Warm weather has finally arrived, which means it's time to mulch your gardens. Summer mulch can be a gardener's best friend: It reduces plant stress by evening out soil temperatures. It also helps keep the soil moist and keep weeds at bay by depriving them of the light they need to germinate. Here's a guide to help you sift through the choices. COCOA BEAN HULLS

Made from: The hulls of cocoa beans used in making chocolate.

Best use: Annual or perennial beds.

Benefits: Its dark brown color makes an attractive backdrop for many plants. And it really does smell like chocolate.

Drawbacks: It can compact. It's prone to mold in wet years. And it can be fatal to dogs if eaten.

STRAW

Best use: Annual flower beds, vegetable beds.

Benefits: Inexpensive or free. Adds organic matter when worked into the soil at the end of the season.

Drawbacks: Breaks down quickly. Can be a source of weed seeds. Fresh grass clippings can become smelly, so should be applied thinly or be dried before being used as mulch.

BARK

Made from: Bark from trees cut for lumber or paper.

Best use: Around trees, shrubs or long-lasting perennials.

Benefits: Attractive, readily available.

Drawbacks: Pine bark tends to be smaller than wood chips, so it breaks down faster.

CYPRESS

Made from: Shredded Gulf Coast cypress trees.

Best use: Around trees, shrubs or long-lasting perennials where it can be left on the ground.

Benefits: Inexpensive. It retains its color and has a nice smell.

Drawbacks: Some groups say harvesting cypress for mulch damages fragile coastal-wetland forests in Louisiana. Others dispute that claim, saying that regrowth exceeds harvest in the state.

COLORED WOOD CHIPS

Made from: These artificially colored chips often are made from recycled wood products

Best use: Around trees, shrubs or long-lasting perennials.

Benefits: Because it comes in many colors, your mulch can complement your house.

Drawbacks: There's some concern that it may leach the pesticide CCA (chromium, copper and arsenic) if it's made from pressure-treated wood. Look for the Mulch and Soil Council symbol, which designates CCA-free mulch.

MUNICIPAL MULCH

Made from: Tree trimmings conducted by municipalities.

Best use: Around trees, shrubs or long-lasting perennials.

Benefits: Free. Some municipalities require proof of residency.

Drawbacks: Not always available. Larger sticks and leaves can give mulch a less uniform look.

ROCK

Made from: Gravel, pebbles, lava rock, crushed rock.

Best use: Next to foundation of house, rock gardens, gardens with a formal design.

Benefits: Rock is forever.

Drawbacks: Leaves and other debris may be hard to remove from between rocks. Weeds can sprout from decomposed debris.

LANDSCAPE FABRIC

Made from: Synthetic water- and air-permeable fabric.

Best use: Under another mulch for weed suppression and erosion control.

Benefits: Very good at weed suppression. Lasts for several years.

Drawbacks: Doesn't work well if you want plants to spread. Needs to be covered with another more attractive mulch. Mulch covering can slide off fabric during heavy rain.

RUBBER

Made from: Recycled car tires.

Best use: Paths and children's play areas.

Benefits: It's long-lasting and is available in many colors, some quite bold.

Drawbacks: It's relatively expensive and smells like rubber. Wire fragments from steel-belted radial tires may be found in some lower-cost mulches, according to the Wall Street Journal. Some studies suggest these wires may leach zinc, which can inhibit plant growth.