Do Weeds Have to Be Pulled Before Mulch Is Applied?

Hand-Pulling Weeds

• Hoeing weeds or pulling them by hand prevents them from flowering and distributing seeds to other parts of the garden. You must eliminate all of the roots to prevent them from growing back. This makes pulling weeds a necessary step in eliminating a weed problem in the long term, which you should follow up with the layer of mulch. You may also need to hoe or hand-pull a few weeds, such as the occasional dandelion, that make their way through the layer of mulch. Fortunately, the mulch layer should keep the soil moist enough to make pulling up stubborn weeds a breeze.

Laying Down Mulch

• Although a layer of mulch doesn't kill most existing weeds, it blocks sunlight from the soil to prevent weed seeds from germinating. This makes it an effective method of long-term weed control, especially after you've already pulled weeds that have germinated and begun to grow. Just keep in mind that mulch is most effective for annual weeds, and you shouldn't apply it around desired seeds in the garden that need to germinate.

Controlling Perennial Weeds

• Perennial weeds are almost impossible to control with mulch. Compared to annual weeds, perennials have more energy stored in their roots or rhizomes, which allows them to push strong sprouts upward through layers of mulch -- even thick ones. Hand pulling, along with application of herbicides, is a more effective method of eliminating them, but you may need to perform this maintenance for several years to gradually reduce the number of weeds to zero. The key to controlling them is making sure you remove them before they produce seeds.

How to Mulch for Weeds

• Before you mulch, make sure the materials don't contain weed seeds. Because straw and hay are more likely to host seeds, skip them in favor of yard waste such as grass clippings and fallen leaves. In areas without other plants, plastic coverings and bark chips can be even more effective at blocking sunlight. Apply the mulch in a 2- to 4-inch layer over the ground, but keep them from touching desirable plant stems and trunks to prevent rot. Afterward, remove weeds as soon as you see them grow through the mulch.