Keeping Boxwood Happy
Provide excellent drainage: Boxwood is highly adaptable to various soil types, including average or poor soils as well as acidic or alkaline provided the soil is well-drained. Boxwoods can’t take standing water and heavy, wet soil which can lead to root rot. Prevent by amending soil with lots of organic matter and planting high when installing.
Keep it clean: Prune back all dying branches to healthy wood, remove all debris from the center of the plant, and thin out some of the outside growth so that air and light can reach the center.
Exposure: Boxwoods thrive in full sun or light shade, but they don’t like exposed, very windy sites, particularly in winter. Protect by watering as needed in late fall and apply a fresh layer of mulch in fall to help prevent winter damage.
Fertilizing and watering: Apply a balanced, all-purpose fertilizer (10-10-10) in spring to encourage leafy growth and again in fall to promote root growth. Monthly application of compost tea and use of drip irrigation, which might mitigate blight..
Back from the brink: If you have a younger, smaller boxwood that’s not doing well, prune back the dead branches, open up the center of the plant, sprinkle one or two cups of a slow-release fertilizer around the shrub, and water it in. If your plant is older, one of the slower-growing varieties, or taller than 3 feet, the time to recover makes trying to save it impractical. Replace it with a new one.