Most weeds in a garden come from seeds already in the soil, and every weed that flowers adds more. That is why weeding feels endless, and also why it doesn't have to be. Work on the seed supply and keep bare soil covered, and each season there are fewer weeds to pull.

This follows the same principle as the rest of the site: identify first, then use the least disruptive method that works.

The short answer

  1. Know what you are pulling. Annual weeds and perennial weeds need different tactics.
  2. Never let weeds go to seed. Garden soil holds a bank of weed seeds that can wait years for their chance; don't add to it.
  3. Hoe or pull weeds while they are tiny, and work the soil as shallowly as you can.
  4. Cover bare soil with mulch, a crop, or a tarp. Weed seeds need light and open ground.
  5. Wear down perennial weeds by cutting them back again and again, instead of tilling, which spreads their roots.
  6. Treat vinegar and herbicides as targeted tools, not routine. Vinegar only burns the leaves, and strong vinegar can blind.

Identify the weed first

The right method depends on how the weed lives and spreads.

  • Annual weeds grow from seed, set seed, and die in one year. Summer annuals such as pigweed sprout in spring and seed from midsummer into fall; winter annuals sprout in fall and seed by early summer. Stop them seeding and they fade out.
  • Perennial weeds live for years and come back from roots, rhizomes, bulbs, or tubers, as well as from seed. Canada thistle, field bindweed, and quackgrass are the hard cases. Pulling the top leaves the root to regrow.

If you can't name a weed, your state Extension service's weed identification pages or its Master Gardener program can help. A name tells you whether pulling, hoeing, or patience will work.

Stop the seeds

Garden soil holds a seed bank: weed seeds that have built up over the years, many able to stay dormant for a long time until they are brought to the surface and get the light and moisture to sprout. The single most effective long-term habit is to remove weeds before they set seed.

  • Pull or cut summer annuals before they seed in mid to late summer, and winter annuals before they seed in early summer.
  • Keep seeding weeds out of a home compost pile. Most piles never get hot enough to kill weed seed; the composting guide explains the temperatures.

Hoe them small, and shallow

A weed is easiest to kill while it is a seedling with a tiny root. A few minutes with a hoe each week kills a flush of seedlings before it becomes an afternoon of pulling.

Keep it shallow. A stirrup hoe, a garden claw, or a rake skims the surface and cuts seedlings off. Digging deeper or tilling does kill most annual weeds, but it also brings a fresh batch of buried seeds up to the light, ready to sprout.

Flush weeds before you sow

For direct-sown crops, especially slow starters like carrots, use a stale seedbed:

  1. Prepare the bed as if you were going to plant, and water it.
  2. Wait for the first flush of weed seedlings to come up.
  3. Kill them with the lightest possible hoeing or a flame weeder, without turning the soil again.
  4. Sow your crop into the cleaned surface.

Most of the weed seeds near the surface have already sprouted and died, so the crop gets a head start.

Cover the soil

Weed seeds need light and open ground. Cover the soil and most never get going.

  • Mulch shades the soil and gives blown-in seeds a poor place to sprout. Pull existing weeds first, because established perennials come straight through. The mulch guide covers what to use, and why landscape fabric ends up as a weed bed.
  • Crops and cover crops shade the ground too. Close spacing, and a cover crop on beds that would otherwise sit empty, leave less room for weeds. The clay soil guide explains cover crops in a no-till garden.

Smother a bed with a tarp

To clear a weedy patch or a lawn for a new bed without digging, cover it.

  • Occultation uses an opaque tarp, such as black plastic or a silage tarp. Weeds sprout in the warm, moist, dark space underneath and die without light. Minnesota Extension advises leaving it for at least four weeks; it keeps working up to about six, then levels off.
  • Solarization uses clear plastic, which lets the sun through and heats the soil far more than black plastic does. It works best in the hottest, sunniest part of summer.

For either, water the soil well first, since moisture helps weed seeds sprout under the cover, and weigh down the edges so the tarp stays tight to the ground.

Wear down perennial weeds

Perennial weeds store food in their roots, and that store is what you are fighting. Canada thistle roots spread many feet sideways and down, and new plants grow from root pieces as small as half an inch.

  • Don't till them. Tilling chops roots and rhizomes into pieces that each grow a new plant.
  • Cut them back, again and again. Removing the top growth every two to three weeks through the season makes the plant spend its root reserves regrowing, without letting it build them back up. Expect it to take several years of steady effort for the worst offenders.
  • Dig out small patches if you can get all of the root, and keep watching the spot.
  • Keep the roots out of the compost. Bindweed and quackgrass rhizomes can survive a home pile.

Where vinegar and herbicides fit

Vinegar herbicides are acetic acid. They burn the leaves they touch but do not move into the roots, so they can kill young annual seedlings, while perennial weeds and established plants regrow within a week or so. Horticultural vinegar is far stronger than kitchen vinegar: at 11 percent acetic acid and above it can burn skin and cause severe eye injury, including blindness. If you use it, wear gloves and goggles.

Conventional herbicides have a place for perennial weeds that hand methods have not beaten. Choose a product labeled for that weed and that site, spot-treat rather than broadcast, and follow the label exactly, including whether it can be used near vegetables. Be wary of the reverse problem too: some lawn and pasture herbicides persist in grass clippings, hay, and manure and can damage vegetables for years. The compost guide explains persistent herbicides.

Sources and further reading