Viburnums do not usually need watering except when they're first planted, in time of drought, or in late fall before the ground freezes for the winter. If you do water, give your plants 1 gallon of water twice a week or run your drip irrigation system or sprinkler for 20 to 30 minutes twice a week. Older shrubs need watering only during severe drought.
For more information see file on About Watering Equipment.
These shrubs need only one yearly application of bagged sludge, a granular fertilizer with a slow release form of nitrogen, or compost. In the fall, spread a 10-10-10 fertilizer on the soil to 1-1/2 feet beyond the tips of the branches (drip line). You may wish to supplement the fall feeding with 2 or 3 monthly snacks in late spring and early summer. Use a light side dressing of granular fertilizer or apply a foliar spray of dilute liquid fertilizer over all the leaves of the plant.
For more information see file About Fertilizers.
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Viburnums do best when they have a 2- to 4-inch layer of organic mulch over their root zone all season long. Keep the mulch about 6 inches away from the trunk to avoid decay and rodent damage. Use chopped leaves, pine needles or wood chips to mulch viburnum. Avoid mulching with un-chopped leaves because they mat together, preventing water from getting into the soil. Peat moss makes poor mulch, because it draws water from the soil like a wick and is difficult to rewet when dry.
For more information see file on Using Mulch.
Healthy specimens rarely need pruning. Prune Viburnums after flowering only if pruning is necessary for shaping. Old or crowded plants may be thinned and shortened to bring flowers to eye level. After 4 to 5 years you may remove 1/3 of the oldest stems, and thereafter prune every 2 or 3 years. For a more formal effect, it is possible to train Viburnums to a single trunk. Choose the healthiest and most upright stem when young and keep side shoots pinched until it reaches the height you want. Then allow the plant to branch from the top.
For more information see files on Pruning Shrubs and Choosing Pruning Tools