In the pathway: Adapting your garden to a changing climate
Climate resilience
Strategies to adapt the garden to drought, excess water and extremes.
Explanation
Diversify varieties, tier the crops, increase functional shade, store water, enrich the soil with organic matter and choose tolerant species: all levers for staying productive in the face of climate disruption. A central concept of adaptation ecology (Folke et al. 2010, Ecology and Society 15(4):20) applied to the garden by Toby Hemenway, Geoff Lawton and the Transition Towns movement initiated by Rob Hopkins (2006).
Refined definition
Resilience is the capacity of a system to absorb a shock and reorganise while keeping its essential functions. In the permaculture garden, climate resilience combines: (1) DIVERSIFICATION of varieties and species (if one species suffers, another takes over), (2) RESERVES (water, biomass, soil) to buffer the peaks, (3) REDUNDANCY of functions (several plants fulfil the same function), (4) FLEXIBILITY of use (harvesting at several periods, in several forms).
Key points
Adapting to drought
Thick permanent mulch (10-15 cm): an organic mulch covering the whole soil cuts evaporation from its surface by roughly half (FAO Irrigation and Drainage Paper 56). Rustic and old varieties (tomato Olivette de Provence, squash Sucrine du Berry). Increase functional shade with hedges, pergolas, tall sunflowers. Store water (tanks, ponds, swales). Favour drip irrigation or ollas (buried pots), which bring the water to the root instead of wetting the air and the bare soil. Beware of the figure that circulates: savings of 60% and more concern the switch from GRAVITY watering (flooding, furrows) to drip. Compared to sprinkling, the real gain is far more modest, on the order of 5 to 20% in market gardening depending on the type of sprinkler, a bit more in windy regions. Source: Serra-Wittling C. & Molle B. (2017), “Évaluation des économies d'eau à la parcelle réalisables par la modernisation des systèmes d'irrigation”, Irstea/INRAE, UMR G-EAU.
Adapting to excess water
Raised mounds (a draining effect). Moisture-loving plants (comfrey, mint, iris) at the pond's edge. Tolerant plants (cabbage, parsley, chard). Continuous plant cover to avoid erosion. Limiting compaction (no tractor on waterlogged soil). A controlled overflow system (overflow toward a low, uncultivated area).
Adapting to late frosts and extremes
Diversify the flowering periods (early AND late varieties of the same species). Forcing fleeces and mobile tunnels. Planting in differentiated thermal zones (warm south-facing slope, cool north-facing slope). Thermal inertia: water, stone and biomass store heat by day and release it at night. Successive crops: if one is frosted, another grows back quickly.
Watch out for
- • A variety resistant to drought this year may be outclassed by another in 5 years: resilience implies continuous testing, not a dogma.
- • Water stored in the open evaporates a lot in a Mediterranean summer: prefer a covered tank or a deep, partly shaded pond.
Sources
- Folke, C. et al. (2010). Resilience thinking: integrating resilience, adaptability and transformability. Ecology and Society, 15(4), 20.
- Allen, R.G., Pereira, L.S., Raes, D. & Smith, M. (1998). Crop evapotranspiration: guidelines for computing crop water requirements. FAO Irrigation and Drainage Paper 56. Rome : FAO.
- Serra-Wittling, C. & Molle, B. (2017). Évaluation des économies d'eau à la parcelle réalisables par la modernisation des systèmes d'irrigation. Irstea, UMR G-EAU.