Constellations of dogwood (Cornus spp.) blooms sparkling against freshly greening deciduous trees or dense, dark conifers presage winter’s end. Various dogwood trees thrive across U.S. Department of Agriculture plant hardiness zones 4 or 5 through 8 or 9. Prized for their compact stature, ornamental blooms and berries and often luminous fall color, dogwoods tolerate spring or autumn planting. Space them 20 feet apart, in full sun to partial shade. In hot-summer climates, they perform best in partial shade.
Several factors determine how much water an individual dogwood needs. During the first two years after planting, or when receiving less than 1 inch of weekly rainfall, trees need regular watering. Slowly soaking the top inch of soil with a sprinkler or drip irrigation is adequate. Dogwoods in moisture-retentive, organically rich soils require less water than those in sandy areas. Where the soil freezes in winter, supplemental fall watering prepares the trees for dormancy, but this isn't necessary in rainy-winter frost-free climates.
Dogwood trees' shallow roots reach well beyond their driplines, where rain falls to the ground from the outermost leaves. Spreading a 3-inch layer of pine bark or straw from well beyond the dripline to 6 inches from the trunk prevents moisture evaporation while stabilizing soil temperature. The mulch helps control weeds, but hand-pulling those that do sprout is less damaging to the shallow roots than using a cultivating fork.
A single tablespoon of granular, 16-4-8 general-purpose fertilizer in early spring and midsummer is adequate for recently planted, 1- to 2-foot dogwoods. Increase to 4 tablespoons scattered in a circle 2 feet from the trunk, for recently planted 6-foot trees. Replenishing the decaying organic mulch layer whenever it's reduced to 2 inches provides the soil with a constant source of nutrients, eliminating the need for fertilizing trees older than 3 years.
Anthracnose devastates many flowering dogwood cultivars as well as "Chinese" and Pacific dogwood trees (C. florida, C. kousa "Chinensis," C. nuttalli). Spotted new shoots with cankered stems signal its presence, while severe anthracnose causes early leaf drop and may completely defoliate a tree. Raking up infected debris during the growing season and pruning diseased branches during winter dormancy help halt its spread. Resistant dogwood cultivars include "Sunset" and Spring Grove" (C. florida "Sunset," C. Florida "Spring Grove").
Dogwoods frequently attract dogwood borers. These metallic blue, green or copper-hued beetles deposit eggs in the tree's bark crevices, where their larvae tunnel into the underlying tissue. Heavy borer activity causes branch dieback and may be fatal. Tree bark damaged from mowers or string trimmers invites a borer attack. Drought stress also increases a tree's risk.
Thanks to their naturally tidy habits, dogwood trees require minimal pruning. The times for light shaping and removing dead or damaged branches and root suckers are in winter or just after spring bloom.
- Fine Gardening: Genus Cornus
- National Gardening Association Plant Care Guides: Dogwood
- University of Missouri Extension: Tree Placement on Home Grounds
- University of California Integrated Pest Management Program: Dogwood
- Yardener: Caring for Dogwood
- University of Georgia College of Agricultural and Environmental Sciences: Growing Dogwood
- University of California Integrated Pest Management Program: Canker Diseases
- University of California Integrated Pest Management Program: Flatheaded Borers
- University of California Integrated Pest Management Program: Anthracnose
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