Dogwoods are not heavy feeders. A flowering dogwood in moist, acidic soil rich in organic matter, under a wide ring of mulch, often grows and blooms well without much fertilizer at all. When it does need a boost, a light spring feeding with the right kind of product does more good than a big dose, and feeding at the wrong time, especially during a summer drought, can do harm.

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The short answer: fertilize a dogwood lightly in spring, after the danger of frost has passed, with a balanced, slow-release, acid-forming fertilizer of the kind sold for azaleas. Clemson Extension says a second light feeding about six weeks later can encourage extra flowers or faster growth on young trees. Do not fertilize a drought-stressed tree in summer, do not fertilize at planting, and get a soil test if you are unsure the tree needs it.

Does your dogwood need fertilizer?

Start with the growing conditions, because most dogwood problems are not nutritional. Clemson Extension says dogwoods prefer moist, well-drained, acidic soil, pH 5.5 to 6.0, that is high in organic matter. The Morton Arboretum notes that flowering dogwood has a shallow root system, is sensitive to drought and develops problems in heavy clay.

The Morton Arboretum also cautions that fertilizer only fixes nutrient deficiencies. Lack of water, girdling roots and trunk damage can cause similar symptoms, so rule those out first. Its general advice is to add nutrients only if a soil or foliage test shows a deficiency.

Some signs worth testing for:

Pale green or yellow leaves. The Morton Arboretum notes that flowering dogwood becomes chlorotic, with pale green leaves, in high-pH soils. That points to soil pH rather than a lack of fertilizer, and a soil test will show what to correct.
Weak growth and small leaves on a tree that is getting enough water.

If your dogwood is not flowering, fertilizer is rarely the fix. See why a dogwood tree is not blooming for the usual causes, including pruning at the wrong time and too much nitrogen.

When to fertilize a dogwood

Clemson Extension recommends fertilizing dogwoods lightly in spring once frost has passed, and again about six weeks later if you want extra flowers or faster growth on a young tree. It specifically warns against fertilizing trees stressed by drought during the summer months.

The Morton Arboretum’s general guidance for trees is to fertilize no more than once a year, either in spring as new growth begins or in late fall once the tree is dormant, and to avoid late summer, when feeding can push new growth that will not harden off before winter.

Both sources agree on the main points: spring is a good time, feed lightly, and skip the stressful heat of late summer.

What kind of fertilizer to use

Clemson recommends a well-balanced, extended-release, acid-forming azalea fertilizer. By well-balanced, it means major nutrients in roughly a 2-1-1 ratio of nitrogen, phosphorus and potassium. Its examples include several azalea, camellia and rhododendron foods with analyses such as 10-6-8 and 10-5-4.

The Morton Arboretum adds that flowering trees can benefit from a fertilizer with slightly more phosphorus, such as 5-10-5 or 6-12-6, and warns never to use fertilizers that contain herbicides, such as weed-and-feed lawn products, around trees.

Which to choose? On naturally acidic soil, a slow-release azalea fertilizer suits a dogwood well. On alkaline soil, a soil test will tell you whether pH or a specific nutrient is the real problem.

How to apply it

Read the label and use the rate for trees and shrubs. Light is the key word with dogwoods.
Spread it evenly over the soil surface across the root zone, which extends beyond the branch tips. Do not pile it against the trunk.
Water it in if the soil is dry. Never fertilize a dry, wilting tree; water it first.
Keep the mulch. Clemson recommends a 2- to 3-inch-deep mulch ring at least 8 to 10 feet across around a mature tree, kept off the trunk. NC State suggests 2 to 4 inches to keep roots cool and moist. Mulch protects the shallow roots and adds organic matter as it breaks down.

New dogwoods: water, not fertilizer

The Morton Arboretum says fertilizing at planting is generally not recommended, because it is ineffective until the roots re-establish. It advises waiting two or three years, then testing the soil before fertilizing. For a new dogwood, consistent watering and mulch are what help it settle in. Clemson notes that container-grown dogwoods establish more quickly than balled-and-burlapped trees, and that fall is the best time to plant.

Common mistakes

Feeding a stressed tree. Fertilizer will not revive a dogwood suffering from drought, root damage or disease. See how to revive a dogwood tree.
Using weed-and-feed. The Morton Arboretum warns against using fertilizers that contain herbicides, such as lawn products, around trees.
Overdoing it. The Morton Arboretum notes that too much nitrogen at once can damage roots and push soft growth that is more prone to fungal disease.

For pruning timing that protects next year’s flowers, see how and when to prune a dogwood.

Sources

Dogwood, Clemson Cooperative Extension Home & Garden Information Center
How and When to Use Fertilizer on Plants, The Morton Arboretum
Caring for New Transplants, The Morton Arboretum
Flowering Dogwood, The Morton Arboretum
Cornus florida (Flowering Dogwood), NC State Extension Gardener Plant Toolbox
Garden Calendar, The Morton Arboretum

Top photo: Agnieszka Kwiecień, Nova, CC BY-SA 4.0, via Wikimedia Commons

How and When to Fertilize Dogwood Trees