Do I need to use fertilizer on my crepe myrtle?
The short answer is no. Crepe myrtles are well adapted to poor nutrient soil and so fertilizer is usually not necessary and might even have a negative effect on your crepe myrtle. That being said, fertilizer can be beneficial for certain situations as long as it is used sparingly.
So when is it beneficial?
To put it simply, you should use fertilizer when you want to promote lush growth in your crepe myrtle. But isn’t lush growth always a good thing? Not always, if you use too much fertilizer your crepe myrtle will be too busy making new green growth and may not bloom as well. All this new green growth is also very susceptible to cold, so it reduces the cold hardiness of your crepe myrtle. Fertilizer is best used when your trees are planted in extremely poor nutrient soil or if you have older plants that have slowed their growth.
What kind should I use?
If you do decide that your crepe myrtle will benefit from fertilizer, you should use a moderate amount of 5-10-5 fertilizer (5% nitrogen, 10% phosphorus, 5% potassium). Remember you don’t want to use very much, these trees thrive in nutrient poor soil. If you are fertilizing other grass or plants around it you should probably just skip fertilizing the crepe myrtle.
When should I fertilize my crepe myrtle?
You should fertilize your crepe myrtle at the start of the growing season. That usually means early to mid spring. This allows your crepe myrtle to harden any new growth from the fertilizer in time for the winter.