Special care is needed for newly planted trees and shrubs. During the first year, attention to watering it is essential. Root systems of plants grown in a nursery have been watered daily to maximize health and growth and in general plants have been spoiled by constant attention to their needs!
During the heat and dry spells of summer and autumn, providing that consistent watering to keep the whole root mass damp will keep the plant from going into shock. In other words, to keep the plant from going into stress we need to water each plant for five to ten minutes directly at its base and allow the water to sink in deeply by using a slow flow, so it does not run off and get wasted.
The root mass is still small at this point and will be for a year or two. This watering can also be done by putting the tap to a trickle, letting the hose end sit at the plant base and then moving it every 20 min to the next plant which ensures complete percolation to the full depth of the root ball by water.
Because the root mass gets fully damp this way, then on hot days during the summer you can water every other day and in spring and autumn every third or fourth day. So long as the roots remain damp it will be fine, but it must not dry out. Putting mulch or compost over the surface will help maintain the moisture level in this first year and it will also cool the soil which encourages root expansion—roots do not do well in soils which are baked from the heat of the sun.
A key benefit of planting on a berm is that the plant will not be drowned as happens frequently to trees and shrubs planted in pits where drainage is often poor or non-existent. We have known for a long time that one of the biggest killers of young trees planted in city soils is drowning. However, when planted ‘on high’, water drains out at the base and is replaced by aeration which is just as essential for root health, encouraging them to rapidly explore the surrounding soil and become self-sufficient and stable.
If a newly planted tree has a large canopy, then it will need a stake to support it during strong winds, but the support needs to be removed after the first year or two. When the winds cause a tree to move, the plant recognizes the need to focus new growth in both root expansion and trunk thickness, so as to compensate for being grown in the sheltered circumstance of its original home—the nursery. This movement is important in helping the young plant establish quickly. One of the additional advantages of planting young trees (less than five years old) is that staking is necessary only occasionally and this is a considerable cost saving.