Can you really "burn a lawn" by watering when the sun is shining on it?
 

I have recently read that you shouldn't water at night because it
promotes fungus. It is presently almost 100 degrees here during the
day so I am afraid of watering then because I have heard that the sun
will burn the grass. Any advice on this topic would be welcome. Also
I would appreciate any tips on watering ammounts in this environment.
My zip code is 92405.

Thanks,

Mike

wrote:
I have recently read that you shouldn't water at night because it
promotes fungus. It is presently almost 100 degrees here during the
day so I am afraid of watering then because I have heard that the sun
will burn the grass.


If the hose has been sitting in the sun, any water actually in the hose
could get warm enough to cook a little grass, but once the water in the hose
has been flushed-out, and you're getting the fresh stuff from the faucet,
that risk is gone.

And no, the little droplets of water on the grass do not turn into
magnifying glasses, and focus the sunlight. Part of that magnifying glass
burning something paradigm is that the magnifying glass can't be touching
what it's supposed to be burning. There's no room for the rays to be focused
if they don't have to travel far after entering the lens.

The problem with watering in full sun is evaporation. Some water evaporates
before it even comes back down to the ground - especially if you have a fine
spray. And of what lands on the grass, too much evaporates before dripping
down to the soil, and being soaked-up. Remember, you're trying to water the
soil so the water gets to the roots. Spraying water on the blades of grass
does no good.

The best time to water is to finish watering around dawn. But if you're
getting 100 degree days, unless you're dropping down into a humid 60's
overnight, you probably won't need to worry too much about fungus. Still, a
$20 timer can solve the problem, and start the watering while you're still
sleeping, and you'll never forget to turn it off, either.

--
Warren H.

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