New frontiers sprout in ‘green' gardening

Green gardening isn’t just about compost bins and rain barrels anymore. The ecologically aware can select native plants, analyze their soil, and take steps to protect local fish populations.

“We have a whole program on salmon-safe gardening here,” says Sarah Hayden Reichard, professor of conservation biology at the University of Washington and author of “The Conscientious Gardener: Cultivating a Garden Ethic” (University of California Press).

Phosphorus from garden fertilizers sinks into the soil and eventually flows out into waterways, causing excess plant growth, which eventually leads to depletion of oxygen in the water, she says.

“It’s an interconnected world, and when you do something in one place, it affects things in other places, in ways that we can barely imagine,” says Reichard.

She offers fresh ideas for green gardeners:

Pick the right plants: Native plants are great if you want to support local wildlife and give your yard an authentic sense of place but, Reichard cautions, some can be major water hogs and others may prove to be invasive. Just because a plant is native to your broad region, it doesn’t necessarily mean it’s native to the precise area where you live.

Gardeners can find good information on plants, native and invasive, at local botanic gardens and arboretums, as well as from local conservation groups.

Respect your soil: It isn’t always easy to love the soil you’ve got, but you’ll save resources and reduce waste. Accept that you may not be able to grow certain plants in wet or clay soils, and don’t feel that you’ve got to pump your soil up with large amounts of organic matter.

“You (generally) need 10 percent or less organic components — people think you need much more,” she says.

Go easy on fertilizer: “Fertilizers are among the worst polluting culprits — and it does not matter if they are from organic or synthetic sources,” she writes.

The elements nitrogen and phosphorus are good for garden plants, but they’re bad for fresh water, she writes. She suggests fertilizing most woody plants and herbaceous perennials sparingly. Mulching with well-aged manure, compost or other easily broken-down materials is sufficient.

Reichard uses fertilizer on her vegetables, roses and containers, but not on her lawn and shrubs. In the fall, she rakes leaves into beds and lets them decay over the winter.

Use less water: “Water is a finite resource, and as the human population grows, we have less of it to go around,” Reichard says.

She suggests choosing plants that don’t require much water, reducing your lawn area and putting water-hogging plants only in areas that are naturally wet. You also can group plants with the same water needs, minimizing waste.

“It is generally best for plants if you water deeply and less often: usually about an inch of water, including precipitation, each week is enough,” she writes.

Try peat moss alternatives: Peat moss holds moisture well and it’s popular among gardeners. Unfortunately, it’s harvested by draining and destroying peat bogs, some of which are centuries old, and that’s cause for concern, says Reichard. Many scientists believe that peat bogs, which hold vast amounts of carbon, can help prevent global warming.

Reichard suggests some peat alternatives, among them:

Coco peat, coir and coir dust, which are made from coconut fibers and offer peat-comparable water absorption and drainage. Buy coir labeled for horticultural use to avoid high salinity.

Compost, or decomposing organic matter (often leaves, grass, manure, bark or nutshells). Compost offers water absorption similar to peat’s and is generally higher in nutrients such as nitrogen.