As temperatures rise to around 90 degrees, cool season grasses will decrease root growth and blade growth and go relatively dormant. If you have followed our watering schedules you should be able to keep your lawn green while watering 1″ every 6-7 days. Fertilize around Independence Day. It is acceptable, even beneficial, on a bluegrass lawn to let it go gray or even brown in the heat of the summer. This dormancy will shock the roots and cause them to start storing more water. Rye and Fescue lawns do not rebound as quickly from dormancy.
As temperatures start to cool a little you will see increased blade growth. No need to fertilize this month but make sure you stay on top of weeding, either by hand or herbicide. With the lawn coming out of dormancy, weeds will have an easier time breaking the natural weed barrier created by a strong root base. You should be able to cut back your water to 1″ every 7-10 days as the weather continues to cool. Remember that you should never cut more than 1/3 of the blade off when mowing your lawn. Doing so will prevent shock and will require less water to regrow.
Time to fertilize again, sometime around Labor Day. Using a fertilizer high in nitrogen, which includes iron, will help with green up (if you are having green up problems). If you see a lack of green choose a balanced fertilizer (16-16-16) in order to promote health of blades, roots, and cell structure. Also, if you have weed problems, this is probably the last time that a herbicide will work effectively. Choose a pre-emergent to prevent weeds in the spring, or a post emergent if you are worried about weeds you currently have in your lawn. As temperatures continue to cool and we see more moisture, you should be able to cut back to 1″ of water every 10-14 days.