Viburnum bushes grow well without an intensive fertilizer regimen. These plants prosper in average garden soils where other landscape plants remain healthy. Conduct a soil test to learn about your soil's pH and nutrient levels before relying on fertilizers.
Any well-balanced, slow-release fertilizer works well for viburnum shrubs. A 10-10-10 formulation with micronutrients makes an excellent choice, as it benefits other plants in the landscape, too.
The ideal time to scatter fertilizer around viburnum shrubs is late winter before the new growth begins. This lets the granules decompose and leach into the topsoil to be among the plant roots as the plant develops leaves. If you want lots of fruits, apply a secondary, half-dose of fertilizer after the spring flowering.
Garden soils enriched with organic matter like compost and well-rotted manures and top-dressed with a 3-inch layer of leaf or bark mulch annually produce a nutrient-rich growing environment. This approach to garden management makes fertilizer applications to viburnums unnecessary.