Flowering Dogwood

Site and soil

Flowering dogwood is an understory tree and it behaves like one. The spec sheet lists it for full sun and it will take full sun, but the USDA NRCS plant guide says partial or broken shade suits it best, with more sun tolerated in the north and some shade wanted in the south. NRCS also describes the trade: trees in more sun are stouter and bushier and carry more flowers, while shaded trees grow taller and thinner and flower poorly. Clemson Extension adds one siting rule worth keeping, which is to pick a spot with good air circulation.

Soil

Coarse to medium textured, well drained soil, in the pH band on the spec sheet of 4.8 to 7.7. NRCS reports best growth in coarse to medium textured, well drained soils with a pH of 6 to 7, and Clemson describes the ideal as moist, fertile, sandy or loamy, slightly acidic and well drained. What dogwood will not take is heavy saturated ground. NRCS notes trees can be uprooted in waterlogged soil and that excess water leaves the plant open to pests and disease, and it credits the shallow root system for the tree's poor showing on very dry sites too. Middle ground, well drained and never baked.

Size and spacing

Plan for a tree up to 30 ft tall with a crown 15 to 30 feet wide, the figures NC State Extension gives, on the horizontal branches NRCS describes as spreading wider than the tree is high. Clemson calls it a slow to moderate grower, roughly 15 feet in 18 years, and faster in shade. The 4 to 6 foot spacing on the spec sheet is close planting, the kind you use for a thicket or a woodland edge where the crowns are meant to knit together. If you want each tree to carry a full rounded crown, give it 15 to 20 feet of room and work from the mature spread instead.

Planting

Plant them dormant, in late fall or in early spring before the buds move. Clemson Extension says fall is the best time to plant a dogwood. The steps below follow WVU Extension's guide to planting a bare-root tree seedling.

• Soak the roots in water for one to six hours before planting. WVU warns that longer will drown them.
• Dig a hole wider than it is deep with sloped sides, only deep enough that the taproot is not bent.
• Set the tree so the root flare is level with the original soil line.
• Gently spread the roots so none are turned or bent, and prune out any that are damaged or strongly curved.
• Backfill with the soil you took out and tamp it down very gently.
• Water with several gallons right away to set the tree in place.
• Mulch 2 to 3 inches deep and keep it off the trunk. NC State recommends a 2 to 4 inch layer to hold the roots cool and moist, and NRCS notes dogwood is sensitive to rapidly changing soil temperature, which is exactly what a mulch ring buffers. WVU adds that mulch also keeps string trimmers away from the bark.

One honest note about bare-root dogwood. NRCS says flowering dogwood can be difficult to transplant, and that seedlings moved with a root ball establish more readily than bare-root stock. That is not a reason to avoid bare root, it is a reason to be quick and careful with it. Keep the roots moist and shaded from the moment the box is open until the hole is filled, and do not let them dry out on the tailgate while you dig.

First-year care

Water is the whole job in the first year. NRCS is specific about it: flowering dogwood is intolerant of extended drought, especially in the first year after planting, and daily watering is necessary for the first few weeks after planting. After one month, drop back to twice a week and hold that for a year. The spec sheet lists this tree as low water, and that is true of an established dogwood in shade. It is not true of a first-year transplant.

Clemson adds deep irrigation during dry spells and calls it essential through the first few years of establishment, most of all for trees in the sun. Longer term, NRCS splits it cleanly: established trees in partial or deep shade need water only in a drought, while trees in full sun will want irrigation throughout their lives.

Protect the trunk

Dogwood borer larvae get in through openings in the bark, and NRCS names mower and string trimmer wounds as the entrance we hand them. Keep machinery away from the trunk, keep a mulch ring where grass would otherwise need cutting, and do not wound the bark. The same habit prevents canker, which NRCS says forms at wound sites and cannot be controlled once it takes hold.

Fertilizer

Go light. Clemson suggests a light spring feeding once frost has passed, with a balanced, extended release, acid-forming azalea fertilizer, and a second feeding six weeks later. NRCS advises avoiding nitrogen fertilizer where dogwood anthracnose is a concern. If you are in anthracnose country, see below, feed sparingly or not at all.

Pruning

Keep pruning to a minimum and do it after flowering in early summer, which is Clemson Extension's guidance for this species. Then prune for health rather than shape.

• Dead, damaged or crossing wood, whenever you find it.
• Twigs with wilted tips at the ends of branches. NRCS says twig borers tunnel through the pith and can be handled by pruning the affected twig below the discolored pith.
• Swollen galls at the base of the leaves, the work of the dogwood club gall midge. NRCS says the galls can be pruned out and destroyed, and that a light infestation does no real harm.
• Crowding vegetation around the tree, plus a light thinning of the interior canopy, to move air through it.

Anthracnose

Dogwood anthracnose is the disease that matters for this species. NC State Extension notes it is not all that common and occurs mainly at 1,800 feet of elevation and higher, which covers a fair share of the Appalachian plateau, so it is worth knowing your own elevation. NRCS describes it as controllable if it is caught before branch dieback begins: prune and remove all dead twigs, dead limbs and new shoots, rake and remove fallen leaves, thin the canopy and clear crowding vegetation for air circulation, and avoid nitrogen fertilizer. Spot anthracnose is the milder relative, and clearing fallen leaves helps there too, since NRCS says that is where the fungus overwinters.

Harvest

Read this one before anyone grazes on the red berries. The USDA NRCS plant guide carries a plain warning that the fruit of flowering dogwood is poisonous to humans. This is a wildlife tree and a flowering tree, not a fruit crop, and nothing on it belongs in a kitchen basket.

What you do harvest is the show and the wildlife. NRCS says the flowers appear between March and June, with or before the leaves, and hold for two to four weeks, while NC State dates the bloom to March through May, before leaf-out. The fruit is a glossy red drupe about half an inch long that NRCS says ripens in September and October, and NC State lists the display from August into October. Fall foliage turns red to purple. NRCS lists the eaters: songbirds, forest edge birds and upland game birds such as wild turkey, plus eastern chipmunk, white-footed mouse, gray fox, gray squirrel, black bear, beaver, white-tailed deer and skunk.

If you want seed

The USDA Forest Service Woody Plant Seed Manual says to collect dogwood fruit when a squeeze pops the stone out, and to collect as soon as it is ripe so the birds do not take the crop first. The same manual gives the reason to plant more than one tree: fruit should not be collected from isolated flowering dogwoods, because they appear to be self-sterile and a high percentage of their stones will be empty. NRCS describes hand sowing fresh seed into an outdoor bed soon after collection in September or October, 5 to 6 inches apart in rows, mulched with sawdust, with the mulch pulled before spring emergence in March or April, and says plants are best suited for transplanting at the beginning of the third year.

Years to bloom

Expect patience, and expect it to depend on how the tree was propagated. The NC State Extension Master Gardener Volunteers of Buncombe County report that seed-grown dogwood seedlings typically take 7 to 10 years to bloom, while trees started from cuttings can flower in two or three. Clemson notes the same split, that seed-grown dogwoods vary in the age they begin flowering and that almost all dogwoods sold in the trade are asexually propagated and flower young. If the timeline matters to your planting plan, ask us which kind you are getting before you order.