DETROIT — Since long before the phrases “carbon footprint” and “global warming” went mainstream, many veteran gardeners have been quietly pursuing their hobby under a few guiding principles:

Be thrifty. Be frugal. Don’t waste resources or cash.

Much can be learned from those experienced gardeners, and a wider audience is likely ready to pay attention.

Americans spent an average of $48 on vegetable gardening and $350 on landscaping, according to the National Gardening Association.

With disposable income shrinking for activities like gardening, anything that saves even a couple of bucks and ranks as green will be popular.

At the same time, concern about pesticide use is rising, and people are becoming more interested in buying fruits and vegetables that are grown locally, according to Gary Heilig, a horticulture educator.

When Heilig teaches classes, he says, more people seem to be interested in trying vegetable gardening, even if it’s on a small scale, like growing tomatoes in containers on the deck or patio.

“I’m encouraging people to do more local producing of their own food and limit what you put on it,” he says.

So here are some ideas for gardening greener from Heilig and others who have been digging and planting for years.

Gary Heilig

Job: Horticulture educator, MSU Extension in Ingham County

Gardens in: Eaton Rapids, Mich.

Gardening for: 40 years.

Heilig starts many plants from seed. In addition to buying seeds, he collects them from perennials and trees. Those who collect and save seeds “may have to do research on how to get them started but it can be worth it,” Heilig says. Saving seeds to start more plants will work as long as the plants aren’t hybrids.

Like many experienced gardeners, Heilig is an enthusiastic composter. He collects healthy garden clippings and mixes them with materials like fallen leaves. Eventually, the pile turns into a rich soil amendment.

“I try not to send organic matter off my property,” Heilig says. “I try to bring materials in and recycle what’s there. Over time, it can really build up your soil. “It also saves $3 or more per bag that might otherwise go to buy commercially produced soil amendments like peat or compost. For more about composting, go to cwmi.css.cornell.edu/ compostbrochure.pdf

Norm Lownds

Job: curator, Michigan 4-H Children’s Garden; MSU associate professor

Gardens in: East Lansing, Mich.

Gardening for: 45 years.

For starting seeds, Lownds recommends reusing salad and other food containers that have clear plastic tops. Punch a few holes in the bottom half so water will be able to drain out. Fill the container with potting soil, add seeds, water, then put the cover back on and you have a mini-greenhouse. The containers can be reused for years and then turned in for recycling, he says.

Fran Knorr

Job: Cranbrook Gardens volunteer; retired teacher

Gardens in: Beverly Hills, Mich.

Gardening for: 60 years.

During the growing season, Knorr shreds paper and uses it for mulch. She applies a thick layer around plants like street trees. To make the area more attractive, she spreads a thick layer of cut up leaves or shredded bark on top.

Dean Krauskopf

Job: Extension educator in the southeast Michigan region, MSU Extension, and host of a radio gardening program.

Gardens in: Novi, Mich.

Gardening for: 55 years.

Krauskopf is a big fan of organic mulches to conserve soil moisture and minimize weed germination, because “weeding is not high on my list” of preferred activities, he says. “Some of the best mulch I’ve had in my life was nothing more than leaves I piled up and ran through a mower. Boy, that was great,” he says. In fact, he says, he once turned pure sand into rich, black soil within a few years by working in 4 inches of shredded leaves each year and putting a few more inches of shredded leaves on top. Usually, Krauskopf keeps the top layer of mulch no more than 2 inches deep. That discourages plants from rooting in the mulch and allows the soil to dry out enough that slugs aren’t a problem.

Ashley Atkinson

Job: Director, urban agriculture, Greening of Detroit

Gardens in: Detroit.

Gardening for: 11 years.

Atkinson boosts her garden’s output by stretching the growing season. She plants cold-tolerant crops in early spring and then again in late summer for a second harvest in the fall. To protect plants, she recycles household materials (old sheets, empty milk jugs) to cover plants when chilly night temperatures threaten them. “The techniques are really low-cost and easy to learn but they require being really in tune with what’s happening outside and in your garden,” Atkinson writes in an e-mail. The Detroit Garden Resource program’s Keep Detroit Growing series offers classes on how to lengthen the growing season from six to eight or more months. For more, go to www.detroitagriculture.org/ garden_resource_program. htm.GOING GREENER THIS YEAR

1. Ask nurseries and garden centers to recycle plastic pots, flats and containers, and frequent those that do. For example, Telly’s Nursery in Troy, Mich., accepts pots and trays, and starting this season is growing herb and vegetable seedlings in biodegradable pots. And Eckert’s Greenhouse in Sterling Heights, Mich., announced this month that it will plant most of its annual and perennial plants in recyclable biodegradable containers this year. Any skeptics should take a look at the Missouri Botanical Garden’s program, which collected more than 100,000 pounds of pots, cell packs and trays in 2007 alone ( www.mobot.org/hort/activ/plasticpots.shtml). Steven Cline, who runs the program, says similar efforts are in the works in Minnesota, through the state landscape and nursery association, and at the Morton Arboretum near Chicago.

2. Plant a shade tree on the west or south side of the house to keep the house cooler in summer.

3. Reconsider plant choice and placement. Group moisture-loving plants in a low area or where they’re easy to reach with the hose. Or, if you don’t have money to burn on the water bill, select plants that require less frequent watering.

4. Share plants and cuttings with friends, and go to plant exchanges.

5. Apply a layer of organic mulch in beds and around trees and shrubs after the soil warms to conserve soil moisture and discourage weed seed germination.

6. Buy local. The “locavore” movement is gaining ground among foodies. How about becoming a “locaculturist,” giving an edge to locally grown plants? Find them at nurseries, garden centers and farm markets. Buying local also supports the economy.

7. Grow vegetables. A few containers of greens or herbs boost flavors and freshness, and they’re so convenient you are more likely to use them more frequently than if you had to buy them at the store.

8. Keep a washable blanket or tarp in the car so you won’t need another plastic sheet every time you get a load of something gritty at the nursery. Carry a reusable cloth or mesh bag, too.

9. Use a rain barrel to collect water for use in watering garden plants.