Healthy lawns are things that when green and healthy, we can perhaps not give it too much attention. But, with a bit of green or brown, the lawn is suddenly very important. We want it green and full. Does that healthy lawn affect the environment negatively?
Lawns can sometimes take a bad rap. In fact, a healthy lawn can reduce runoff from rain or irrigation. The lawn-slowed water allows the water to saturate into the soil and root zone below. Healthy turf does have its benefits. You can conserve water and save yourself some money too!
Irrigation and Calibration
Your irrigation system should be set at “off” most of the time. You should water your lawn just as it is showing wilt, i.e., the grass blades are folding slightly and your foot prints may show in the lawn and don’t lift back up. Watering when you lawn really needs it will result in your lawn to growing deeper roots and and being more drought resistance. If you irrigate your lawn two times per week automatically during the growing season, you are training your lawn to grow shallower roots. You want a deeply-rooted lawn in the event there are any water restrictions. Irrigate no more than one-half to three-quarters of an inch per watering applied one time a week when dormant and no more than two times per week during the heat of summer.
To determine if your irrigation is providing that much at each watering, you need to calibrate your system. Set clean tuna cans or mini-rain gauges throughout a zone at a time and let your irrigation run that night as long as it would typically run. Check the tuna cans in the morning to see if your irrigation system has supplied one-half to three-quarters of an inch of water. Adjust the time of irrigation in each zone as needed to provide the required amount of water. Try it in your other zones. You only need to do this one time per year.
Fertilization and Calculation
Another way to have a healthy lawn without adversely affecting water quality is to fertilize correctly. Start with a soil test to check pH and nutrients. Often our soils do not require phosphorus, so you could use 15-0-15, or 15% Nitrogen, 0% Phosphorus and 15% Potassium. You could also consider 16-4-8. Those fertilizers have a 1:1 or a 2:1 ratio of Nitrogen to Potassium. Avoid high nitrogen fertilizers as well as weed-n-feed formulations anytime during the year.
If you have chosen a fertilizer that is all quick release, the most nitrogen that you can put down at a time is one-half lb. N per 1000 square feet. If you use a fertilizer that is that is at least 30% slow release (either coated or water insoluble nitrogen), you can use 1 lb. of nitrogen per 1000 square feet. Do not apply more than recommended at each application. More than .5 pound of “quick release” N fertilizer cannot only potentially damage your turf but will move through the soil and have potentially negative impacts on water quality.
Calculate how much fertilizer to use by using your Nitrogen number. If using a 15-0-15 slow-release fertilizer, divide 100/15 = 6.67 pounds of fertilizer for 1,000 square feet. If you are spreading your fertilizer over 3,000 square feet, you would multiply the 6.67 x 3. You would apply 20 pounds for the 3,000 sq. ft.
Just a few last thoughts on achieving your healthy lawn. Mow your lawn at the correct height – maintain Floratam St. Augustine turf at 3.5 to 4 inches, ProVista St. Augustine at up to 3 inches, Bahia at 3.5 to 4 inches, and Empire Zoysia maintained at 2 to 2-1/2 inches. Lawn mowed at the correct height will hinder weed growth. Additionally you should not take off more than 1/3 of a blade at a time. That can result in a reduction in roots, negating all the efficient irrigation work!
For more information on Florida lawns, visit this Florida Lawn Handbook link at https://edis.ifas.ufl.edu/entity/topic/book_florida_lawn_handbook_3rd_ed. For troubleshooting turf, visit plant clinic Zoom! Check out the calendar for the zoom links to virtually visit an Ask the Master Gardener Plant clinic.