re: Deep green Bermuda (correct board)

Growth regulator limits vertical growth. Grass becomes thicker, denser, and healthier in some ways. If you're mowing below an inch it helps to keep you from having to mow every 2-3 days.

You end up applying it every 2-4 weeks dependent on what your daily local temps are(most people use a calculator). A lot of people spray iron and nitrogen/urea/ammonium sulfate at the same time.