{"id":3878,"date":"2018-07-12T21:53:52","date_gmt":"2018-07-13T04:53:52","guid":{"rendered":"http:\/\/gregalder.com\/yardposts\/?p=3878"},"modified":"2021-06-11T20:44:34","modified_gmt":"2021-06-12T03:44:34","slug":"caring-for-your-garden-during-a-heat-wave","status":"publish","type":"post","link":"https:\/\/gregalder.com\/yardposts\/caring-for-your-garden-during-a-heat-wave\/","title":{"rendered":"Caring for your Southern California garden during a heat wave"},"content":{"rendered":"\n

That last one was a scorcher!  In Santa Ana, it set an all-time record at 114. In Riverside, it got up to 118. Ojai hit 110. In the shade of my front porch in Ramona, San Diego County, it reached 113. July 6-8, 2018 was a spell for history. <\/span><\/p>\n\n\n\n

It was so hot that it burned native live oak trees. Never seen that before.<\/span><\/p>\n\n\n\n

As far as the garden goes, I won some and lost some. I have seen and heard from many others up and down Southern California who had the same results — the exception being anyone who lives within a couple miles of the beach. They only heard about the inland heat.<\/span><\/p>\n\n\n\n

This post is about what we\u2019ve done right and wrong in caring for our vegetables and fruit trees during the intense heat. The goal is to help us get through the next heat wave better.<\/span><\/p>\n\n\n\n

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Water<\/strong><\/p>\n\n\n\n

First and foremost, water everything, and do so <\/span>before<\/span><\/i> the heat wave hits. Compare two of my grapevines. I had watered this young grapevine deeply just before the heat hit on Friday, July 6. It took the 113-plus-degrees in stride.<\/span><\/p>\n\n\n\n

\"Young<\/a><\/figure><\/div>\n\n\n\n

But I didn’t get around to watering this grapevine until the heat was already upon it. Obviously, this was too late.<\/span><\/p>\n\n\n\n

\"Young<\/a><\/figure><\/div>\n\n\n\n

I\u2019ve seen this strategy of watering thoroughly <\/span>before<\/span><\/i> the heat hits work very well on any and all vegetables and fruit trees during this last heat wave as well as during previous heat waves. It just works. I know this much firsthand.<\/span><\/p>\n\n\n\n

Why does it work? As one University of California soil scientist and irrigation expert explained it to me, when the heat gets severe the plant is unable to take up water through its roots — just when it needs that water most. The plant stops transpiring (exhaling water from, mostly, its leaves), which is necessary in order to draw water into its roots. In essence, the plant shuts down.<\/span><\/p>\n\n\n\n

However, if the plant had had ample soil moisture available to it before the severe heat hit, then the plant would have fully hydrated itself and be as fortified as possible to tolerate the heat and suffer as little damage as possible while it was shut down. You are preloading the plant before the stress.<\/p>\n\n\n\n

It’s akin to the advice your mother gave you to eat a good breakfast before<\/em> you start a busy day.<\/p>\n\n\n\n

Secondly, water <\/span>some<\/span><\/i> plants <\/span>during<\/span><\/i> the heat wave. In my experience, most vegetables and avocados usually need irrigation daily when the mercury rises into triple digits. This was certainly required with last week\u2019s record heat. For the most part, this is because most vegetables and all avocados are relatively shallow rooted.<\/span><\/p>\n\n\n\n

In contrast, I watered my citrus trees just before the heat and found no need to water them again during the heat. Same with peaches and plums and other deciduous fruit trees. I felt the soil under all of these trees amidst the heat wave and found it still plenty moist. <\/span><\/p>\n\n\n\n

Beware of any trees on drip irrigation though. They’re likely to need daily water when it’s 100 since trees on drip irrigation generally have limited root systems.<\/span><\/p>\n\n\n\n

One last thing: Wetting a plant’s leaves gives it relief from heat stress. If you’re around and able to do it, then spray down the foliage of plants that are wilting even though they have moisture in the soil below; you’ll see them perk up immediately.<\/p>\n\n\n\n

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Shade<\/strong><\/p>\n\n\n\n

Protect plants by shading them if you can. Use whatever is on hand: a chair, a table, a beach umbrella, a tomato cage covered in shade cloth. This baby avocado tree came through the intense heat perfectly because I shaded it:<\/span><\/p>\n\n\n\n

\"Jan<\/a>
During the record heat.<\/figcaption><\/figure><\/div>\n\n\n\n
\"Jan<\/a>
After the record heat.<\/figcaption><\/figure><\/div>\n\n\n\n

Other larger avocado trees were impossible to shade, and some of their leaves burned despite the plentiful water I gave them. Avocados are not built to withstand 110-plus degree heat and low humidity.<\/span><\/p>\n\n\n\n

Here are the crispy leaves of an adjacent avocado tree that I didn’t shade:<\/span><\/p>\n\n\n\n

\"Nimlioh<\/a><\/figure><\/div>\n\n\n\n

(For avocado-specific guidance see my post, “Protecting avocado trees from heat.”<\/a>)<\/p>\n\n\n\n

Here is a video tour of some of my avocado trees and the damage they incurred on July 6 and 7, 2018:<\/span><\/p>\n\n\n\n