When to Fertilize a Perennial Flower Garden

Planting

• Add fertilizer to soil before planting perennials in the spring. Soil tests will tell you exactly what your garden needs. If you haven't done soil tests, University of Illinois Extension recommends approximately 2 lbs. of 5-10-5 fertilizer per 100 square feet of flower bed. The numbers indicate the percentages of nitrogen, phosphorus and potassium in the fertilizer.

Maintenance

• After a perennial flower garden is established, fertilize in early spring if necessary. North Carolina State University Extension recommends repeating the application in mid-summer. If soil tests aren't available, 2 to 3 lbs. of 5-10-5 or 10-10-10 fertilizer per 100 square feet of flower bed in spring and 1 1/2 to 2 lbs. per 100 square feet in the summer is recommended.

Considerations

• Watering flower beds after fertilizing will keep foliage from burning and makes the fertilizer available to the plants more quickly. Fertilizing in the fall is not recommended because plants need to shut down for the winter. When in doubt, use less fertilizer rather than more. Over-fertilizing will result is more foliage growth and possibly an increase in disease, while decreasing flowers.