Linda's List: Heat & drought lessons

This spring has unfolded remarkably like last spring, both in lack of April rainfall (around 75% below average over the region, again) and the same higher than average temperature regime. Nighttime temperatures have consistently been above average all spring, resulting in flowering and plant development in my garden occurring about a week earlier than last year. We have already had record-breaking warm days in April and a couple of hot days are forecast, starting today. While it might be another challenging year for some vegetables it should be another great year for fruit crops.

At this point the soil is so warm that you can probably plant most things. If we do get a cold night, the warmth in the soil should protect tender plants if you cover them with plastic or floating row cover. I am dithering on when to set out cucumbers, beans, melons, basil, peppers and corn seedlings, but mine are all shortly going to be too big for the trays I started them in so it will force my hand….after years of seeing late frosts occur in May, it just give me the willies to plant too early! That said, I have 4 zucchini fruit (from ‘Partenon’ parthenocarpic zuccs; William Dam Seeds) ready to pick in a week or so from plants that have been out in the garden for a month. And Emily W. just sent lovely photos of hers picked May 2nd from her Quadra Island glass house in a spot “known for its cold microclimate”.

In no particular order, here are some lessons I learned from last year’s long hot, dry summer:

- Be extra vigilant in staying on top of watering and shading seed beds and young plants. While anything can be used to temporarily shade plants, I am really enjoying having lengths of horticultural shade cloth I can leave in place for several hot days in a row because it lets in enough light to allow growth. I have already had to deploy all of my cooling tools this spring, including shade cloth over beds of seedlings, burlap covers to cool seedbeds for germination and early mulches around young plants. Lawn clippings are excellent for this because they are soft and fine enough to sprinkle around tiny plants. Old leaf mulch from last year is also easy to crumble into a fine grained mulch.

-Be ready to start regular irrigation, probably quite soon for some gardens, depending on soil and drainage. Last year many of us were caught unaware of how dry the soil had become in May with the result that early plantings and strawberries harvests suffered. Ample soil moisture is critical for all plants during from germination and transplanting until roots are well established. Leafy greens, corn, celery, celeriac, endive and onion family plants continue to need regular water throughout the season. Cabbage, broccoli and cauliflower also need more water while heads are developing. For fruiting crops (e.g., tomatoes, squash, etc.) attention to irrigation is important during flower and fruit development. Well established tomatoes with deep roots in deep soil can manage on less water later in the summer, but don’t stint on watering young plants, plants in pots or in gardens with shallow soil (allowing the soil to dry out, even intermittently, is the main cause of blossom end rot and plays a role in other ripening disorders).

-Do a better job of checking soil moisture to judge watering needs. Watering infrequently and deeply makes roots go deeper in the soil. If, or when, your water district restricts outdoor watering, deep rooted plant handle it better than shallow-rooted plants. Of course, don’t forget to put on a thick mulch of leaves, straw or other organic material as soon as possible.

-No more tomatoes and peppers in my greenhouse! I just can’t keep it cool enough to avoid having the flower pollen sterilized by the heat. My greenhouse is being given over to the various orange, purple and white sweet potatoes (“yams”), who will thoroughly enjoy the scorching heat.

-Adjust planting schedules. Gardeners who had to keep their gardens short of water last summer found that Swiss chards and kales performed well anyway. I usually sow a small bed of these crops in the spring for summer use followed by a larger planting in July to provide enough greens for winter harvests. This year, I planted enough chard and kale for the whole year last week so the plants would have deep roots by midsummer and there would be fewer tiny seedlings to baby along in July. Depending on how the season unfolds, I will probably delay sowing dates for other mid-summer crops that can’t be sown early because they bolt (e.g., winter lettuce, spinach, mustard spinach) by about a week and will keep them under shade cloth. It worked so well last summer that I will again sow a second crop of summer squash in the third week of June. With that timing I had young, vigorous plants able to resist powdery mildew infections in the late summer. They were astonishingly healthy compared to older squash plants and produced well late into the year (last zucchini pick Nov. 13!).

-Try more heat adapted lettuce: Lettuce is grown in hot climates so I am looking for varieties specifically described as heat or hot weather tolerant. For example, I have found ‘Jericho’, a romaine lettuce from Israel (Full Circle Seeds) and ‘Anuenue’, a Hawaiian-named crisphead (West Coast Seeds) among others.

About Linda A. Gilkeson, Ph.D.

Salt-Spring---Linda-GilkesonLinda earned a Ph.D. in Entomology from McGill University in 1986, then moved to British Columbia to work for Applied Bio-Nomics Ltd., a company that produces biological controls. From 1991 to 2002 she worked for the provincial government, promoting programs to reduce and eliminate pesticide use. She was head of the provincial State of Environment Reporting Unit for the next six years, then the Executive Director of the Salt Spring Island Conservancy until the end of 2011. Linda now devotes her time to writing, teaching and consulting.

Linda has co-authored pest management training manuals for the government and organic gardening books for Rodale Press. She has self-published two books: Year Around Harvest: Winter Gardening on the Coast and West Coast Gardening: Natural Insect, Weed and Disease Control. Her recent book, Backyard Bounty: The Complete Guide to year-Round Organic Gardening in the Pacific Northwest, has become a BC best seller.

As a private consultant, Linda is a regular instructor in the Master Gardener programs in BC and is busy year around giving workshops on pest management and organic gardening.

Linda has served as President of the Entomological Society of Canada, the Professional Pest Management Association of BC, the Entomological Society of BC and the Salt Spring Island Garden Club. She was awarded a Queen’s Jubilee medal in 2003 and an outstanding achievement award from the Professional Pest Management Association of BC in 2005.

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May 5, 2016 7:52 PM

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