When to Plant
Bare root deciduous and evergreen trees and shrubs can be planted in either the spring or fall. Containerized and balled and burlapped plant stock can be planted at anytime during the growing season if they are kept well watered.
Deciduous plants are best planted in the spring after the frost is out of the soil until the new foliage is partly unfurled. In the fall deciduous plants can be planted any time after the leaves begin to change colour until the ground freezes.
In the spring evergreen plants are safely planted (when well watered) until about 4 weeks after deciduous trees have leafed out. Fall planting of evergreens should be completed by mid-September so the plants are able to develop new roots before the soil freezes.
Planting
To prepare the soil for planting a tree or shrub it is most important to dig a wide hole. This loosens and aerates the soil providing a better environment for new root growth. The hole should be at least 45-60 cm larger in diameter than the root ball. The depth of the hole should be such that the root ball is covered by about 2.5 cm of soil.
Once the hole has been prepared remove any plastic from a balled and burlapped plant and the container from the container stock. Remove the bottom and break the sides of peat pots in several places. Do not allow the roots of any planting stock to dry out during the planting process as this will kill the roots.
After placing the plant in the hole, remove as much of the burlap as possible from around the root ball by cutting it off or spreading it out in the hole. When filling the hole with soil, work the soil around the roots or soil ball and firm the soil around the roots to avoid air pockets. Finish filling the hole and tread the soil down firmly, leaving a slight disc-like depression around the base of the plant to catch extra moisture. Water thoroughly.
Plants must be watered thoroughly every three to five days during the growing season if there is insufficient rainfall.
Soil Amendment
Organic amendments added to the planting hole do not usually help and often hinder the growth of the plant. In an amended planting hole the roots of the plant prefer to remain within the boundaries of the original planting hole and consequently the plant becomes root bound.
For best results if the soil is very poor, amend the soil over the large area where the roots will develop; otherwise drought or saturated conditions could prevail in the amended soil. These stress conditions make it very difficult for plants to grow well.
Clay soils can be amended in several ways to improve the soil structure. Adding organic matter loosens the soil, but because it breaks down rapidly it only provides a temporary change. Adding coarse sand in the proportion of about 1 part sand to 2 parts soil causes a permanent, beneficial soil change.
Drainage
There are several ways to treat drainage problems in soils. A percolation test will indicate if the soil is properly drained. Dig a hole 30-40 cm deep, and fill with water several times during the day to wet it. Fill the hole again in the evening; if the water has not drained in 24 hours then the soil is imperfectly drained.
The easiest way to deal with imperfectly drained soils is by choosing plants that tolerate poor drainage, or plants can be planted in shallow mounds above the existing grade. A more effective but more difficult way to deal with imperfect drainage is by installing a tile or gravel drainage system.
Mulching
Organic matter is better used as a surface mulch than as a soil amendment. A mulch applied about 8-10 cm thick has many advantages: it insulates the roots of plants from the summer heat and reduces moisture loss. It also reduces the compacting effect of rainfall on the soil, reduces runoff and allows for the slow percolation of water into the soil.
Fertilizing
Fertilizer added to the planting hole may burn the roots of the tree. It is not usually necessary to fertilize at planting time but a water soluble fertilizer used as directed may help the tree get started.
Staking trees
Only stake trees when necessary. A young plant may require staking on certain light soils, on windy sites, or when the tree is quite tall in proportion to the size of the soil ball.
For proper trunk development a tree needs to be able to move in the wind (Fig.1), therefore it should be staked as low as practical for the size of the tree, with flexible stakes (e.g. 1.25 cm concrete reinforcing rod). Stakes should be located outside of the area disturbed for planting. If the tree will be staked only three to six months a length of wire through a rubber hose is adequate to hold the tree. The preferred method if the tree will be staked for a year or more requires eyescrews (the size should be proportionate to the diameter of the tree). A wire is attached to the stake and the eyescrew. These screws can be left in the tree when the stakes are removed as the tree will eventually callus over them. Removal of the screws may actually cause more damage to the tree by allowing the entrance of decay organisms.
A second staking method requires only one stake and a tree saddle to hold the tree. For this method drive a 2-3m wooden post or iron rod into the planting hole prior to planting to avoid the possibility of severing a major root with the stake. The tree is planted then attached to the stake with a tree saddle.
The first few years of development play a major role in the long term health of plants. By following these few guidelines beautiful and healthy trees can be grown to last for many years.
Figure 1 Staking trees.
Whitcomb, C.E. 1986 Landscape Plant Production, Establishment and Maintenance, Laubark Publications, Oklahoma, U.S.A.
1988