This may well turn out to be one of the most important blogs I’ll ever write, and I owe huge gratitude to Linda Gilkeson, renowned food gardener, author, and educator based on Salt Spring Island, BC. Linda held a public webinar in July 2022, parts of which I am summarizing here.
Between June through December of 2021, coastal British Columbia experienced record-setting heat and cold, drought and rain events, all within six months of each other. The now infamously slow spring of 2022 set new records for cold and wet weather.
While the average global temperature is rising, we are not likely to grow bananas in Victoria. Instead, much like the rest of the world, we are seeing increasingly variable, and rapidly fluctuating, local weather patterns with extended periods of previously unknown extremes.
This of course has profound effects both on natural ecosystems and all things agri- and horticulture. Summers on average may get warmer and longer, but on the flip side, this means disruptions in plant growth and bloom cycles, and more generations of some plant-feeding insects. We are also losing growth days to both cold spells and heat waves.
Too much of a good thing — even sunshine — is a bad thing. Sunscald injures leaves and fruit, excess heat causes growth abnormalities and can actually sterilize pollen (for tomatoes, this happens above 32 degrees C). When heat and drought combine, the results are devastating: Plants close their stomata to prevent water loss; as a result, the cooling effect of transpiration ceases, and photosynthesis stops, along with water and nutrient movement between roots and leaves.
Meanwhile, prolonged cold and wet conditions in spring can lead to reduced pollination and crop failure. Low temperatures also inhibit soil biological activity and plant nutrient uptake. Waterlogged soils are tough on microorganisms and plant roots alike; later on, these plants are more vulnerable to drought, and more susceptible to root disease and blowdown.
So how do we adapt, how do we build resilience to keep gardening and especially growing food?
To start with, choose tough, proven, disease-resistant species and varieties; this is not the time to test the limits of hardiness. Plant more perennials, both ornamental and food crops, along with traditional annuals. It helps if they have low summer water requirements. Fruit trees for the future are late flowering and possibly self-fertile.
Grow several different varieties of any one food crop for redundancy; if one type struggles or fails by mid-summer, rip it out and plant something fast maturing in its place (40 to 60 days to harvest). Some veggies are biennial and can be overwintered; they tend to be very successful in their second year.
Learn to save seeds (“Seed Security is Food Security!”), and adapt seeding and planting to the weather. In a cool spring, wait for the soil to warm to 15 degrees C; if it’s very warm in early to mid-summer, sow a little deeper and cover or shade the seed beds. Whenever feasible, plant trees and shrubs in the fall, with the longest possible period before the next drought, and be prepared to give supplemental water during the first couple of summers.
Watch the weather forecast and be ready to step in quickly. In a heat wave, provide shade to the garden during the hottest hours of the day.
You can invest in fancy shade fabric, or improvise with bed sheets, tablecloths, lace curtains, wooden lattice frames, or wicker fence panels. Be sure you can adequately vent and shade the greenhouse or tunnel. Heat kills; shade merely slows down growth.
By contrast, expect colder, longer Arctic outflows in winter. Greenhouses, cold frames and cloches help extend the season or weather sudden cold spells. Stay alert for late spring frosts, and cover tender seedlings with tarps or plastic sheeting if needed. It’s better to lose a few to the reduced light than all of them to a hard frost.
Prepare for heavier rainfalls: If areas of the garden are waterlogged, explore drainage or diversion options. Winter veggies and permanent crops like strawberries are better off in mounded or raised beds. Conversely, experiment with slightly sunken beds for summer growing.
Of course, also plan for drier summers; perhaps consider a low-volume irrigation system. Better yet, find creative ways to capture and use rainwater and household grey water. Invest in self-watering containers if your garden is on the deck, balcony, or rooftop.
This goes hand in hand with year-round mulching, both with cover crops and with traditional mulching materials, especially plant residues (“chop-and-drop” a crop, flower, or weed right where it grew). Remove mulch only briefly in spring to allow seed beds to dry and warm up. Stockpile dry leaves in the autumn for use the following summer.
Keep building soil biology and organic matter content. As much as possible, minimize soil disturbance. With intermittent “feast and famine” cycles of precipitation, our greatest water (and nutrient) storage system — even more than rain barrels and cisterns — is the living, breathing, well-structured soil.
Storm and wind proof the garden by removing vines off trees (vines increase wind sail and snow load), pruning climbers hard in the fall, and providing sturdy permanent plant supports. Also consider adding structural elements such as hedges, windbreaks, walls and fences to create smaller, more sheltered garden rooms. But remember, food gardens need at least six to eight hours of full sun every day.
Above all, plant more plants: Trees to capture and store carbon above ground and below; climbers and ground covers for multi-storey landscapes; more native plants best adapted to local conditions. Make a generous allowance for a diverse range of wildflowers and even weedy volunteers (how about replacing some of that lawn…?) to support the all-important wild pollinators. Finally, have some fun going all out and planting more densely than you ever thought possible. And remember to share your success stories with other gardeners!
Here’s Linda’s entire presentation with pictures and more details: