WASHINGTON (April 5, 2010) – What’s the best way to celebrate April, the National Gardening Association’s national garden month?

Plant a garden!

And what’s the best way to plant a garden?

Follow the recommendations in the Union of Concerned Scientists’ (UCS) climate-friendly gardening guide, which is chock full of techniques and tools to help home gardeners turn their gardens into carbon ‘sinks’ that actually absorb global warming pollution.

“Most Americans now know that driving our cars and running our electronic gadgets overloads the atmosphere with global warming emissions, but few realize their gardens can be part of the solution,” said Karen Perry Stillerman, a senior analyst with the UCS Food and Environment Program. “With the right practices, farmers and gardeners can transform their fields, lawns, and gardens so that they store carbon, cut overall emissions, and protect the planet.”

Years of burning fossil fuels and destroying tropical forests has released carbon dioxide and other global warming gases, including methane and nitrous oxide, into the atmosphere, where they act like a blanket, trapping heat and altering weather patterns around the world, Stillerman explained. We already are seeing the effects of climate change worldwide, and unchecked, these emissions will have serious consequences for public health and the environment.

“The Climate-Friendly Gardener: A Guide to Combating Global Warming from the Ground Up” offers five main recommendations for climate-savvy gardeners.

1. Minimize carbon-emitting tools and products: Gasoline-powered lawn mowers and leaf blowers are obvious sources of heat-trapping carbon dioxide. A typical mower emits 20 pounds of carbon dioxide per gallon. Synthetic fertilizers and pesticides, which require a lot of energy to produce, also contribute to climate change. UCS’s guide provides several tips for avoiding garden chemicals and fossil-fuel-powered equipment.

2. Use cover crops: Bare off-season gardens are vulnerable to erosion, weed infestation and carbon loss. Seeding grasses, cereal grains or legumes in the fall builds up the soil, reduces the need for energy-intensive chemical fertilizers and pesticides, and maximizes carbon storage. The guide recommends that gardeners plant peas, beans, clovers, rye or winter wheat as cover crops and explains the specific advantages that legume and non-legume cover crop choices have for gardens.

3. Plant trees and shrubs strategically: Planting and maintaining one or more trees or large shrubs is an excellent way to remove more heat-trapping carbon dioxide from the atmosphere over a long period of time. A multicity study estimated that the trees in U.S. urban areas store nearly 23 million tons of carbon in their tissues every year. That’s more than all of the homes, cars and industrial facilities in Los Angeles County emit annually, or about as much as all of the homes in Illinois or Pennsylvania emit every year. Well-placed trees also shade buildings from the summer sun or buffer them from cold winter winds, reducing the need for—and cost of—air conditioning and heating. UCS’s guide names some suitable types of trees for a climate-friendly yard.

4. Expand recycling to your garden: Yard trimmings and food waste account for nearly 25 percent of U.S. landfill waste, and the methane gas released as the waste breaks down represents 3 to 4 percent of all human-generated heat-trapping gases. Studies indicate that well-managed composted waste has a smaller climate impact than landfills. The UCS guide describes how to create a climate-friendly compost pile.

5. Be smart about your lawn: Residential lawns, parks, golf courses and athletic fields are estimated to cover more than 40 million acres—about as much as all the farmland in Illinois and Indiana combined. A growing body of research (for example, this study) suggests that lawns can capture and store significant amounts of carbon dioxide, but some newer studies (such as this one) warn of the potential for well-watered and fertilized lawns to generate heat-trapping nitrous oxide. The new UCS guide summarizes the science and offers tips for homeowners to make their lawns truly “green.”

“Gardening practices alone won’t solve climate change, but like installing super-efficient light bulbs and using reusable bags, they can move us in the right direction,” said Stillerman. “Seventy percent of Americans have a garden, and each one can make a difference.”

The Union of Concerned Scientists is the leading U.S. science-based nonprofit organization working for a healthy environment and a safer world. Founded in 1969, UCS is headquartered in Cambridge, Massachusetts, and also has offices in Berkeley, Chicago and Washington, D.C.