Garden Topics: Fall...It's the Time to Transplant
Being dug from the ground and transplanted is stressful for plants whenever it occurs, but we can insure success if we do it during the proper season. A healthy, thriving plant needs a vigorous root system to feed and nourish its leaves and flowers. Fine, specialized feeder roots pull water out of the soil and feed it to the larger root parts. When a plant is dug from the ground, it is impossible to keep all of the fine feeder roots intact; plants becomes stressed when they can no longer take in enough water. Even though plants are incredibly resilient and can, in time, regenerate new feeder roots, they can also perish from drought stress. That period of uncertainty is referred to as "transplant shock."
One way to minimize the shock is to transplant at the right time. Consistently moist, well-drained soil, with the right balance of water and oxygen, is best for regenerating healthy roots. Spring and fall are seasons when more consistent rainfall and cooler temperatures prevail, generally making these seasons the best times to transplant. Fall transplanting should take place soon after leaf drop. This timing will providing time for new water absorbing roots to develop before the soil freezes.
Moving deciduous plants (those that loose their leaves in the fall) when they are dormant makes- for an even easier transplant because they adjust their top growth by growing fewer, smaller leaves in the following growing season.
There are, of course, exceptions. Some woody plants should be dug only in spring, like birches, oaks, and magnolias. Most evergreens can be transplanted in spring and again in midsummer through mid fall, when they are not involved in active growth.
Some perennials such as iris, hosta, poppies and daylilies should be transplanted late summer through fall.