It seems like all the plant nurseries have great big signs out now that say, “Fall is for Planting!” right next to their signs that say “50% Off Trees and Shrubs!”. Fall is for planting mums, ornamental cabbages and kales, and spring-flowering bulbs, but is it really a good idea to plant trees and shrubs in the fall? Who wants to be outside on a blustery fall day digging a planting hole while their fingers are turning blue? Couldn’t it wait until the spring?
Photo: Early fall planting give roots ample time to grow before the following summer.
The idea behind fall planting is that trees and shrubs will get a head start on root growth before hot, dry weather comes the following summer. With a larger root system, they will be better equipped to mine the soil for water than trees planted only a few months ago in the spring. Long Island summers certainly have their fair share of droughts and heat waves, and lack of water is the most common cause of transplant failure, so this is a valid concern. Yet some research has shown that fall planting is worse than spring planting or makes no difference. So what are we to do?
Provided you give your new plants enough water, you should be fine planting in the early fall, in September or October of a typical year. But in late fall, in November or December when there may have already been a couple frosts, you should be careful planting the following plants:
· Evergreens (especially broadleaf ones such as rhododendron or andromeda)
· Balled and burlapped trees with a coarse root system
· Extremely large trees (think 30 feet tall!)
The key to successfully transplanting evergreens in late fall is to make sure that they do not dry out over the winter. Typically winter soil is wet because trees are dormant and aren’t using water. But if a relatively warm day with bright sunshine and high winds comes along, the temperature of the leaf surface of evergreens can increase enough to cause transpiration and water loss. If the soil is still frozen or even at a cold temperature that restricts water movement into the roots, the plant can suffer from winter drought-stress known as winter desiccation. Evergreen leaves will turn brown and crinkle and may drop.
If you want to test your luck and plant evergreens in the late fall anyway, make sure to:
· Irrigate during a relatively warm winter day, especially when there has been no precipitation for a while and it will get cold again the next day.
· Apply a 2-3 inch layer of mulch to insulate the soil and keep it moist.
· Situate the plants in a non-windy location in partial or full shade (as long as they don’t require full sun) so that their leaves do not heat up as much in bright sun on a warm winter day.
· Consider applying an anti-desiccant at the beginning of the winter and following up with repeat applications.
You should also be cautious of planting balled and burlapped trees with a coarse root system or extremely large trees in the late fall. Some tree, such as oaks, naturally tend to have a coarser root system than others. Very large trees will also tend to have a coarser root system. This means that relatively few roots remain within the harvested root ball - the tree is more susceptible to drying out, and it has a smaller stored food supply which it needs to grow new roots and leaves in the spring. (Trees store a lot of the carbohydrates they make during photosynthesis in their roots over the winter.)
Photo: 25 foot tall Littleleaf Linden trees were successfully transplanted in early spring in Southampton.
If you are still thinking about planting a coarse-rooted species or very large tree in the late fall, consider:
· Planting a smaller-sized tree.
· Planting a container-grown tree.
· Planting a balled and burlapped tree that has been root-pruned to have a more fibrous root system during production.
So is fall for really for planting? The answer is the most common answer in horticulture – it depends. Know which trees and shrubs are risky to plant in the late fall, and think twice before you fall for some great end-of-season sales at the nursery.
