How Much Does Mulching Help Vegetables?

Weed Reduction

• Weeds are harmful to vegetable gardens because they sap soil of nutrients and carry or make plants susceptible to disease. Mulch smothers weed seeds and blocks sunlight, preventing weeds from germinating and reducing the amount of time you have to spend weeding. Mulch works best to fight annual weeds. Although perennial weeds with taproots can still survive even the best mulch job, mulch keeps soil moist, which makes dandelions and other weeds easier to pull. For best results against weeds, use a 2 to 4-inch layer of mulch like grass clippings, leaves or aged wood chips, or one layer of black plastic.

Moisture Conservation

• Without proper water, vegetable plants show reduced growth and disease susceptibility. Mulch prevents water loss from evaporation and helps soil absorb water slowly during heavy rain. This can decrease watering frequency and protect vegetable plants during especially hot weather. An added bonus is that mulch absorbs water so that it does not splash onto fruit after rain. Because moisture is a major cause of fungal disease for vegetables, mulching can effectively reduce the likelihood of common diseases such as fruit rot on tomatoes.

Soil Temperature

• Applying plastic mulch early in the season warms the soil and help new plants grow more quickly. Likewise, organic mulch can insulate plants from cold temperatures when applied later in the growing season. Using straw mulch for cool-season vegetables like cabbage and broccoli can help keep them productive in warm temperatures, although straw can diminish growth of warmth-lovers like tomatoes, peppers and melons. Instead, for warm season vegetables, use dark landscape fabrics that warm the soil quickly. According to Michigan State University, landscape fabric or dark plastic mulch can increase melon production by 50 percent. Colorado State University states that Colorado crops produce up to three weeks earlier when plastic mulch is applied. Avoid using landscape fabric or plastic on cool-season crops, since it will overheat them.

Fruit Quality and Yield

• Vegetable plants need high-quality soil packed with organic matter in order to thrive. A long-term benefit of organic mulch is its ability to feed the soil as it decomposes. Mulch can improve soil texture, add nutrients and improve its ability to hold water. According to Texas A&M University Extension, proper mulching can increase vegetable production by 50 percent compared to un-mulched gardens. Selective reflecting mulch, such as red plastic, has also been shown to improve fruit quality for strawberries and tomatoes. According to Michigan State University, red plastic mulch also increases tomato production by 12 to 20 percent compared to black plastic.