Is Putting Mulch Around Vegetable Plants a Good Idea?

Moisture Retention

• Vegetables require moist soils to grow well. Even temporarily dry conditions can damage the plant or reduce the future harvest. Mulched vegetable beds retain more moisture than unmulched beds. Mulches hold moisture in the soil by preventing or inhibiting evaporative water loss. Plastic mulches provide the most moisture retention because no water is lost through evaporation, but a drip irrigation must be installed beneath the plastic to facilitate watering. Organic mulches, such as straw, provide adequate retention in vegetable beds if a 2-inch layer of mulch is applied, though some moisture is still lost through evaporation.

Weed Control

• Weeds compete with vegetable plants, draining moisture and nutrients away from garden plants. Some weeds grow more quickly than the vegetables so they eventually block the sunlight and crowd out the plants. Weeds may also harbor harmful insect pests or diseases. Weeding is a time consuming process, but mulches can suppress their growth. Plastic mulches block the growth of all weeds while organic mulches suppress most weeds and those that do manage to sprout typically root poorly so they can be easily pulled from the garden.

Soil Insulation

• Summer vegetables require warm soil throughout the growing season, while cool-season vegetables grow better in cooler soils. Plastic mulch applied to a garden bed one or two weeks before planting in spring warms the soil for summer crops. It also helps retain the heat in the soil during short periods of cooler temperatures. Organic mulches insulate the soil, holding in cool temperatures if applied in spring or trapping warmth if applied in summer.

Other Benefits

• A mulched bed can result in cleaner plants and vegetables, since water and mud won't splash onto the plants during irrigation. This keeps the plants free of some soil-borne diseases that typically spread to the plant from soil getting on the leaves. A cleaner bed is also easier and less messy to work in, especially after rainfall. Organic mulches impart some nutrients to the vegetable bed as they break down over the growing season and when tilled into the soil at the end of the year. These nutrients and organic materials work to improve the garden soil for future crops.