Question
Hi Kenneth:
I live in Detroit,MI and I have kentucky bluegrass. I notice that my lawn is turning brown I cut it at a high setting . I read that i should water the lawn long enough to get a inch of water per week. I am wondering is this enough water especially here in michigan the weather here is in the upper 80's. or should I stick with the once a week watering.

Answer
A kentucky bluegrass lawn can suffer from heat stress in the heat of summer and slightly browning is not usually a problem. when cooler temperatures return the lawn will green back up.

During very hot summer months a cool season lawn will go partially dormant. This is a protective mechanism to ensure that the grass does not deplete the carbohydrate reserves. Once cooler temperatures comes around it usually greens back up again. Even a cool evening will turn it green immediately.


A lawn should be watered infrequently but deeply when you do water as opposed to frequent and shallowly. One deep application of water per week is preferred to many daily shallow applications.

During very hot summer months you can water twice per week if you find that the lawn is not staying green, but when you water you should still water deeply.

Watering more that than is not going to make a difference any way. The goal is to make sure that the lawn gets enough water without experiencing draught stress. watering deeply once or at most twice per week will ensure this. If the lawn is still turning brown then it is not draught stress. It may be heat stress as mentioned above, or could be insect or fertilizer damage. Browning due to heat stress is very common, and it will disappear again.

Normally it takes a oscillating sprinkler attached to a garden hose using regular household water pressure about 2 hours to put down enough water to thoroughly wet the root zone to a dept of 8-10" which is the recommended watering pattern.

You can check how much water your sprinkler system puts down by placing empty cans in the sprinklers path (tuna cans, empty food cans, etc. The cans should have a straight side, e.g. like a box, not tapered like a vase).

Turn the sprinklers on and let them run for 30 minutes. turn them off (or you will get wet) and meassure how high the water is inside the cans. If the height is 1/4" then you need to water 4 x 30 minutes = 2 hours to apply 1" of water.
1 inch of water per week will wet the root zone to a dept of 8-10" which is the recommended watering pattern.

People generally misunderstand how much an inch of water is. It often takes at least 2 hours to apply 1 inch of water in one watering application.

Otherwise:
- continue to mow high as you have been doing
- fertilize your lawn in late spring, early fall and late fall. avoid fertilizing your lawn too early in spring and do not fertilize during hot summer months. I recommed that you fertilize your lawn in late May, late August and late October.

Finally, if the lawn is turning brown in specific spots you should check for insects. Grubs can be found by cutting into the lawn with a shovel and going through the root zone. If you find more than a few c-shaped white maggits you should apply Grub-Ex now. Any turf you lift can be replaced and just water that spot daily for 14-21 days to ensure re-rooting.

The tell tale sign of grubs is that you can lift dead grass up by grapping it (like a carpet you lift off the floor).

Good luck