University of Maryland Extension

Trees and Shrubs - Failure to Flower

flowerless dogwood

Lack of blooms dogwood

excessively pruned azalea

Excessive pruning of an azalea

There are several possibilities as to why trees and shrubs may not produce flowers. Factors include maturity, environmental stresses, excessive lush growth, improper pruning, lack of pollinators, winter-kill and pesticides.

  • Most flowering trees and shrubs must be a certain age before they will reproduce.
  • Environmental stresses that may prevent flowering are drought, low light, excess water, winter-kill of flower buds and late frost damage.
  • Excessive lush growth results from an excess of nitrogen fertilizer, which promotes vegetative growth and fewer flowers.
  • Pruning: Improper timing of pruning spring flowering trees and shrubs will result in the removal of flower buds. Pruning at the wrong time can also result in uneven flowering if some, but not all, flower buds are removed.¬†Most spring flowering trees and shrubs set flower buds in late summer and should be pruned by the end of June. Lilacs should be pruned immediatley after flowering. Timely pruning will allow new growth to mature enough to form flower buds in late summer. Other improper pruning methods, such as excessive pruning can result in failure to flower. Pruning is considered excessive when more than one-third of a plant is removed at a time. This type of pruning stimulates vegetative growth and results in little or no flower bud formation.
  • Improper pesticide use can damage or kill flower buds.
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