Buds may die or drop for any of several reasons.
1. Transplant shock: Whenever a tree or shrub is transplanted, it goes through a period of shock. Dormant plants usually recover more quickly and are injured less than growing plants. However, even when transplanted properly, dormant plants may still lose some of their buds. Plants that have begun growth or are in bloom often drop many of their flower buds or flowers shortly after transplanting. Some buds may remain on the plant but not open.
2. Cold or frost injury: Flower buds or flowers may be killed by cold or freezing temperatures. Many or all of them either fail to open or drop off. Cold injury occurs during the winter when temperatures drop below the lowest point that can be tolerated by buds of that particular plant species. Frost injury is caused by an unseasonal cold snap, in either fall or spring, which damages buds, developing flowers, and tender shoots of growing plants.
3. Drought: Flowers or flower buds dry and drop off when there is a temporary lack of moisture in the plant. This may be due to dry soil, minor root injuries, or anything else that disrupts water movement to the top of the plant.
4. Insects: Certain insects, such as thrips and mites, feed on flower buds. When infestations are heavy, their feeding kills flower buds, causing them to dry and drop off. Some infested buds may open, but are distorted.
The numbered solutions below correspond to the numbers in the analysis.
1. Whenever possible, transplant trees and shrubs during the dormant season. (For more information about transplanting, see Planting and Transplanting.) Avoid wounding the roots when planting, and do not let the plant dry out. (For more information about watering, see About Watering.) Apply an antidesiccant spray to plant a few days before transplanting.
2. Plant trees and shrubs adapted to your area. Consult your local garden center, County Extension Agent (see County Extension Agents), or a book on plant selection, such as ORTHO's books Shrubs & Hedges or All About Trees. Protect shrubs and small trees from early or late cold snaps by covering them with burlap or a plastic tent. Placing a light underneath the covering will offer additional protection.
3. Water trees and shrubs regularly. (For more information about watering, see About Watering.) Most plants will recover from minor root injuries. Frequent shallow waterings and light fertilization (see Nitrogen, Phosphorus) may speed the recovery process. Avoid wounding plants.
4. Insects can be controlled with various chemicals. For more information about thrips and mites and their controls, look under your specific plant or in Thrips.
