A row of interconnected rain ‘barrels’ (recycled plastic garbage cans). The barrels are elevated in a ‘step’ sequence, and the simple pipe connections capture roof run-off from a significant rainfall. A screen over the barrel under the downspout filters out debris and keeps mosquitoes out. Photo: Anne Maxwell, MG, Kingston ON.
By Darlene Belton, Master Gardener
My backyard garden is coming into its fourth summer of drought, drained by a row of 18 voracious 50-foot high spruce trees just over the fence in a neighbour’s yard. I’ve lost all my beautiful Annabelle hydrangeas and, even with plentiful directed watering, most plants are just surviving. Your garden may not be as badly affected by the past three low-precipitation summers, but signs are not good going into summer, 2021.
Drought is an age-old part of this prairie region’s climate cycle, but as we are all learning, climate change is exacerbating the threat of severe droughts and cataclysmic weather events. How can we make our gardens more resilient?
This question impelled me through the winter to learn as much as I could about climate change in the prairies and garden resiliency. The question is not an idle one – our very survival could depend on finding effective solutions at both the garden and regional levels. My research included the role of healthy soil biology in the water cycle and helped me compile a list of drought-proofing strategies to apply this summer.
The Canadian government, through Environment and Climate Change Canada, is taking anthropogenic climate change in the Prairies very seriously. In January 2021 it supported the establishment of Climate West to be based in Winnipeg. Climate West is to provide accessible tailored regional climate change information and strategies. Environment and Climate Change Canada and Natural Resources Canada also funded the study, Canada in a Changing Climate, that last fall produced the Prairies Regional Perspectives Report(1), the first in a series. This report notes that “the Prairies … have the strongest warming to date across southern Canada”. “Recent extreme weather events in the Prairie provinces – including flooding, drought and wildfire – have been the costliest natural disasters in Canadian history…” and “are getting worse”. “Ultimately, water shortages would be the most damaging…” “Evaporation and transpiration will increase with warmer temperatures, leading to more frequent and intense droughts and soil moisture deficits over the southern Prairies during summer.” The persistent smoky haze from wildfires that has occurred in recent summers is a destructive accompaniment to drought that, besides impacting human health, also reduces the sun’s intensity, slowing growth in vegetable gardens.
Recent weather patterns are also disturbing. Winnipeg had its driest year on record in 2020 (2) , and most of southern Manitoba saw less than 50% of average precipitation from December to March 2021(3). This is of concern because this region relies heavily on early spring snowmelt to prepare the ground for growth. However, the drought is not uniform across the region. On June 28, 2020, Brandon and area saw 155 mm of rain in 10 hours, nearly double the monthly average and 30% of its total precipitation that year , much of which ran off, taking precious topsoil with it. Even this year’s mid-April snowstorm will have little ameliorating effect as, for example, the 20-25 cm that fell in Winnipeg equates to only 25 mm of rainwater(4), – the amount a vegetable garden needs each week in the growing season, – and a hot, dry summer is forecast.
North Dakota farmer and regenerative agriculturalist, Gabe Brown, cites the success he has had in building soil porosity through techniques such as limiting mechanical and chemical disturbance, plant diversity, and continuous soil cover – organic mulches and green manure – which allow diverse soil biology from bacteria to vertebrates, to thrive. Within the complex soil food web, soil life-forms partner with plant roots to cycle nutrients in a process that also creates aggregated soil. The gaps and passageways in aggregated soil readily absorb and hold water, like a sponge, allowing the land to get maximum intake from rain, even torrential downpours, thereby reducing or eliminating run-off. Comparing his land to a neighbour’s who tills and plants monocultures, Gabe notes that in a recent downpour the neighbour’s land could absorb only a half inch/hour in comparison to his, that, after 10 years of regenerative practices, absorbed 30+ inches/hour. It is possible to plunge a stick with ease two feet deep into the soil on Gabe’s farm(5).
(1)Sponsored by Natural Resources Canada; authored by the Prairie Adaptation Research Collaborative (PARC): Climate Research Centre, University of Regina. Quotes: p.8, pp. 19-20.
(2)Weather Network, “Winnipeg experienced its driest year on record in 2020”. January 3, 2021.
9#0Weather Network. “Digging into the drought: Why one massive Prairie rainstorm doesn’t help.” March 5, 2021.
(4)Snowfall to rainwater calculator. National Weather Service.www.csgnetwork.com
Obviously Gabe has found ways to increase the productivity and resiliency of his 5,000 acre property in a climate, geography and ecology similar to ours. What can we as gardeners do to try to match this success on a much smaller scale?
Well aggregated soil. Note the large aggregates that create passageways for water and air so the soil can absorb and hold water like a sponge. Photo: Darlene Belton, MG, May 2020.
Ideas to increase your garden’s drought resiliency, now and into a hotter, drier future:
1. Identify your starting point – compaction issues. How quickly do puddles sink in after a rain? How easily can you push a spade into the ground? Does a spade full of soil reveal large aggregates? Are there five or more earthworms? If you put a clump of soil in a glass of water, does it hold its shape or break up quickly? Poor results indicate high compaction and deficient healthy soil life(6).
2. Stop roto-tilling and excessive transplanting. Every time you dig into the soil you kill myriads of microbes and destroy fungal networks, all of which support your plants’ health and growth, and in fact, create the ‘soil sponge’ that allows your soil to retain water to withstand drought. If your soil is badly compacted, a one-time hand-spade turning followed by applications of compost can start a recovery process, with occasional broad forking to loosen soil in subsequent years. Take great care with any digging to avoid damaging perennial, shrub and tree roots.
3. Cover the soil. Bare soil dries out, killing soil life near the surface, and its structure is damaged by the force of raindrops when it does rain (remember the Chinese water torture!), not to mention topsoil run-off. Applying compost covered with mulch feeds soil microbes and protects against desiccation.
4. Plant selection. For ornamental gardens, investigate plant origins and select cultivars and species plants with dryland origins (i.e., Mediterranean, California) – as long as they are also hardy for our climate zones – and give serious consideration to our native prairie species and cultivars. Select trees and shrubs with the same criteria. Trees with deeper roots can withstand drought better after they are established. Plants with gray foliage, leaf hairs or glossy, small or succulent leaves fare better in drought. Decide how many ‘water hogs’ you are willing to invest the extra cost and effort to support in droughty periods and ensure they are placed near supplemental water sources. Early maturing vegetable varieties will still produce by fall even if wildfire smoke weakens the summer sun.
5. Irrigation. The quality of vegetable harvests is badly impacted by drought – leading to tough, bitter roots and fruits with a mealy texture(7) . Raised beds with wide rows and staggered, appropriately placed interspecies plantings hold more plants than traditional rows. The various plants’ different root lengths result in “a more even distribution of soil moisture”(8) . Water from a hose directed to the root zones of individual plants is advised, though time-consuming. Soaker hoses and drip irrigation lines can be set up relatively permanently in appropriate configurations (and covered with mulch) to direct water to desired plants and ‘starve out’ weeds. Soil moisture meters and rain gauges help determine how much irrigation is needed per week so only gap-watering is done. A row of interconnected rain barrels can capture the massive roof run-off during infrequent downpours to be held for drought’s return. Find ways to slow the run-off of rainwater during downpours, so it can pool on your property and sink slowly into the earth.
6. Managing lawns for drought. Though many gardeners are reducing the size of their lawns these days, most of us want to retain at least some lawn, for recreation space or pathways. Traditional Kentucky turf grass is a ‘water hog’. Fescue mixes and some low-growing native grasses are suitable replacements which tolerate drought well. However, remember that if trees abut your lawn, their roots often lie just under the turf. It may be worth doing supplemental watering, not so much for the lawn as for the trees that must stay hydrated to withstand attacks from invasive pests and other diseases.
(5)“Applying the 6 Principles of Regenerative Ag.” Gabe Brown, presentation at the Soil Regen Summit 2021, March 16, 2021, sponsored by The Soil Food Web.
(6)Preparing the Ground for Healthy Soil: “Soil Structure”. Webinar 2. Compost Council of Canada. April 14, 2021.
(7)The Weather-Resilient Garden: A defensive approach to planning & landscaping. Charles W.G. Smith. Storey Publishing: 2004. Page 157.