Many home gardeners wait until spring to transplant in their landscapes. But if perennial plants such as trees and shrubs could talk, they would tell you that August and September are the best times for transplanting.
In the Garden this Week
Skip the Wound Dressing After Pruning
It was once customary to apply an asphalt-based wound dressing to pruned surfaces. Extensive research conducted by Dr. Alex Shigo has conclusively demonstrated that wound dressing actually does a tree more harm than good by preventing callus tissue formation over the wound. Better to leave the wound alone to heal naturally. To promote rapid healing, wrap the wound with black plastic and secure with thumbtacks. The black plastic will block the sunlight and help in maintaining a high level of humidity, which promotes rapid formation of callus tissues.
The physiology of plant growth begs you to transplant in late summer and early fall.
Now is when the top growth of woody plants in our region begins to slow in preparation for winter. Instead of going into new vegetative growth for next year, nutrients and water turn to growing roots. Most woody plants, you see, do not grow roots at the same time that they grow shoots. In the spring, woody plants produce shoot growth. Then, while new shoots mature, they grow new roots. So when woody plants are putting out a flush of shoots, they are not producing roots. This process continues as daylight hours increase until June 21.
After June 21, daylight hours begin to shorten. When daylight hours equal night hours, shoot growth almost ceases, and root growth begins to increase.
Thus by transplanting woody plants in late summer, you take advantage of their natural growth cycles. When you transplant a tree or shrub, you want it to establish roots in the new soil as quickly as possible to better survive. Since the top of the tree or shrub has stopped growing, nearly all energy produced from photosynthesis is sent to the roots.
Because the new growth has matured, it will be less subject to wilting, which means that you will need to irrigate less often.
Nearly all herbaceous perennials such as daylilies and hostas also fare better when transplanted soon after flowering.
Another advantage to transplanting in August and September is that you will not sacrifice flowering. This is especially true with azaleas, andromeda, mountain laurel and rhododendrons.