Pine needles make a good covering for the vegetable-garden soil. Photo by George Weigel

Mulch

This first line of defense is to cover bare ground with two or three inches of coarse organic material, such as straw, leaves, pine needles, shredded bark, and/or dried grass clippings from untreated lawns.

This covering deprives weed seeds of the light that many of them need to germinate, and it suffocates small weed seedlings.

You can’t cover ground where you’ve planted vegetable seeds (it’ll stop most of those, too), but you can mulch between plants in a raised-bed garden and between rows in a traditional garden plot.

Mulching also keeps soil-borne disease spores from splashing up onto plant stems, thereby infecting new plants. And when the mulch breaks down, it’ll add organic matter and nutrition to the garden soil.

Regular weeding patrols will give vegetable plants a chance to out-compete the invaders. Photo by George Weigel

Regular weeding patrols

Most weeds that pop up in vegetable gardens are annual ones, such as pigweed, lambsquarters, prostrate spurge, and hairy galinsoga. The good news is that because these are new weeds each year, they’re poorly rooted and easy to pull or hoe.

Regular de-weeding visits will keep weeds from getting a leg up on vegetable plants, giving those a chance to fill the space. As the vegetables grow, weeds will be shaded and become less of a problem.

Especially important is eliminating all weeds before they have a chance to go to seed. Weeds that produce mature seed heads can drop hundreds or even thousands of seeds per plant that increase future troubles geometrically.

Weed-preventers

Weed-preventers are granular products that stop the sprouting of new weeds.

One that’s particularly suited to edible gardens is Preen Natural Vegetable Garden Weed Preventer, a 100-percent natural product made out of corn gluten meal.

Granules can be spread over top of 600 kinds of existing plants without harming them and is effective at preventing 21 common vegetable-garden weeds.

As with mulch, the product is not intended to use over top of seeded vegetables because corn gluten meal can inhibit their germination as well.

Preen Natural Vegetable Garden Weed Preventer can be applied monthly for the best weed protection.

A sheet of plastic stretched over this bed will “solarize” the soil and deter weeds and disease pathogens. Photo by George Weigel

Solarizing the soil

An effective but little-known technique that can quell widespread weed buildups is soil solarization. This process involves stretching a sheet of clear plastic over the soil and letting the sun bake it for four to six weeks in early summer.

Soil temperatures can increase to 120 degrees or more under the plastic – particularly if it’s been amended with compost and dampened to a foot deep beforehand. That’s hot enough to kill disease-causing pathogens and produce fatty acids that are toxic to weeds and weed seeds.

The main down side is that gardeners have to give up those four to six weeks of summer-time growing in exchange for draining the weed bank.

Raised beds help reduce vegetable-garden weed problems by allowing denser, fuller plantings. Photo by George Weigel

Strategy Changes

Finally, a few cultivation techniques are helpful at tackling veggie-garden weeds.

One is disturbing the soil as little as possible when planting. Since most weeds that pop up in vegetable gardens are annual ones, limiting the tilling and digging of garden beds keeps weed seeds below the germination zone where they’ll stay dormant and eventually die.

Planting fully and densely also limits the amount of open space that weeds have to invade. Space so that vegetable plants just touch as they mature, and replant harvested crops with new ones ASAP before weeds have a chance to take advantage of the openings.

A third weed aid is gardening in raised beds with wide rows – typically four feet wide. This layout allows plants to be planted densely throughout (no empty space for rows) while allowing harvesting from around the perimeter.

Never stepping on the soil in these beds also prevents compaction and the need to till, which stirs up those buried weed seeds.