Few trees announce spring like a dogwood in full bloom, so a dogwood that leafs out with no flowers is a real disappointment. The good news is that the cause is usually environmental or cultural, and fixable. The University of Maryland Extension lists the main reasons trees fail to flower: immaturity, environmental stress, too much lush growth, improper pruning, winter kill and pesticides.
The short answer: the most common reasons a dogwood doesn’t bloom are that it is still too young, it lost its flower buds to a late frost or harsh winter, it was pruned in mid to late summer after the buds formed, it is in too much shade or hot sun, it was stressed by drought the previous summer, or it got too much nitrogen fertilizer. Most of these resolve in a season or two with the right care.
How dogwood flowers form
Dogwoods set their flower buds in summer for the following spring. The Morton Arboretum notes flowering dogwood flowers on old wood, so the buds have to survive late summer, fall and winter on the branch. You can usually spot them in fall and winter: flower buds are round and onion-shaped at the branch tips, while leaf buds are narrow and pointed.
Check your tree in winter. If you see plenty of round buds, it should bloom unless frost gets them. If there are none, the problem happened the summer before.
Cause 1: the tree is too young
The University of Maryland notes that most flowering trees must be physiologically mature before they bloom. Dogwoods grown from seed or from suckers can take many years. A young nursery tree may also take a year or two after planting to settle in before flowering well.
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Cause 2: frost and winter damage
Late frost is, in the University of Maryland’s words, a very common reason for failure to bloom. Flower buds that have started to swell are easily killed by a hard frost. The Morton Arboretum notes flowering dogwood is borderline hardy in the Chicago area and harsh winters can damage its flower buds. Kousa dogwood is hardier and blooms later, so it is often more reliable in cold areas.
Cause 3: pruning at the wrong time
Because buds form in summer, pruning in mid to late summer or fall removes next year’s flowers. The University of Maryland advises that most spring-flowering trees be pruned by the end of June, and its dogwood guide suggests pruning right after flowering or in late fall to early winter. Pruning more than a third of a plant at once also triggers leafy growth instead of flowers. See how and when to prune a dogwood.
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Cause 4: the wrong amount of light
Flowering dogwood is a forest understory tree. The University of Maryland says it grows best in partial shade and is not tolerant of full sun or hot, dry conditions. In deep shade, though, it will flower poorly. A spot with morning sun and afternoon shade, or the dappled light under tall trees, is ideal. Kousa dogwood tolerates more sun.
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Cause 5: drought the previous summer
Drought while buds are forming in summer reduces flowering the next spring. Dogwoods are shallow-rooted and compete poorly with lawn grass; the University of Maryland notes they may need watering in July and August. Check the soil 4 to 6 inches down with a trowel and water when it is dry at that depth.
Cause 6: too much nitrogen
Lawn fertilizer spread near the tree pushes lush, leafy growth at the expense of flower buds. The University of Maryland recommends fertilizing dogwoods only according to a soil test, not routinely. An annual topdressing of compost is enough for most trees.
Cause 7: stress, pests and diseases
Diseases such as dogwood anthracnose and powdery mildew, borer damage and root problems all weaken a tree and reduce flowering. If your dogwood also has spotted leaves, dying branches or holes in the bark, see why a dogwood tree is dying.
Quick diagnosis
| What you notice | Likely cause |
|---|---|
| Young tree, planted in the last few years | Not mature yet |
| Buds were present in winter but no flowers | Late frost or winter kill |
| No round flower buds in winter | Summer pruning, drought or too much shade last year |
| Very leafy, long new shoots | Excess nitrogen or heavy pruning |
| Scorched leaves in summer, few flowers | Too much hot sun and drought |
Some trees also flower heavily one year and lightly the next. The University of Maryland notes that some species have alternate flowering patterns.
What to do this year
- Mulch a wide ring, up to 3 inches deep, keeping it off the trunk, and remove grass from the root zone.
- Water deeply during dry spells, especially from midsummer on.
- Stop fertilizing unless a soil test shows a need.
- Prune only right after flowering, and lightly.
- Check for flower buds in winter to see whether next spring looks promising.
Sources
- Trees and Shrubs Failing to Flower, University of Maryland Extension
- Growing Flowering Dogwood Trees, University of Maryland Extension
- Flowering Dogwood, The Morton Arboretum
- Kousa Dogwood, The Morton Arboretum
- Dogwood, Clemson Cooperative Extension HGIC
Top photo: Famartin, CC BY-SA 4.0, via Wikimedia Commons