Care for Plants Breaking Dormancy Early

This winter has been unseasonably warm for many areas of the country; so warm, in fact, that many flowering plants are being tricked into showing their true colors long before spring.

But if your customers are worried about seeing premature buds on their trees and shrubs, they need not worry. The Kansas State University Research & Extension office says that while there may be little you can do to slow bud development, early blooming is not likely to damage plants.

KSU explains that plants that go dormant in winter must have a certain number of “chilling hours” before buds will begin growth the following spring. Chilling hours are those in which the temperature remains between 32 and 45 degrees F. Plants differ in the number of chilling hours needed, with those adapted to colder climates usually requiring more than those adapted to warmer zones. Even plants within the same species can differ markedly in the number of chilling hours required for bud break. For example, apple varieties range from a low of 250 (or fewer) chilling hours to a high of 1,700.
 
The chilling requirements of some plants have been met already this winter. For these plants, dormancy is over and warm periods can lead to bud swell. Unfortunately, buds that have swollen have lost virtually all of their winter hardiness and can be damaged by severe cold.
 
So what do you do if you have a plant that has swollen buds? Not much, because the process is completely dependent on weather. However, watering during dry weather may help in an indirect way. Roots can suffer drought damage during the winter. A tree with a damaged root system and damaged buds will be slower to recover than one with just damaged buds. Readily available soil moisture will aid in keeping the plant healthy so it will be better able to recover from cold damage. Also, it is important to determine if the swollen buds are flower buds or leaf buds. Even if the flower buds are killed by cold temperatures, the health of the plant should not be affected. If, in addition to the swollen buds, you also see small buds on the stems, then the swollen buds are flower buds and the small buds are leaf buds.
 
Even if the leaf buds swell and are killed by a cold snap, a healthy tree will still be able to survive. There are secondary buds that remain dormant unless the primary bud is killed. Secondary bud growth may be slower and less vigorous, but the tree will eventually recover.