The Best Fertilizer for Viburnums

Many viburnums produce single-seed fruits.

Many viburnums produce single-seed fruits.

With white flowers and attractive leaves, viburnum plants -- usually shrubs -- add color and life to a garden. Some varieties are fragrant, and their small berries also provide a feast for hungry birds. Many types are hardy to U.S. Department of Agriculture plant hardiness zones 2 through 9. Though partial sun and regular watering are the most important ingredients for viburnums' health, fertilizing can also encourage healthy growth and flowering.

Soil Tests

Before applying fertilizer, test your soil to determine what nutrients it has in abundance and what it's lacking. Garden supply stores sell home soil-test kits, or you can hire a professional to test the soil. To give viburnums a better chance of succeeding, correct nutrient deficiencies in your soil before planting. Performing a soil analysis every two to three years after planting is a smart way to make sure your viburnums and the rest of the garden are receiving all the nutrients they need.

Soil pH

Soil can be acidic or alkaline, which affects how your plants absorb nutrients. The pH scale measures this, with 7 indicating neutral soil; the number decreases with acidity and increases to indicate it's alkaline. Viburnums grow healthiest in neutral to slightly alkaline soils, with a pH balance around 7 or slightly higher. If your soil test indicates that your soil has a different pH, you'll need to fertilize to correct this. Applying common sulfur lowers pH, while ground or powdered lime or limestone increases pH. Because it takes a long time for the ingredients to break down into the soil, the process of changing your soil's pH balance may take months or years.

Balanced Fertilizer

Viburnums appreciate an annual application of a balanced fertilizer in spring. A balanced fertilizer has an equal ratio of nitrogen, phosphorus and potassium, which should read 10-10-10 on the label. The nitrogen helps viburnums grow lush foliage, while the phosphorus encourages healthy root, stem, flower and fruit growth. Potassium helps viburnums and other plants absorb those nutrients. If using granular fertilizer, sprinkle the granules on the dirt above the roots, then water to flush the fertilizer through the soil.

Organic Fertilizer

If you prefer to apply organic matter as fertilizer instead of premade, commercial fertilizers, you have plenty of options. At planting, you can add bone meal to the soil to give roots and new growth a boost of phosphorus. Later, alfalfa meal, compost, rotted manures and fish emulsion are all safe choices for fertilizing viburnums. Blood meal is a smart choice to apply in late winter or spring, as it breaks down rapidly to sweeten the soil for flowering.

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