Crepe myrtles grow in low-nutrient soil. You can fertilize them, but it is usually not required. Fertilize a crepe myrtle plant at the beginning of the growing cycle to promote lush growth. Use 5-10-5 fertilizer sparingly.Continue Reading
Find and buy fertilizer with 5 percent nitrogen, 10 percent phosphorus and 5 percent potassium.
Fertilize the crepe myrtle in the early to mid-spring. Follow the directions on the fertilizer packaging.
A crepe myrtle grows in poor soil, so it will not require large amounts of fertilizer. Fertilizer is generally not required, and too much may deter the crepe myrtle from blooming.