Home > Great Big Greenhouse Blog > July 2015 > BONNIE'S GARDEN--Gardening in the Heat

BONNIE'S GARDEN--Gardening in the Heat

Keeping our vegetable gardens watered in the heat is one thing; however heat does cause a few problems.  First, powdery mildew loves hot humid weather and can be a problem—particularly this time of year when our young vegetable plants are now mature and there is less air circulation around them.  (This is why I always try to space my plants as far apart as I can.) 

There are many types of powdery mildew, so just because it shows up on your squash, that variety of powdery mildew will not affect your roses.  Cucurbits (cucumber family members) are particularly vulnerable so look for little white powdery spots to appear.  Eventually those spots will grow to cover most of the leaf.  Powdery mildew thrives on new tender grown, so if it shows up, avoid applying fertilizer until you have gotten it under control.  Believe it or not, a mixture of 10% milk (one part milk to nine parts water) seems fairly effective against powdery mildew when it first appears.  Neem oil can also be used but be sure to spray when temperatures are below 90 degrees to avoid damage.

Some vegetables—particularly beans—will abort their flowers when temperatures reach into the 90’s.  Other vegetables—tomatoes, pepper, and eggplants, in particular—will have trouble setting fruit because heat can damage the pollen.

If heat persists, you may even want to invest in a light shade cloth to give your plants a break—be sure to suspend it about a foot or so above your plants so as to allow plenty of air circulation.  And I probably would not use it if I had a problem with powdery mildew.
And, be sure to keep your garden weeded –yeah, it’s a lot of fun in the heat (more about how to keep US cool in minute.)  Plants, already struggling with the heat, shouldn’t have to compete for water or nutrients, too.

Now, about US!  I read somewhere that when the temperature and humidity numbers added together equal more than 160, we should stay indoors.  That can be hard to do—unless you like gardening by moonlight.  So I make sure I wear a hat or visor, apply a sweat-proof sunscreen and I often tie a wet bandanna around my neck or drape a wet hand towel around.  At work, I keep a wet hand towel in an insulated lunch bag with some ice.  Keeping TWO and swapping them out would be better, if I remembered to bring that second hand towel to work.  Oh, and of course, I try to stay hydrated!
Posted: 7/20/2015 by Bonnie Pega | with 3 comment(s)
Filed under: Bonnie's, Garden, Gardening, Heat, Mildew, Powdery
It's been a good year for cucumbers in my garden, too. I don't know exactly why the milk spray works (might be that it changes the pH of the surface) but it does. Keeping an eye out for insects which can transmit disease is the best way to keep from getting it because, once you have it, it's a whole lot harder to get rid of it.
8/1/2015 11:38:13 AM

Bruce Byers
Thank you for this helpful information. So far, no powdery mildew. However, I have sprayed against mosaic cucumber virus and the insects that transport it around cucumber leaves. Lots of cucumbers now. Green beans are growing but won't begin bearing fruit for another month (I planted late). Have had powdery mildew in the past and usually have cut and discarded the leaves. I'll try the diluted milk solution. Perhaps it's the lactic acid that help kill the fungus.
7/29/2015 3:34:19 PM

Barb Lynn
Thank you so much for explaining the powder stuff on my squash. I have had a problem with the famous squash bug so I tried to grow the squash indoors. Yet I saw the powdery stuff and the squash plants I got died. So I will try the cure next time but I still might plant a few squash seeds and see what happens.

7/26/2015 6:48:10 PM

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