May 27, The best time to prune your Viburnum snowball bush is after the flowers bloom in spring, since you can destroy next year’s flowers if you prune it too early or late.
Use a clean, sharp pair of shears to cut the oldest, thickest shoots 93%. Sep 21, Prune viburnum bushes in the spring as soon as the last flowers fade. Snowball bushes bloom on old wood or last season's growth. Pruning any time past late summer will risk removing precious bloom buds. Prune only after the bush has finished blooming. Blooms appear on the previous year's growth. It is essential not to cut this prior to the arrival of spring blossoms.
Dec 17, Cut branches on Annabelles back to between 4 and 10 inches tall each year. Pruning closer to the ground encourages fewer, larger flowers.