Six Tips for Effective Weed Control

1. Let sleeping weeds lie

Kill weeds at their roots but leave the soil—and dormant weed seeds—largely undisturbed. Photo/Illustration: Brandi Spade

Every square inch of your garden contains weed seeds, but only those in the top inch or two of soil get enough light to trigger germination. Digging and cultivating brings hidden weed seeds to the surface, so assume weed seeds are there ready to erupt, like ants from an upset anthill, every time you open a patch of ground. Dig only when you need to and immediately salve the disturbed spot with plants or mulch. In lawns, minimize soil disturbance by using a sharp knife with a narrow blade to slice through the roots of dandelions and other lawn weeds to sever their feed source rather than digging them out. Keep in mind that weed seeds can remain dormant for a long, long time.

2. Mulch, mulch, mulch

Don’t give weeds the chance to see the light. Whether you choose wood chips, bark nuggets, straw, or even pine needles, keep the mulch coming to smother out weeds.Photo/Illustration: Michelle Gervais

Mulch benefits plants by keeping the soil cool and moist and depriving weeds of light. Organic mulches, in particular, can actually host crickets and carabid beetles, which seek out and devour thousands of weed seeds.

Some light passes through chunky mulches, and often you will discover—too late—that the mulch you used was laced with weed seeds. It’s important to replenish the mulch as needed to keep it about 2 inches deep (more than 3 inches deep can deprive soil of oxygen). In any case, you can set weeds way back by covering the soil’s surface with a light-blocking sheet of cardboard, newspaper, or biode­gradable fabric and then spreading prettier mulch over it.

If you choose to use this method on seldom-dug areas, such as the root zones of shrubs and trees, opt for tough landscape fabric for the light-blocking bottom sheet. There is a catch, however: As soon as enough organic matter accumulates on the landscape fabric, weed seeds dropped by birds or carried in on the wind will start to grow. For the bottom layer of fabric to be effective, these must be pulled before they sink their roots through and into the ground.

3. Weed when the weeding’s good

Young weeds go down much easier than older ones, so make the most of good weeding conditions. Photo/Illustration: Michelle Gervais

The old saying “Pull when wet; hoe when dry” is wise advice when facing down weeds. After a drenching rain, stage a rewarding weeding session by equipping yourself with gloves, a sitting pad, and a trug or tarp for collecting the corpses. As you head out the door, slip an old table fork into your back pocket because there’s nothing better for twisting out tendrils of henbit or chickweed. When going after bigger thugs, use a fishtail weeder to pry up taprooted weeds, like dandelion or dock.

Under dry conditions, weeds sliced off just below the soil line promptly shrivel up and die, especially if your hoe has a sharp edge. In mulched beds, use an old steak knife to sever weeds from their roots, then patch any open spaces left in the mulch.

4. Lop off their heads

When you can’t remove weeds, the next best thing is to chop off their heads. With annual weeds, dead­heading buys you a few weeks of time before the weed “seed rain” begins. Cutting back the tops of perennial weeds, like bindweed, reduces reseeding and forces them to use up food reserves and exhaust their supply of root buds, thus limiting their spread.

You will need pruning loppers to take down towers of ragweed or poke, or you can step up to a string trimmer equipped with a blade attachment to cut prickly thistles or brambles down to nubs. No matter which method you choose, chopping down weeds before they go to seed will help keep them from spreading.