Mountain laurel (Kalmia latifolia) is a spectacular native evergreen shrub that blooms in late spring or early summer. Pruning can make or break a bloom season; knowing when to prune is an important part of routine maintenance for this shrub. All parts of the plant are poisonous; keep this in mind, both when choosing to include this shrub in your landscape and when disposing of the cuttings.
When you first plant a new flowering shrub, you want to see it bloom as soon as possible. Sometimes, however, you need to prune young shrubs to help shape their long-term growth. North Carolina Cooperative Extension's John Vining cautions that if you prune mountain laurel to shape the shrub, you must do it before spring bud break. However, this removes the upcoming season's blooms. Some cultivars may particularly benefit from pruning as young shrubs. For example, K. latifolia "Elf" tends to get leggy if it isn't pruned, according to the University of Connecticut.
Although pruning can sometimes mean a loss of one season's blooms, pruning under other circumstances is a way to encourage better flowering. Mountain laurels are one flower-truss-forming shrub that many experts recommend deadheading -- pruning off the spent flowers to encourage the next season's blossoms. Preventing seed formation may conserve the shrubs' resources for the next year's flowering shoots. It is important to break off the old blooms soon after they shrivel to prevent damage to the new growth underneath.
Shrub rejuvenation is the most drastic form of pruning. If you want to keep your mountain laurels shorter or fuller, cutting back older shrubs to 2-foot or shorter trunks produces new growth and restores overgrown plants. After regrowth begins, thin and cut back again when the new growth is 6 to 12 inches long, advises North Carolina horticulturalist Erv Evans.
Mountain laurels typically grow slowly enough that they don't require much pruning, according to Delaware Cooperative Extension's Jay Windsor. It is best to remove dead, diseased or otherwise damaged or unwanted branches as soon as you notice them, however. Always prune back into healthy wood to assure the best recovery for your mountain laurels.