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The Spokesman-Review Newspaper
Spokane, Washington  Est. May 19, 1883

In the Garden: Gardeners adapt to the heat wave in Spokane and elsewhere

Many gardeners, including Susan Mulvihill, used shade cloth to protect some of their vegetable crops from the intensity and heat of the sun during recent extreme temperatures.  (Susan Mulvihill/For The Spokesman-Review)
By Susan Mulvihill For The Spokesman-Review

In the 40-plus years I’ve lived in Spokane, I have never experienced temperatures between 105 and 111 degrees. Add an extreme drought on top of that, and gardens will struggle.

When I first learned of the forecast, I was in a state of disbelief, but once those high temperatures arrived, a sense of panic washed over me. It turns out I had plenty of company because emails from concerned gardeners started flooding in.

Here’s what Bill and I did to try to lessen the impact on our vegetable garden: This time of year, our drip irrigation system runs 10 minutes in the morning and early evening. We had to double that time, plus we hand-watered some of the vegetables that still wilted from the heat.

I watered all container-grown plants multiple times a day, and we placed shade cloth over our three tomato beds and the pepper bed to cut down on the intensity of the sunlight.

Before the heat wave, our corn plants were on track to be waist-high well before the Fourth of July. The foliage was lush and deep-green. After a couple of days of intense heat, the plants stopped growing, and many upper leaves burned to a crisp.

The tomato plants didn’t care for the heat at all. Their leaves curled upward, a condition known as “physiological leaf roll” in response to the temperatures.

Instead of seeing flowers and young developing tomatoes, I was greeted by the sight of very unhappy plants. The peas and lettuce shut down, but that is customary for those cool-season crops.

The summer squash plants decided the heat wave was great, putting on lush green growth and cranking out so many zucchinis that a trip to the food bank is on my list of things to do. The winter squash grew by leaps and bounds, as well.

How did Northwest gardeners – as well as those who are also experiencing heat waves elsewhere – handle the challenges?

Spokane Valley resident Marilyn Brady Carothers experienced mix results in her garden. “The snap peas did fine, but the shelling peas tanked, as did the strawberries and raspberries. The broccoli isn’t looking very good and the spinach bolted, but everything else is flourishing. I’ve got a ton of weeds, but who could be out there weeding when it was 85 degrees by 9 a.m.? I’m definitely recording all of this in my garden journal.”

Brooke Davey of Walla Walla was grateful for her mobile garden. “I’m growing squash and strawberries in wheelbarrows,” she said. “I pushed them over to a spot under my large maple so they got morning sun but no sun after about 2 p.m. I also have peppers, cucumbers and basil in old washbasins. I put those in my wagon and pulled them next to the wheelbarrows in the partial shade of the tree. None of those plants showed any signs of stress or burn.”

Sharon Luft, who used to live in Northern California but now resides in Vancouver, Wash., is putting her California experiences to good use. “We are returning to our drought conditioning and following the Brits by collecting rain water this winter to supplement us in the worst heat waves next summer,” she said. “We watered after the sun went down and before sunrise. We had very little loss and some sunburns. We got majority of the berry harvest by using frost cloths.”

Gene Ewert in Kansas practices pre-emptive harvesting. “We harvest produce as soon as things are at even a minimal level for picking to hopefully keep the plants’ stress levels down. We always mulch around them, too.”

Janice Harris Impson, who lives in Louisiana, has a lot of experience with high temperatures. “Mulching is a big key to gardening in the South. My plants always bounce back after a heat wave and start producing again. They may stop if it heats up again but will start back each time it cools down until there are continuous days of heat. Then they won’t produce enough to bother with gathering.”

When Connecticut gardener John Mezzacappa read one of my social media posts about how our corn patch was struggling, he shared an interesting observation: “If you planted corn typical of what is grown in the Midwest, you will be fine. If you planted a variety more commonly grown in New England, you are unlikely to get a corn harvest.”

Carol Nichols intends to think ahead when ordering seeds for next year’s garden. “I’m going to look for varieties of tomatoes and beans, etc., that are more heat tolerant. I’m afraid this extreme hot weather may become the new normal.”

Susan Mulvihill is author of “The Vegetable Garden Pest Handbook.” She can be reached at susan@susansinthegarden.com. Watch this week’s “Everyone Can Grow a Garden” video at youtube.com/susansinthegarden.