Answered by the Garden Voila editorial team · Updated
Frequently asked question
Should I mulch my vegetable garden, what kind of mulch is best and how deep should it be?
Answer
Mulch is one of the most effective habits in vegetable gardening. A layer of organic material over the soil slows evaporation, suppresses weeds and moderates soil temperature. Colorado State University Extension reports that mulch reduces evaporation and can cut irrigation needs by about 50 percent, while also reducing soil compaction from rain and foot traffic.
Which mulch to use
- Straw: use certified weed-free straw. It also keeps potato tubers covered so they do not turn green, and can replace hilling.
- Grass clippings: apply in layers up to about 1/4 inch thick, letting each layer dry before adding more. Colorado State Extension says to avoid clippings from lawns treated with herbicides in the previous month, because some herbicides persist.
- Compost or leaf mold: apply 1 to 2 inches. Homemade, plant-based compost works best and feeds the soil.
- Wood or bark chips: keep these out of the growing beds. Between raised beds, 3 to 4 inches controls weeds and limits compaction.
- Black plastic: best for warm-season crops like tomatoes, peppers, melons and strawberries. It warms the soil early and can advance harvest by about two to three weeks in some regions. Use drip irrigation beneath it, bury edges 2 to 4 inches and cut planting holes rather than slits.
When to apply
Wait until the soil has warmed in spring so you do not slow warming of warm-season crops. After planting, spread mulch around plants once seedlings are established. In hot climates, mulching in late spring protects roots from heat stress.
Cautions
- Keep mulch off stems. Leave a small gap around plant bases to prevent rot.
- Avoid thick layers of grass. Deep piles mat, smell and block water and air.
- Avoid fine sawdust, which can tie up nitrogen and block water.
- Watch for herbicide carryover in straw, hay and clippings. Read labels and ask suppliers.
- Remove plastic in fall and discard it, since it does not break down in soil.
How mulch saves water and work
Because mulch holds moisture, you can water less often but more deeply. Use our garden watering calculator to estimate needs and the mulch calculator to find out how much to buy. Weeds that do come up are easier to pull from loose, mulched soil.
Next season
Organic mulches break down and feed the soil. Work leftover straw or compost into the bed in fall, or add a fresh layer in spring.
Source
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