What is the best way to care for new grass in 90 degree weather?

If you have tiff type grass water the grass about every 3 hours for 10 minutes each watering cycle during the day. Do this for 7-8 days when the grass is new. If the water is pooling shorten the watering cycle by 2 minutes until the pooling stops.

Once the first week has gone by move the watering to once every 5 hours for 5 minutes each cycle. Do this for another 7 days. Once this 2 week period is over your lawn should be ready to mow for the first time. Make sure your mower is on the highest mowing level. This first mowing will help the grass grow back faster and thicker.

For the third week change the watering cycle to 2 times per day for 7 more days (8-10 min. each watering). After this your grass should only have to be watered 1 time per day 8-10 min. each time or 15 min every other day. The second option is better for tiff since it causes the grass to make it's roots dig deeper.