Applying a high nitrogen fertilizer to warm-season annuals four to six weeks after flowering can promote more vigorous growth and a longer blooming season. Implementing a regular fertilization program every three to four weeks is important if your garden receives regular irrigation or during a rainy summer.
Common sources of nitrogen-only fertilizers include nitrate of soda, urea and ammonium sulfate. Blood meal is an organic fertilizer that contains nitrogen. Use one of these fertilizers at the following rate:
Nitrate of soda (16-0-0): Apply 1/3 pound (.75 cup) fertilizer per 100 square feet
Blood meal(12-1.5-.6): Apply 7 ounces (7/8 cup) fertilizer per 100 square feet
Urea (46-0-0): Apply 2 ounces (1/4 cup) fertilizer per 100 square feet
Ammonium Sulfate (21-0-0): Apply 4 ounces (1/2 cup) fertilizer per 100 square feet
Alternatively, a lawn fertilizer that is about 30 percent nitrogen (nitrogen is the first number listed in the series of three) can be applied at a rate of 3 ounces (3/8 cup) per 100 square feet. Do not use a fertilizer that contains a weed killer or weed preventer.
Cynthia Domenghini, Extension Agent
