Heat Waves and Watering

 We are at the end of a 90+ degree heat wave waiting for it to break and cool back down to the 70s tomorrow.  It was 93 degrees in the shade yesterday, and this morning at 9:30 it is already 90 degrees with 60% humidity.

 During an unseasonable heat wave, you have to keep an eye on your water.  You don't want to over water because you can kill a plant quicker with too much water than you can by underwatering. It is hard to take water away once you realize you over did it.  When the forecast shows heat coming, and we have not just had rain, I will go through and do a deep watering so everything is hydrated ahead of time.

 I like to check the condition of my plants in the late afternoon.  If any are showing stress at that point, I will know they need water the next morning to prepare for the next hot day.  I prefer to water in the morning so the sun can dry the leaves and the water is readily available for the coming sun. If I have let it go too long and they are very wilty in the afternoon, I may decide to water right then to rescue them (especially container plants that will not have the resources to recover over night).  But the idea is to know what is happening so you can time your watering for the next day.

This is what I am watering today.

Early peas flowering and filling out pods.
These are showing heat stress (yellowing) so I have watered them deeply the past two mornings.
The soil is moist today so I just watered lightly to cool the lettuce.

Later peas showing no stress but filling out pods so we want those pods to be nice and plump.  I am watering enough to keep the soil consistently moist.

Pole beans just putting out new climbing growth.  People will dismiss the water sun scald as a myth.  In most cases it is.  If you water these broad leafed beans in the sun, they WILL scald.  But that won't hurt them much.

Water scalded leaves from watering yesterday. 
I think that laying on steamy, moist soil does most of the damage.

Strawberry plants showing heat stress (curling leaves)
They were watered two days ago and got water again today.

I made sure the tomato reservoirs were filled two days ago (bottom watering), but this plant gets a little extra water because it is setting blooms today and has a wide leaf more susceptible to heat wilt. 

Potato grow bags.  These dry out quick.  They were deeply watered the past two days.
I will check them mid day and water any one that is starting to wilt.

Not watering today.  I watered them deeply two days ago and the soil still feels moist.

Not watering Dahlias.  They will wilt a little but will recover.
This will encourage them to dig a little deeper for moisture and strengthen their roots.  Watering today would likely scald the broad lower leaves and do more damage than dryness.

Plants in small pots need water every day and sometimes twice a day.

I watered my large containers deeply the first morning and they should be fine

Everything should be prepared to survive day two of ninety degrees and high humidity.  At some point, the humidity becomes a bigger problem because it promotes mildew.