Food Gardening in a Heat Wave

Heat-damaged blueberries

Last week, we watched the weather forecast with dread.

Extreme heat was on the way. The forecast started out predicting highs in the low 90s—dauntingly warm for June here on west side of the Cascade Mountains. A day later the mid-90s were predicted, and the day after that, the high 90s—which was even more freakish for our area. 

The cause was an enormous “heat dome” over most of the West, extending into Canada. You'd have to travel long and far to escape it. But what if road pavement or airport tarmac melted?

Not that it would ever occur to me to leave our place, no matter how hot is got. But my anxiety was building. How would our food crops—accustomed to temps in the 60s and 70s this time of year—get through such heat?

By the time the real hot weather arrived, the forecast went from nerve-wracking to frightening: in two days, it would be a sweltering 107 degrees.

Now I understand that to lots of folks out there, in the American West and Southwest, and many other parts around the globe, 107 degrees is no big deal. You’re either accustomed to just enduring the heat, or you turn up the air conditioning. But here on the west side of the Cascade Mountains, temps like that are unheard of. Few people or businesses—and that’s VERY few—have A/C. And pretty much no one is used to extreme heat.

I had never experienced heat like that, and I'm from the Midwest. But I was more worried about our food crops—we’d had nice rainfall the first couple of weeks of June, so I hadn’t started watering the garden yet. And most of our veggies were seedlings, newly germinated or newly transplanted. Our berries had great fruit set, and were starting to ripen. I had no idea if they could survive temps over 100.

I had to get my head around the thought that we could lose everything—our entire food crop. Not just for the season—maybe we would even lose all our food plants.

And what about the hens? We could lose them too.

They’d never experienced heat like this. I had no idea if they could develop a chicken version of heat stroke. They did have lots of shade to range in, and John filled their waterer to the top.

I was concerned for all the farmers/fruit and vegetable growers in our area. I had no idea how raspberries and blueberries, two of the biggest crops in our county, would fare, or the dairy cattle either.

I was very worried about the wild songbirds too—they weren’t used to this heat either. We set out water for them, and all we could do was hope for the best, for plants and animals.

Feeling bleak, I knew I had to at least try to see what we could save in our garden. I hauled out the hoses and got started. We don’t have soaker hoses or any other kind of watering system, so I wouldn’t be able to get everything watered. So I worked on a priority basis.

Blueberries: They have surface roots so they got first crack at the water. I had already heavily mulched them with wood chips, so I hoped they could survive.

Strawberries: Even if the plants survived, I didn’t know if the berries would make it. 

Veggies: I’d removed the winter mulch off the beds for seeding, so the seedlings had no heat protection at all. I got the beds newly mulched with leaves and compost, then watered it in. Then I covered our most vulnerable root crops—tiny carrots, parsnips and beets—with row cover.

The newly germinated squash, I mulched with brackenfern from the woods, to add some moisture to the soil before the fern fronds dried out. 

I had some tree prunings from the maples right next to the house, and I set those on the potato beds.

Caneberries: Marionberries are our favorites so I keep them well mulched year round. I watered them first. The others would have to wait their turn.

The first day of the wave was around 98, and the humidity was off the charts. It was too hot to work outside, so John and I would stay in until 8 pm or so, then frantically start watering until dark, around 10. As we worked, the mosquitoes were savage—clouds of them, biting you through your clothes. That’s also very unusual, mosquitoes generally aren’t a problem around here. The air was completely still and felt so wet you could wring it out like a dishrag.

The next two days were awful: Day 2 it was around 103, and Day 3, 107. Our outdoor thermometer, getting the heat bounce off the house, read 116. Whatever the real temperature was, all we could do was water the crops and slap at mosquitoes until we were exhausted. Poor John had 22 bites (I counted) on his left elbow alone.

Day 4 arrived…and with it, a breeze. The high would be in the high 80s. Perfect weather to me is around 70 degrees, but I was never so grateful for 88 degrees in my life. Now I had to assess the damage.

The veggie seedlings, with daily watering, came through like champs under the row cover. Likewise the squash babies, with their mulch. The new tomato transplants got burned leaves, but lots of healthy green growth.

I didn’t get a chance to water couple of beds of bolted spinach. The plants mostly fried and won’t reseed. Some ornamentals like coral bells fried too.

Strawberries: lots of melted or partially burned berries, and some sunburned leaves, but they were otherwise okay.

The marionberries, which hadn’t started ripening yet, also champs of the heat wave.

Happy bee balm

And our favorite ornamentals/treats for pollinators, the bee balm, seemed to actually thrive.

The greatest damage was to my beloved blueberries: tons of berries just fried. The result was wilted or melted berries in a sickly shade of beigey-pink. (See above pic.) Lots of growing ends were terminally sunburned. But the shrubs themselves still seemed all right.

Interestingly, a shrub just kitty-corner from the one with the fried berries showed no sign of heat stress. Which tells me that some varieties are more heat-tolerant than others.

Healthy, undamaged blueberries

And the birds? The hens surprised us—and did absolutely great. Their appetites were down, but they laid every day through the heat.The songbirds continued to sing! (Though not in the afternoons.)

As the days go by, I may just be beginning to see the damage. I’ve noted lots of burned foliage on native plants—vine maple, red current, and alder trees. Our lovely grand fir, that we transplanted from the woods, has hundreds of burned ends.

However,  Nature, I’m discovering, is resilient. I just hope the local farmers didn’t lose too much of their crops.

One thing that I’m sure of, is that this heat wave isn’t a one-and-done hot spell. I heard from someone that our region had temps 35 degrees above normal. Temperatures like this could happen again.

The key to giving your food garden the best chance of survival, is to be prepared. Keep your food crops well weeded, so your crops don't have to compete for water. Then throughout the summer, mulch and water, water and mulch. 

You'll find lots of info about mulching in my free gardening guide, Little Farm in the Garden, available at Amazon, Apple, Kobo and all other online bookstores!