Dogwood trees are prized for their spring flowering bracts, elegant form and, in some cultivars, decorative colored bark. They often show stress due to their shallow root system and thin, delicate bark. The shallow, spreading roots make the tree vulnerable to even slight, temporary drought conditions, alkaline soil, warm ground temperatures, overuse of fertilizers and root disruption. To rescue a dogwood, start by evaluating and correcting these common problems.
Feel the soil for moisture. Dogwoods need moist, well-drained soil, cannot tolerate drought and quickly wilt when they're in need of water. If the soil feels dry to the touch at just 1 inch down, water it immediately. Apply water all around the area under the tree canopy, starting a foot out from the trunk. Drench the soil to a depth of at least 10 inches, but do not make it sopping wet. Alternate shallow and deep watering every seven to 10 days. In warm weather, dry climates or when the tree is growing in full sun all day, more frequent shallow watering may be needed.
Fertilize the tree with a complete, slow-release or organic fertilizer designed for acid-loving plants. Fertilizer products designed for dogwoods, azaleas and rhododendrons are ideal. The slow-release or organic formulations are gentle on the roots. Don't use fast-acting chemical fertilizers, which can burn the roots and add to the stress the tree is already experiencing. Apply according to the product label dosing directions, and water it in well.
Boost the nutritional content of poor-quality ground soil by laying down a few inches of bagged compost, well-aged livestock manure or a combination of the two as topdressing. Spread it under the canopy of the tree starting a foot out from the trunk and extending to the drip line of the tree. Do not till the amendments into the soil; just lay them down on the surface to prevent disruption of the shallow roots.
Mulch around the base of the tree, over the fertilizer and soil amendments, with an organic material such as shredded bark, cocoa bean hulls or leaf mold. Much will hold moisture in the soil, insulate roots from warm temperatures or temperature fluctuations, and keep any competitive weeds at bay.
Inspect the tree for signs of disease or insect damage. Look for discolored, misshapen, punctured or spotted foliage. Identify if there are any weak or dead branches, perforations in the bark or trunk wood, or wounds and cankers on the limbs. Bag a sample of any of these that you find, and consult a nursery for a diagnosis and recommended treatment.
Conduct a soil test to determine if a specific trace nutrient is lacking, if there is a chemical imbalance, toxicity or disease in the soil, or if there is some fundamental incompatibility between the tree and the site.