These are cool season grasses and go dormant in heat -- you're probably seeing "leaf
firing". Continue to water, but do not overwater -- things will green
up again when fall comes.

Just what is "leaf firing," Kay?

The leaf goes yellow, starting at the tip and working back to the base.
As opposed to the yellow streakiness you see if the grass is starved for N.

Perhaps I'll try cutting back the watering to twice a week, watch the
lawn closely, and see if that helps at all.

Do dig down in a spot and see how far your water is penetrating. There's
no point in only watering the top inch of soil when the lawn is established...
that actually will increase your chances of problems with the lawn. Instead,
a good, deep soaking once a week is better... in the upper midwestern summers,
we figured an average of 1" of water a week to keep a bluegrass/fescue lawn
going. Luckily, in the midwest, you usually get that inch in rainfall.

I cannot, in good conscience, put an inch of water on my lawn out here in
the arid west (I'm near Portland, OR), so I'm maintaining a bit of lawn near
the house (my DH is a traditionalist) and slowly working on converting the
rest to native plants, which do not need summer watering. The lawn near the
house, however, just gets enough to keep it barely alive in the summer...
nowhere near enough to keep it green.


Kay