Summer snowflake viburnum, known botanically as Viburnum plicatum tomentosum, is a species of flowering shrub belonging to the honeysuckle family of plants. It is a relatively new varietal introduced by the University of British Columbia Botanic Garden. Summer snowflake viburnum produces double rows of crisp white flower bunches along the shrub branch in a horizontal growth habit. It grows up to 15-feet in height at maturity. While botanically considered a shrub, it can also be pruned to resemble a small tree. It blooms from mid-spring through into mid-summer with bronze red foliage in the fall and winter. Viburnum sets its buds for the following year's bloom very early, so any significant pruning should be done immediately following the blooming period. Any later risks removing the following year's flower-producing wood.
Prune damaged or diseased branches and spent flowers that are spotted on the summer snowflake viburnum while watering throughout the year. Make any cuts, using the pruning shears, at least one-quarter inch beyond an outward facing leaf node or bud on the branch. This encourages branching and increases the fullness of the shrub.
Cut viburnum branches for use in cut flower arrangements as blooms reach their peak. Pick the spot to cut using the same guideline mentioned in Step 1. Cut up through the stem, vertically, to encourage water uptake. Place the branch in a vase of cool water, store in a cool location out of direct sunlight and replace the water each day.
Prune viburnum for shape and size once a year--or less frequently. Locate cuts one-quarter inch beyond an outward facing leaf node or bud to encourage outward facing branching and fullness. When pruning for shape and height, remove no more than one-third of the branching and foliage in any one session.
Prune to improve sunlight penetration and airflow in the viburnum's interior by cutting branches that cross each other. Reduce the risk of disease by cutting back any branch that abrades another.
Prune to create a tree shape by removing at least several feet of the lower branches and foliage from the shrub. Prune any branching from the soil toward the canopy. This should leave a single clean trunk. If you wish, you can leave multiple trunks. When initially creating the tree shape remember to remove only one-third of the shrub volume at a time. If more of the shrub must be pruned to achieve your desired tree shape, remove it in successive pruning sessions.