How often should I fertilize perennials?

Question:

How often should I fertilize perennials?

Answer:

For most perennials, an application of 1 to 2 pounds of an all-purpose garden fertilizer per 100 square feet is adequate. Excess fertilization produces weak, leggy growth and inhibits flowering. Early spring (late March to mid-April) is the best time to fertilize perennials in Iowa.