When to Prune a Fothergilla
With their brilliant fall color and fragrant, bottlebrush flowers, fothergillas (Fothergilla spp.) make graceful additions to sunny or partially-shaded gardens. These native shrubs are useful as foundation plants, in shrub borders and when massed. Related to witch hazels, they combine well in home landscapes with azaleas and rhododendrons, as well as Japanese andromeda.
Large fothergilla (F. major) is native to the Allegheny Mountains of the eastern United States, while dwarf fothergilla (F. gardenii) grows naturally along the Southeastern coastal plain. Both shrubs are hardy to U.S. Department of Agriculture Zone 5 and are rarely troubled by insects or diseases. Large fothergilla grows 6 to 8 feet high and wide, while dwarf fothergilla stays at 3 to 6 feet. The shrubs are valued for their white, fragrant flowers and their outstanding fall color in shades of yellow, orange, red and purple.
Fothergillas bloom on the previous season's growth, so wait until flowering is finished before pruning. May, June and July are the best months for pruning, which is only necessary if you need to control the shrub's size. Pruning before the late-spring flowers emerge will ruin the flower display, and pruning after midsummer will remove the next season's flower buds.
Pruning Damaged or Diseased Stems
Damaged or diseased stems should be removed whenever found, regardless of season. Make a clean cut below the break or diseased area, being sure to sterilize your pruners between cuts with alcohol or a mixture of nine parts water to one part household bleach.
An Exception for Blue Varieties
Fothergillas naturally have bluish-green foliage, a trait that's been manipulated by plant breeders to produce cultivars such as Blue Mist with pronounced blue foliage. With blue-foliaged cultivars, as with variegated forms of other plants, be on the lookout for branches that revert to the original plant coloration. These rogue branches must be cut back entirely as soon as they're seen, since they're usually more vigorous than the altered form and will eventually overtake the shrub, much in the same way rose bushes revert to wild cultivars if root suckers aren't removed.