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New Mexico State University

New Mexico State University

News Center

Microclimates and Mulches Give Garden Crops an Early Start

LAS CRUCES -- A well-planned vegetable garden begins early in the year before the first spring seeds are ever planted. Gardeners who adapt to growing seasons will have more productive harvests.

"The types of vegetables you can grow in your home vegetable garden are generally determined by the length of the growing season," said George Dickerson, horticulture specialist with New Mexico State University's Cooperative Extension Service . "The average number of frost-free days ranges from less than 150 in cooler areas of the state to 180 in southern New Mexico."

The length of the growing season can be manipulated by taking advantage of microclimates in the garden. "For example, in warmer climates, the growing season can be extended for cool-season crops like leaf lettuce by planting in the shade where it's cooler," Dickerson said. "On the other hand, warm-season crops like tomatoes and melons can be planted in spring on the warm, south side of a house to encourage early growth."

Row covers can be used to create artificial microclimates. "Woven polyester row covers have the advantage over clear plastic covers because they allow air circulation around the plants. Structures that surround plants with a layer of water help store heat during the day and release it at night to protect plants from frost," Dickerson said.

Planting garden crops on raised beds also promotes early growth. Raised beds warm up sooner in the spring than the rest of the ground, especially if one edge of the bed faces south.

"One of the most effective ways to warm garden soil early in the spring is to use black plastic mulch," Dickerson said. This type of mulch also helps control weeds and conserve moisture. "Quality black plastic mulches will contain small pinholes or woven fibers that allow the soil to breathe and water to penetrate."

Organic mulches like dried straw, alfalfa or bluegrass clippings will actually cool the soil. These can be used around cool-season crops during the summer to protect them from high temperatures. Check alfalfa and straw carefully for weed seed that may cause problems in the garden, Dickerson said.