been dug to the proper depth and no more. The majority of the roots on the newly planted tree will develop in the top 12 inches of soil. If the tree is planted too deeply, new roots will have difficulty developing because of a lack of oxygen. It is better to plant the tree a little high, 2 to 3 inches above the base of the trunk flare, than to plant it at or below the original growing level. This planting level will allow for some settling. To avoid damage when setting the tree in the hole, always lift the tree by the root ball and never by the trunk.
Straighten the tree in the hole. Before you begin backfilling, have someone view the tree from several directions to confirm that the tree is straight. Once you begin backfilling, it is difficult to reposition the tree.
Fill the hole gently but firmly. Fill the hole about one-third full and gently but firmly pack the soil around the base of the root ball. Then, if the root ball is wrapped, cut and remove any fabric, plastic, string, and wire from around the trunk and root ball to facilitate growth. Be careful not to damage the trunk or roots in the process.
Fill the remainder of the hole, taking care to firmly pack soil to eliminate air pockets that may cause roots to dry out. To avoid this problem, add the soil a few inches at a time and settle with water. Continue this process until the hole is filled and the tree is firmly planted. It is not recommended to apply fertiliser at the time of planting.
Stake the tree if necessary. If the tree is grown and dug properly, staking for support will not be necessary in most home landscape situations. Studies have shown that trees establish more quickly and develop stronger trunk and root systems if they are not staked at the time of planting. However, protective staking may be required on sites where lawn mower damage, vandalism, or windy conditions are concerns. If staking is necessary for support, there are three methods to choose among: staking, guying, and ball stabilising. One of the most common methods is staking. With this method, two stakes used in conjunction with a wide, flexible tie material on the lower half of the tree will hold the tree upright, provide flexibility, and minimise injury to the trunk. Remove support staking and ties after the first year of growth.
Mulch the base of the tree. Mulch is simply organic matter applied to the area at the base of the tree. It acts as a blanket to hold moisture, it moderates soil temperature extremes, and it reduces competition from grass and weeds. Some good choices are leaf litter, pine straw, shredded bark, peat moss, or composted wood chips. A 2- to 4-inch layer is ideal. More than 4 inches may cause a problem with oxygen and moisture levels. When placing mulch, be sure that the actual trunk of the tree is not covered. Doing so may cause decay of the living bark at the base of the tree. A mulch-free area, 1 to 2 inches wide at the base of the tree, is sufficient to avoid moist bark conditions and prevent decay.
Provide follow-up care. Drought stress is common with newly planted trees and shrubs. Even in a cool, wet summer, the rain rarely replenishes soil moisture stores fully. The soil may be dry around the roots even when the surface appears moist. Keep the soil moist but not soaked; overwatering causes leaves to turn yellow or fall off. Water trees at least once a week, barring rain, and more frequently during hot weather. When the soil is dry below the surface of the mulch, it is time to water. Continue until mid- autumn, tapering off for lower temperatures that require less frequent watering. Dry, windy conditions are especially likely to lead to water shortages. With experience, it is possible to detect the dull, lifeless foliage indicative of drought stress but by then the tree has already been damaged.
Pruning & Weeding
Other follow-up care may include minor pruning of branches damaged during the planting process. Prune sparingly immediately after planting and wait to begin necessary corrective pruning until after a full season of growth in the new location.
Weeds, lawns and other vegetation intercept water before it reaches the roots of newly planted trees and shrubs, so keep a vegetation-free circle at least 1.2m (4ft) in diameter around the plant for its first three years to help avoid this problem. The circle can be kept weed free through hoeing or use of contact or systemic weedkillers. Laying mulch over this circle is also helpful, although take care to leave a collar of 10cm (4in) around the woody stems that is free of mulch, to prevent the risk of rotting the bark.
Planting too deep is a common cause of tree death. Aim to plant at the same depth that the tree was growing in the nursery. Poor establishment and brown leaves are also sometimes encountered after planting.