Gardening in the Age of Climate Change
It used to be that gardeners never had to consider much beyond their own tastes and whether their chosen plants would grow where they put them. Now it’s not just that the times are changing; the climate is too. All sorts of new considerations impact the gardener, and in turn the impact of backyard gardens has mushroomed in importance. Does the garden conserve water and enrich the soil? Does it offer habitat protection to living things? Could it store more carbon or produce more food? Do changes in frost dates change what it will produce?
Your backyard garden can benefit from the insights of recent science. While living things used to be studied mostly as individuals or species growing separately, ecological thinking sees the relationships of living things to each other and to the environmental conditions that surround them. Living things constantly influence each other and their surroundings. Aspects of gardening that used to be seen as inanimate, like the soil, are now known to be teeming with life. Garden practices that used to be routine, like applying fertilizer or insecticides, are now viewed through their impact on the environment and collateral damage on non-target species. The role of backyard gardens in preserving habitat corridors for threatened species of birds, bees, and butterflies, once incidental, is now essential.
The UC Master Gardeners of Sonoma County wants to help you keep abreast of these changes and make your garden earth-friendly. So we have compiled a list of quick suggestions for gardening in a time of climate change and habitat destruction. We believe you want to make your garden part of the healing of the planet. Together, we can all make small changes that add up to a lot.
Use ECO system thinking. Observe the connections between all living things and between living and non-living things. Nothing stands in isolation.
Approach climate change through mitigation and adaptation. Gardeners that cut down on the need for gas-powered garden tools and fossil fel-based fertilizers are mitigating the causes of climate change by reducing greenhouse gas emissions.
Grow plants. Maintaining healthy living plants serves to sequester carbon that would otherwise be in the atmosphere as CO2 gas.
Use regenerative garden practices. No till gardening, composting, and good plant selection are some of the practices that enhance ecosystems, enrich soils, and improve watersheds.
Conserve water in your landscape. Irrigate efficiently. Consider replacing sprinklers with drip irrigation. Plants’ highest water needs are during May through July, due to growth and long days. Beginning in August, plants’ water needs decrease as day length decreases. Incorporate “seasonal setbacks” into your irrigation program, gradually decreasing the amount of irrigation per month, whether you water manually, with a digital hosebib timer or with an automated controller and valves.
Hydrozone. Group plants with similar water needs (plant factor) and microclimate together (high, moderate, low or very low water use). Besides the plant factor, take into account root depth, microclimate (sun, shade, wind, heat), slope and elevation, and soil type. Water each hydrozone with a separate valve if you have an automated irrigation controller, or from separate hosebibs. If you have a single area with multiple water needs you need to water to the level of the plants with the highest water needs. By hydrozoning you are able to increase the efficiency of water use in your landscape.
Plant low water use plants to conserve water. Low water use plants use about one-quarter the amount of water that high water use plants need. We have a Mediterranean climate, with dry summers and warm, wet winters. Choose Mediterranean plants and California natives, which are well-suited to our climate.
Keep water on your property. “Slow it, spread it, sink it, store it.” Use a variety of ways to keep water on your property, prevent erosion and recharge the underlying aquifer. Use permeable hardscape, such as flagstones and decomposed granite. Rainwater percolates down to the roots of your plants where it is needed rather than running off, taking your topsoil with it. Berms (mounds) and swales (valleys) and raingardens in your landscape slow and spread rainwater, giving the water time to infiltrate into the soil. Consider harvesting rainwater with tanks or barrels.
Plant shade trees to reduce energy. You can significantly reduce indoor energy use by strategic placement of trees. Trees can reduce surrounding air temperatures by 9° to 12°F. Deciduous trees (trees that lose their leaves each winter) offer one of the best opportunities to reduce home cooling costs and energy use. Planting them on the northeast-to-southeast and northwest-to-southwest sides of your house provides excellent protection from the summer sun by shading the roof, walls, and windows. Deciduous trees permit winter sunlight to warm the house. This is why it is best to avoid planting deciduous trees on the south side of your house if you live in a cool climate. In the winter, even bare branches of mature deciduous trees can reduce the amount of sun reaching your home. For information on firewise tree placement in your home landscape, refer to our web page for more information: http://sonomamg.ucanr.edu/Firewise_Landscaping/Defensible_Space/.
Plant cover crops. Vegetation prevents erosion, keeps carbon dioxide in the soil, maintains the soil structure, feeds the soil and keeps water in the soil rather than running off. Leguminous cover crops are a cheap source nitrogen for the soil, which will be ready for your vegetable garden in the spring.
Incorporate organic matter (compost, mulch) into your garden. Feed your soil, which will feed your plants. Organic matter and microorganisms in the soil make nutrients available to the roots of plants and keep the nutrients in the root zone. Organic matter improves soil health, creates and maintains good soil structure, retains water and sequesters carbon. Organic mulch prevents erosion, moderates soil temperature, conserves soil moisture and reduces weeds. As mulch decomposes, it becomes compost and feeds the soil.
Eliminate chemical controls (pesticides - insecticides, herbicides, fungicides). Use Integrated Plant Management (IPM) to maintain a healthy environment for your plants. Using insecticides, for example, will kill the beneficial insects as well as the ones we don’t want in our gardens. These toxic chemicals will eventually find their way into our waterways and groundwater. Our instinctive reaction, when faced with a bug or disease killing our favorite plant or a weed strangling our garden, is to reach for the chemicals. This is quick and easy but counterproductive in the long run.
Minimize fertilizer. Organic matter (compost) is all the food our soil needs to support our plants. Nutrients remain in the organic matter and soil until they are needed by plants. Excess fertilizers are easily leached from the soil and end up polluting our rivers and streams. Fertilizers are energetically expensive to manufacture.
Do not till your soil. Add organic matter (compost, mulch) onto the top of your soil. The soil is a complex ecosystem with microorganisms such as fungi and bacteria as well as large organisms including earthworms. This ecosystem works best to feed and support plants and maintain soil structure if it is not disturbed by actions like tilling. The organisms themselves will pull the organic matter into the soil. Disturbed/tilled soil releases carbon dioxide into the atmosphere.
Grow your own food: Grow nutritionally rich, pesticide free, fresh food to decrease CO2 generated by food transportation over long distances and to increase your own and your community's local food security.
Increase the biological and botanical diversity of your food garden: Plant different varieties of the same vegetable. Plant varieties with different growing needs and different days to maturity, different adaptations to cool and hot growing conditions, and different levels of water requirements. Mix in pollinator plants to help feed insects. Consider perennial vegetables, herbs, and fruit trees as part of your food garden.
Stay flexible and adaptable: Keep observing. Try new strategies for growing plants and adapting to changing conditions. Consider using crop protections such as shade cloths, frost covers, hoop houses. Plant smaller amounts of vegetables more often to adapt to variable conditions. Consider planting varieties that are adapted to changed conditions you already observe in your area (for example reduced number of frost days for fruit and nut trees).
Promote habitat gardens by providing food, water, and shelter. Conserve water, but have a water source available for bees, birds, and butterflies. Plant native plants whenever possible; flora and fauna evolved together. Biodiversity creates resilience to stress: plant a variety of plants suitable for the sun and water conditions.
Be a good environmental steward: Eliminate garden tilling. Eliminate chemical fertilizers and pesticides. Use compost, mulch and cover crops to enrich and protect your garden soil. Keep plants growing year round to absorb and sequester CO2 .
Be part of a "growing community": Share food, seeds and plants, as well as information with your neighbors, farmers and friends. Learn from others’ experience and knowledge.
Be a good climate steward through active involvement. Engage friends and neighbors in discussions about climate change. Use reliable sources for information. Track daily weather trends to observe climate changes over time. Become a citizen scientist by sharing data you collect with local or online organizations.
- California Department of Water Resources: https://water.ca.gov/
- California Water Board, State Water Resources Control Board: https://www.waterboards.ca.gov/water_issues/programs/conservation_portal/resources.html
- Cornell Garden-Based Learning, Gardening in a Warming World, 2018: https://gardening.cals.cornell.edu/garden-guidance/gww/
- QWEL (Qualified Water Efficient Landscaper) Reference Manual, Sonoma-Marin Saving Water Partnership, 2018. https://www.qwel.net/files/QWEL_Reference_Manual_SMSWP_INTERACTIVE.pdf
- Reed, Sue and Stibolt, Ginny, Climate-Wise Landscaping, 2018.
- WUCOLS III, A Guide to Estimating Irrigation Water Needs of Landscape Planting in California. 2000. https://cimis.water.ca.gov/Content/PDF/wucols00.pdf
- UCANR Sustainable Landscaping in California: https://anrcatalog.ucanr.edu/pdf/8504.pdf
State of California Department of Water Resources Water Efficient Landscaping: https://water.ca.gov/Water-Basics/Conservation-Tips/Plant-and-Landscape-Guide