"There are over 150 species" of viburnum shrubs, writes Marie Iannotti, About's Gardening Guide. "You can find a variety to suit any garden need: wet or dry, sun or shade, natural or formal, shrub or tree, native or exotic, USDA Zones 2-9. Bloom times span early spring through June and are followed by attractive fruit and outstanding fall foliage." It's no wonder then that viburnum shrubs are one of the most popular of the flowering bushes.