Climate-Conscious Gardening
Join Master Gardeners in the Arlington/Alexandria unit of Virginia Cooperative Extension in a series of monthly articles in 2021 as we explore the topic of climate change and practical actions individuals can take in their home landscapes in response.
By Elaine Mills, Extension Master Gardener
Scientists indicate that there are two types of actions home gardeners can take in the face of climate change: adaptation and mitigation. With the first strategy, people make adjustments to actual and expected changes to reduce their gardens’ vulnerability. Adaptive practices to address issues relating to soil, water, plant selection, invasive plants, and pests will be covered in the coming months, while this article will address mitigation with suggestions for science-based techniques individuals can implement to directly reduce the sources of greenhouse gas emissions and slow the pace of further climate change.
Use less gas
One critical change that homeowners can make is to switch from using gasoline-powered machines to electric or, preferably, human-powered tools. Mowing lawns uses 800 million gallons of gas per year and results in accidental spills of 17 million gallons, more than all of the oil spilled by the Exxon Valdez in the Gulf of Alaska. Trading in gas lawn mowers, weed whackers, and leaf blowers for push mowers, hand clippers, brooms, or rakes will reduce the emission of greenhouse gases and pollutants from the burning of fossil fuels.
Compost!
Composting organic yard waste is another important step in the reduction of greenhouse gases. Doing your own composting or sending yard waste along with food waste to city or county facilities prevents the generation of methane that builds up when these materials decompose in oxygen-poor landfills. For tips on making your own “black gold,” see the following public education class recordings:
- Compost: What is it and What’s it to you?: The Art of Composting
- Composting and No Till Gardening: Create a Garden That Thrives
- Leave the Leaves and Other Beneficial Practices
Both Arlington County and Alexandria have food scrap drop off programs:
- Arlington County Composting
- Arlington County Food Scraps Collection
- City of Alexandria Food Waste Composting Stations
Use energy-efficient outdoor lighting
Choosing energy-efficient products and reducing energy consumption for the yard will also reduce carbon pollution. For example, entomologist Doug Tallamy recommends switching from inefficient standard outdoor light bulbs to longer lasting, more energy-efficient LED bulbs.
Yellow is preferred over white to prevent the accidental death of desirable night-flying insects, such as moths. Installing automatic light timers can reduce the energy costs of lights that burn all night as well as protecting the nocturnal migration and nesting of birds from light pollution.
Purchasing solar-powered garden products reduces the carbon footprint even further. (See the website for the International Dark-Sky Association for more details on reducing energy waste and the light pollution that negatively affects wildlife.)
Reduce use of chemicals
Serious reduction of chemicals in the garden—pesticides, herbicides, and fertilizers—is a fourth step toward sustainability. Not only are many pesticides petroleum-based, but their indiscriminate use affects a wide variety of beneficial insects, including pollinators and natural predators, such as parasitic wasps, that play critical roles in the garden ecosystem. Similarly, use of herbicides can cause unintended damage to non-target plants through spray drift. The movement of these chemicals from the land into surface water and groundwater due to runoff of stormwater and leaching can also affect the soil microbiome and, potentially, animals and humans.
Virginia Cooperative Extension (VCE) advises that chemical control should be the last resort for weed, disease, and pest management in a home garden. The efficient use of manual, mechanical, cultural, and biological controls, such as the encouragement of beneficial insects; hand removal of pests; use of beneficial microbes; and proper spacing, pruning, and mulching of plants can be effective means of handling unwanted species. (See VCE’s Pest Management Guide to learn about beneficial predatory insects [pp.2-3 to 2-4] and alternative approaches to caring for vegetable, fruit, and ornamental plants. The MGNV website has a series of helpful articles on controlling mosquitoes and ticks and other garden pests without pesticides.)
Fertilizers, a third category of chemicals frequently used in home landscapes, also have a large carbon footprint. Synthetic nitrogen fertilizers such as urea and ammonium nitrate are very energy-intensive to produce, requiring the heating of natural gas to high temperatures. When added to the energy expenditure for transportation, 4 to 6 tons of CO2 are emitted for every ton of fertilizer manufactured. In addition, all fertilizers, including manure and other organic sources, give off nitrous oxide, a potent greenhouse gas, as they degrade in soils. Additional problems with fertilizer use will be discussed in the upcoming article on building soil health.
Avoid using peat mulch
Two less obvious sources of greenhouse gases associated with gardening are some potting mixes and the pots in which plants are sold. Environmentalists are now urging gardeners to avoid peat-based potting mixes. Peatlands, such as the Arctic tundra, are a huge “carbon sink,” storing 1/3 of the world’s soil carbon. Harvesting not only releases stored carbon dioxide, but also destroys layers that took hundreds of years to develop. Locally sourced compost, leaf much, and pine bark are the most sustainable substitutes for peat.
Reuse plastic pots
Recently, attention has been drawn to the unsustainability of the use of petroleum-based plastic pots by the horticulture industry. Of the 35 million tons of pots generated in 2018, only 8.5% were recycled. Challenges to recycling include the fact that used pots need to be cleaned, they are made of a variety of resins whose codes are difficult to read, and there is no demand in the marketplace for the recycled material. Research is being conducted into creating “plantable” or compostable pots or those composed of bioplastics. Until these alternatives become more widely available, home gardeners can minimize the impact of plastic waste on the environment by reusing larger pots for weeding and transporting material, donating pots to garden clubs for their plant sales, returning pots to small local native plant nurseries, and purchasing small trees, shrubs, and perennials as bare-root plants.
Choose construction materials wisely
Finally, gardeners can reduce their carbon footprint by making wise choices about products they use in construction projects and maintenance. Utilizing existing and salvaged materials, such as bricks and stone, will eliminate the need for manufacturing and transporting new products. Using planter boxes, compost bins, and hoses with recycled content will also be more eco-friendly.
A number of the adaptive actions to be discussed in the coming months will also help homeowners move their gardens closer to a carbon-neutral state. Please return on Wednesday, March 3, 2021 to read about the first of these strategies, Building Your Soil.
Resources
- The Climate Conscious Gardener, Brooklyn Botanic Garden, 2010.
- “The Climate-Friendly Gardener,” Union of Concerned Scientists
- “Gardening for Climate Change,” The National Wildlife Federation
- “Gardening in a Warming World,” Cornell Climate Smart Solutions Program
- “Gardening Sustainably in a Changing Climate,” David Wolfe in The New American Landscape, 2011.
- “Impacts of Chemical Methods,” U. S. Fish & Wildlife Service
- “Plastic Pots and the Green Industry,” Association of Professional Landscape Designers
- “Responding to Climate Change,” NASA