How to Maintain a Boxwood Hedge

Spread 2 to 3 inches of mulch, such as wood chips, compost or dry grass clippings, around the base of the boxwood shrubs. A layer of mulch keeps the shrub's shallow roots cool and moist. Extend the mulch at least 12 inches beyond the tips of the outer branches.

Fertilize a boxwood hedge in spring or early summer, using a fertilizer formulated for evergreens. Follow the rate recommendations on the package, and don't overdo, because too much fertilizer may burn the boxwood roots. A deep watering immediately after fertilizing protects the roots from damage.

Water a newly planted hedge regularly, keeping the soil consistently moist to a depth of 6 to 8 inches, so the roots don't become dry. Use a drip system or allow a hose to drip slowly at the base of the shrubs. An established boxwood hedge is relatively drought tolerant but benefits from a deep watering during spring and summer when rainfall is less than 1 inch per week.

Irrigate a boxwood hedge deeply in late autumn, because moist soil keeps the roots healthy and protects them from damage caused by freezing and thawing. Late autumn watering is especially critical in cold climates, because frozen soil is unable to absorb water.

Thin a boxwood hedge every year to allow water and sunlight to reach the center of the plant. Use pruning shears to remove the oldest stems by cutting them at ground level, or at the point where the stem grows from a larger stem. Remove low-growing branches and broken or damaged branches. Thinning is safely done any time of year, except during freezing weather.

Prune a boxwood hedge in early summer to maintain the desired size and shape. A hedge pruned to a natural, slightly rounded shape with the top slightly narrower than the bottom is healthier, because all parts of the shrub have access to sunlight. In addition, a rounded top sheds snow. Avoid pruning in late summer or autumn, because pruning encourages tender new growth, which is susceptible to damage from winter cold.

Use a broom or stick to remove heavy winter snowfall from the top of the boxwood hedge. Snow may be heavy enough to break the branches.