Find ways to shade your plants from the blazing sun

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By Jeneen Wiche

I can’t believe this heat already. I was hopeful this summer was not going to be a repeat of last but it looks like we are on track for some serious heat this summer.  Some vegetables will surely respond to temperatures in the 90s … some will be good and some will be bad. I know we can’t change the ambient air temperature on a 90 degree day, but we can provide some shade for our plants on the hottest days of the summer with reasonable results.

The vegetable garden can start doing some funny things during a heat wave.  When temperatures start to raise into the upper 80s and 90s, many vegetables drop flowers before pollination and fruit set and stop blooming. Beans, tomatoes and eggplant do like it hot but there is a threshold of tolerance to heat; ideal temperatures for maximum performance is about 86 during the day for these summer vegetables.   

The heat will also make other crops bolt and become bitter. Spinach, peas, and cole crops such as broccoli, Brussels sprouts and cauliflower prefer the cool temperatures of spring and fall and make haste to flower and go to seed when temperatures rise. The current weather may do them in for the season. 

Tender lettuces will bolt, too. My second round of summer lettuces (varieties more suited to the heat, including bolt-resistant Jericho, a Cos type called Pandero and a “heat wave” mix from Cook’s Garden) is just coming in. The summer lettuces can stand some heat but will last longer if I alleviate some of the stress. 

The fruit of some crops can get sun burned, as well, when temperatures are high.  Sunscald is common on ripening tomatoes, especially if the plant is a little diseased and the foliage isn’t adequately shading the fruit on its own.  Think about all the crops that tuck themselves beneath the foliage of the plant … all of these will get sunburned if left otherwise exposed on a 90-degree, full-sun day.  This is where we can step in and help out with some strategically placed homemade shade devices. 

Providing a little shade will go rather far when temperatures rise into the 90s and you may want to consider it throughout the garden.  You can use lattice work, old screens, shade clothe, old sheets, fine netting or mesh (like what you would use for a wedding veil). 

Concrete blocks, bricks or terracotta flower pots can provide the base for a screen to rest on several inches above a low-growing crop like lettuce.  A picnic table bench works great as a prop for a screen set on a slant on the south side for crops that are medium-height; and using a shade clothe tied to four bamboo stakes can shade anything at any height from above or on a slant depending on the length and placement of the stakes.  You get the idea.

We have had plenty of rain this spring so there is adequate moisture in the soil for now; however, the high heat will make plants transpire moisture through their foliage at a faster rate then they can take it up through their roots. Wilting because of this transpiration may occur, which doesn’t necessarily mean the soil is dry. If a plant recovers overnight then you know that the wilting was caused by rapid transpiration, not thirst.  Extra shade will help offset this; and, if you never mulched your vegetables now would be the time to reassess that decision.  Mulch helps keep the soil moist but it helps keep it a bit cooler, too.

Another thing the hot weather may do:  if you love hot peppers, get ready for hotter than you anticipate.  Heat makes hot peppers hotter; it makes chickens lay fewer eggs, hair grow faster and crime go up.  Hopefully, the heat wave won’t last too long. I’ll enjoy the extra heat in those peppers, at least.