Best Mulch for a Vegetable Garden and How to Use It

What mulch does

Mulch is just a blanket of material over bare soil, and it earns its keep three ways. It holds moisture so you water less, because covered soil dries out far slower than soil baking in the open sun. It blocks most weeds by keeping light off the seeds that need it to sprout. And it keeps the soil from baking, so the top few inches stay cooler and more even on hot days.

Steady soil moisture also means steadier plants. Crops like tomatoes crack or get blossom end rot when the water swings from soaked to bone dry, and a layer of mulch smooths out those swings.

Best mulches for vegetables

You do not need anything fancy. The best options are cheap or free:

• Straw is cheap and clean. It spreads easy, breaks down slow, and stays light enough to tuck around small plants.
• Shredded leaves are free. Run the mower over a pile in fall, and you have a season of mulch for nothing.
• Grass clippings work in thin layers. Lay them no more than an inch at a time and let them dry, or they mat down and turn slimy.
• Wood chips are best for paths, not beds. They are slow to break down and can tie up nitrogen at the soil line, so keep them on walkways, not around vegetables.

What to avoid

A few materials cause more trouble than they are worth. Skip hay, which is full of weed seeds and will plant a fresh crop of weeds right where you did not want them. Keep dyed wood mulch away from food crops, since you do not know what is in the dye. And never pile mulch against the stems, because trapped moisture there invites rot and pests at the one spot the plant cannot afford to lose.

How to apply it

Lay it 2 to 3 inches deep across the bed. Less than that and weeds push through, more than that and water has trouble reaching the roots.

Keep it a couple inches off the stems so air can move and the base stays dry. Then refresh it as it breaks down, usually once or twice a season, since the material thins out as it feeds the soil. That is the whole job.