The kousa dogwood (Cornus kousa) is a large shrub or small tree enjoyed for its bark, long-lasting flowers, form, fall coloring and edible red fruits. Sometimes, a kousa dogwood fails to bloom as expected. There are a number of causes for failure to boom.
Kousa dogwoods may not produce flowers for several years following germination and transplant. According to Janet Carson of the University of Arkansas Cooperative Extension, a dogwood may require up to 7 years before it is mature enough to produce blooms. This is true even if the dogwood previously produced blooms while growing in a container.
Too Much Nitrogen
Over-fertilization limits blooms. Excess nitrogen stimulates new herbaceous growth, while limiting flower production. Fertilizer application to turf surrounding the tree or to adjacent plants may affect the dogwood.
Environmental and Site Factors
A number of environmental and site factors influence whether a dogwood blooms. This plant blooms optimally when nights are considerably cooler than days. Too steady a temperature negatively affects the number of buds produced. Dogwoods planted in too much shade do not bloom. This plant prefers about half a day of sunlight with midday shade in warmer climates.
Time of Year
Kousa dogwoods bloom later in the season than other dogwood species. Do not assume that if a kousa is not blooming at the same time as flowering dogwood, it skips bloom entirely. The flowers, which are actually white-to-pink bracts, appear after leaves emerge in spring or early summer.
A number of factors negatively affecting kousa dogwood's health impact flowering indirectly. In this case, the dogwood also exhibits more indicative symptoms of these issues. Potential bloom-inhibitors include toxicity from chemicals, scale infestation, ice damage or powdery mildew. Improper pruning or pruning at the wrong time may prevent flowering. Do not prune kousa dogwoods in spring before bloom or in late fall when buds are set.
- University of Arkansas Cooperative Extension; Ask Janet Carson: Trees - Dogwood (page 1)
- University of Arkansas Cooperative Extension; Ask Janet Carson: Trees - Dogwood (page 2)
- North Dakota State University Cooperative Extension Service; Ron Smith
- University of Florida IFAS Extension; Cornus kousa: Kousa Dogwood; Edward F. Gilman, et al.; November 1993
- Clemson Cooperative Extension; Dogwood; Debbie Shaughnessy, et al.; February 2000
- Purdue University Extension; Flowering Dogwood Doesn't Flower; Beverly Shaw
- Photo Credit Jupiterimages/Photos.com/Getty Images
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