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Consumer Horticulture

Department of Horticulture and Landscape Architecture

Yard and Garden News


Why Plants Fail to Bloom

By B. Rosie Lerner, Extension Consumer Horticulture Specialist

Flowering plants that don't bloom as promised can be a big disappointment in your garden. Reasons for lack of blooming are as diverse as the palette of plants from which to choose, but a little detective work can usually pinpoint the trouble. The most common factors associated with blooming are light, plant age, nutrition, winter temperatures and improper pruning.

Flowering may be sparse or completely absent when a plant is under stress, so be sure the plant is positioned in an appropriate location for that particular species. For example, some plants flower best in full sun; others may prefer the cooler conditions found in the shade. Some plants, such as peonies, will flower sparsely or not at all when grown in shade. Similarly, shade-loving plants, such as begonias, will not bloom well in full sun.

Some plants, such as chrysanthemums and poinsettias, flower in response to short day lengths, or more accurately, long nights. If the plants don't receive the appropriate break from light, their season of bloom will be delayed indefinitely.

Many woody plants must reach a certain age before they are mature enough to produce flowers. Fruit trees, such as apples and pears, can require as many as five or six years to become fruitful. Gingko trees can take up to 15 years to bloom. Add a stressful environment to a juvenile plant, and flowering may be delayed even further.

Overfeeding plants with nitrogen can encourage them to produce lush foliage at the expense of blossoms. A lack of nutrients, particularly nitrogen, phosphorus and potassium, also may delay flowering. Stick with a balanced, low-analysis fertilizer, such as 12-12-12 or 6-10-4, to apply adequate nutrition without overdoing.

Some gardeners unknowingly remove flower potential from their plants by pruning at the wrong time of year. Landscape plants that bloom in early spring set their flower buds in autumn on last year's growth. If you prune these plants in late winter, you'll also be removing many or all of the flower buds. The rule of thumb is to prune spring-flowering shrubs and vines after blooms have faded.

Mother Nature can deal a blow to buds with extreme low winter temperatures or late frosts in spring after growth has begun. Read up on your plants to know the best pruning time, and choose plants that are adapted to your area.


Last updated: 10 April 2006
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