When the best time to plant a tree is may be a simple question, but the answer is somewhat complicated. The successful outcome of planting a tree by seed or transplanting a seedling is influenced by the date it was planted. Determination of the best time is related to the climatic conditions at the site. Observing the natural rhythm of native tree growth provides solid and reliable guidelines. Most tree species exhibit an annual cycle of growth and reproduction, linked to climatic factors of temperature and precipitation, while some tropical or subtropical trees bear flowers and fruits continually throughout the year. This subject is best addressed by considering both the best planting times in the middle latitudes and subtropics, and whether you are planting seeds or transplanting seedlings or saplings.
In the middle latitudes, trees and shrubs flower and ripen fruit in the summer season. Seeds fall to the ground and remain in a dormant state until late the following spring when warmer temperatures trigger germination. Planting a tree from seed, therefore, should be done in spring once the danger of frost has passed. As insurance against failure, it is best to plant two or three seeds together in the same hole; if more than one germinates you can wait to see which is the healthiest and most vigorous and eliminate the others.
If the planting material is a seedling or even a sapling, spring in the middle latitudes is the best time to make the transplant. It should be remembered that young plants in their establishment phase are expanding their root systems in parallel with producing new branches and leaves. Hence young plants need to be protected from physical damage aboveground, with stakes or cages, and care taken not to impede full root development underground.
When planting tree seed in the subtropics or tropics, where temperature is not a constraint, it is recommended to sow seeds during the rainiest period, again with more than one seed per hole. Germination during the wetter season provides seedling plants with sufficient water and permits good establishment before the more active growing season of higher temperatures.
Transplanting a seedling or larger plant in warmer climates is best accomplished toward the end of the rainier season. This will allow the plant to become established and achieve good growth during the following warmer period. The comments above about transplanting in the middle latitudes also apply here.
Landscapers are not in agreement with regard to the practice of staking young newly-planted trees. Staking may discourage normal root development and physically damage the trunk, and is probably not necessary where soils are fertile. But staking for a year or two may be justified if soils are shallow or infertile. If stakes are used, care should be given to drive them into the ground so as not to penetrate the root ball.
Following these suggestions for the time of planting, along with recommended practices in terms of seedling selection, hole preparation, fertilizer application, watering and early pruning, should result in healthy and vigorous growth of the young tree.