How to Use Hay to Control Weeds in a Vegetable Garden

You may want to use hay rather than straw as a weed-controlling mulch in a vegetable garden, since spoiled hay is often cheaper than straw. Hay can add its own weed seeds, though, and may make the problem worse, if you're not careful. Straw contains the stems of grain after the wheat, oat or rye seeds have been threshed out, but hay includes whatever the farmer mowed in a grassy field, with its seeds intact. If you take care to prevent new weed seeds from germinating, hay can be an inexpensive, effective way to smother weeds.

Newspaper

Knife or scissors

Ask if the hay is from the first or later cuttings before you purchase it. First-cutting hay, mowed early in the year, may include spring grasses and weeds that went to seed. Later cuttings may have fewer seeds and contain more leaves and grass. Look for rectangular bales rather than large round bales, to make transportation and spreading easier.

Examine the hay and select hay that appears to have the fewest seeds. To identify seeds, look for stems with lots of small branches like grass that's gone to seed in an unmowed yard.

Purchase older hay that has spent time out in the rain and partially rotted. "Spoiled hay" is cheaper, since it's not healthy for livestock, but the exposure may have caused weed seeds to germinate and die already or may have rotted them so they won't germinate.

Hoe or cultivate the garden to turn under any high weeds that are already growing, since new, small weeds die more quickly from being smothered with mulch, while older, established weeds may be able to break through.

Spread four to six layers of newspaper on the soil before adding hay mulch to the garden, to prevent any seeds in the hay from reaching the ground. Leave the soil exposed for 2 to 3 inches around the rows where you plan to plant vegetable seeds. If plants are already growing, leave a few inches of space around their base. "We have found that the newspaper helps keep the seeds out of the soil, and it hasn't been a serious problem," Henry Homeyer writes in "Notes from the Garden."

Cut the strings holding together a rectangular bale of hay with a knife. Peel off a "flake" or square slab of hay about 6 inches thick. It will naturally separate from the bale. Lay it on top of the newspaper, making sure it doesn't cover the lower leaves of any vegetable plants that are already growing.

Separate and lay other flakes to cover the newspaper in an even layer.

Leave the hay on the garden during the summer and allow it and the newspaper to naturally decay before the next season.

Spoiled hay or hay stored in a damp area may contain mold or mildew. Wear a mask to avoid breathing the dust while you're working with it.

Hay mulch is flammable when it's dry, so be cautious with fires nearby, such as when using a propane flame weeder, burning trash or smoking.