If you're tackling organic vegetable gardening for the first time, here are a few tips to get you started. They're from organic gardeners and gardening experts around Tucson.

Get rid of your old soil. If you've used chemical fertilizers the last few years, your soil has lost beneficial microbes and earthworms, maintains Tucson Organic Gardeners member Rich Johnson.

He suggests removing the top 12 inches of your garden soil. Then fill the basin with water, allowing it to percolate into the ground. Do this three times. This pushes fertilizer salts deep into the ground.

Then replace the topsoil with compost.

"The number one key is to create an environment that worms would want to live in," Johnson says.

Add organic compost and fertilizer. Create your own compost or shop for officially certified organic amendments at retail garden centers, suggests MarciBeth Phillips, a biocontrol specialist with Arbico Organics.

Also look for sources that follow organic-growing practices. One place she suggests for manure is Hickman's Family Farms.

You want to use compost from plants without pesticides, herbicides or genetically modified organisms (GMO) and manure from animals raised without antibiotics or growth hormones.

Plant organic seeds and seedlings. These are partly defined as open-pollinated and non-GMO plants, Phillips says.

"We're very fortunate here," she says, because there are several local sources of these types of seeds and seedlings. These include Native Seed/SEARCH, Aravaipa Heirlooms and the Pima County Library's seed library.

Any plant grown organically will yield organic seeds, she says.

Use less-toxic pest- and disease-control methods. Here are some ideas:

• Decide how much damage you're willing to tolerate, says Peter Warren, director of the Pima County Cooperative Extension. "It's good to know so you can be prepared to act when necessary," he says.

• Plant complementary crops. For instance, onions and garlic planted around potatoes discourages insect pests, says Emily Rockey, horticulturist at Tucson Botanical Gardens and an organic gardener.

• Try high-spray water or soapy water to get pests off plants.

• Buy pest-eating insects at places like Arbico Organics.

• Purchase natural or organic pesticides and herbicides.

Many products for organic gardening are now readily available at many gardening centers, Phillips says, because of its growing popularity.

"It has joined the mainstream," she says.

Learn about organic gardening from these resources:

• Tucson Organic Gardeners' Spring Fair, 10 a.m.-2 p.m. Saturday. It's in the community garden at St. Mark's Presbyterian Church, 3809 E. Third St. The group also holds regular meetings.

• Pima County Cooperative Extension demonstration gardens and talks, 626-5161.

• Community Food Bank of Southern Arizona workshops, 882-3303.

• Farmers markets.

• Tucson Botanical Gardens' compositing demonstrations, 326-9686, Ext. 19.

Whether you practice organic gardening or not, here are some gardening tasks to do in March, according to horticulturists at the Tucson Botanical Gardens:

• Keep covers ready for possible late frost early in the month.

• Spring planting season commences, including herbs, trees, shrubs, corn, tomatoes and peppers.

• Prune perennial herbs.

• Watch for aphids on new plant growth. Use soap and water to remove them.

• Remove caterpillars that can eat up flowering plants.

Contact Tucson freelance writer Elena Acoba at acoba@dakotacom.net