To stop weeds from growing through the mulch in your flower bed or vegetable garden, use these methods:
- Choose a high-quality mulch
- Weed before mulching
- Lay down landscape fabric prior to mulching
- Apply 2–3 inches of mulch
- Add a stone or brick border to separate your garden from your lawn
- Use a pre-emergent herbicide to stop weeds from sprouting
- Keep your lawn weed-free
- Grow ground cover plants that smother weeds
- Selectively water plants to discourage weed growth
Each of these tips will help you toward your goal of preventing weeds from growing up through your mulch. By employing a few or all of these methods, as you see fit, you’ll be able to completely rid your garden of problem weeds and focus on growing your desirable ornamentals and vegetables.
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9 Tips to Stop Weeds from Growing Through Mulch
Weeds growing through the mulch in your garden are a real problem. Not only do they ruin the look of your garden, but weeds also rob nutrients and water from your soil—nutrients and water your plants need. In order to keep weeds at bay, choose the right materials for your garden. If done right, a weed-free garden can be maintained in an easy and cheap manner.
Choose the Right Mulch
Mulch is mulch, right? Not so fast. Some mulches work better at stopping weeds than others. The best mulches to prevent weeds from sprouting in your garden are:
- Shredded bark mulch
- Wood chips
- Cocoa hulls
These mulches won’t blow away or decompose quickly enough that weeds can take root. When choosing organic mulches that resist weeds, go with wood, bark, or nut husks.
Avoid using leaves, pine needles, and grass clippings as mulch if you’re battling weeds in your garden. Grass clippings often carry weed seeds with them, which can introduce additional weeds in your garden. Leaves, pine needles, and grass clippings also decompose quickly, giving weeds more chances to sprout.
Weed Before Mulching
When laying new mulch or replenishing existing mulch in your flower bed, rake aside any existing ground cover or mulch and pull up any weeds present. By killing weeds before adding new mulch, you reduce the chance invasive plants will pop up through your ground cover.
Mulch is an effective weed barrier because it prevents light from reaching young weed sprouts. Established weeds may have enough stored energy to grow up through mulch, so root these weeds out to prevent an invasion.
Lay Landscape Fabric
A water-permeable weed barrier, such as landscape fabric, is one of the best weed control tools for your garden. It allows water and nutrients to reach the soil but also provides a physical barrier against any plants trying to sprout from the soil.
Lay landscaping fabric directly on top of the soil before mulching. Cut holes for existing plants and when you plant new desirables. The barrier of fabric between the mulch and soil will go a long way toward stopping weeds from growing through mulch.
Lay Thick Mulch
In order to form an effective barrier against weeds, mulch should be 2–3 inches (5–7.5 cm) deep. A deep layer of mulch will prevent weed seeds from reaching the soil, as well as choke out any weed sprouts before they break through to the surface—the pesky seedlings will die before you ever see them.
Add a Border
You may think of mulch as your only weed barrier, but a lot of weed problems in flower beds and gardens are caused by encroaching weeds. Encroachment is when grasses or weeds in your lawn begin to send roots and runners into your garden. If there’s no border, soon these plants can overtake your mulched areas.
To prevent this, dig a trench around your garden and lay a border of rocks, bricks, stones, or pavers. Not only can these features be attractive, but they also stop encroaching weeds.
Use a Pre-Emergent Herbicide
Pre-emergent herbicides kill seeds just as they sprout, but does not harm mature plants and grasses. In spring, spread a pre-emergent in your garden. It will form an anti-weed barrier for up to 6 weeks, killing perennial weeds as they sprout. The best part is, there’s no risk of harming your mature, desirable plants with a high-quality pre-emergent product.
Keep your Yard Weed-Free
The same way weeds and grasses can encroach on mulched areas through roots and runners, weed seeds can also be carried into your garden from other parts of your lawn. To help prevent weeds seeds from getting into your mulch, work to keep your lawn weed-free.
When you apply pre-emergent herbicide to your garden, apply it to your lawn as well. Practice proper lawn maintenance, such as fertilization and weeding, to prevent perennial and annual weeds from invading your mulched areas.
Grow Ground Cover Plants
Weeds grow best in the areas between established plants. If you’re fighting a battle with weeds in your garden, consider simply planting varieties that sprawl and cover the ground. Fill your garden with attractive, aromatic plants to choke out weeds.
Rosemary, Mint, and Catnip are just a few examples of plants that humans (and animals) love that function as excellent ground cover, growing quickly and spreading in areas between other plants. If you want to stop weeds from growing in your mulch, simply don’t give them room to grow.
Water Plants, Not Weeds
Like all plants, weeds love water. Starving weeds of water is an effective method of weed control.
To water your plants without watering weeds, use the correct type of irrigation. Instead of sprayer or watering can, lay a soaker hose that coils around the base of your garden plants. For even more targeted watering, use a drip irrigation system that only disperses water at the places you want it to. You can set this up so that it only waters your desirable plants. Weeds won’t receive water and thus won’t sprout up in your mulch.
Best Ways to Prevent Weeds in Mulch
Preventing weeds from growing through mulch all comes down to your mulching process. It’s essential to choose the right organic mulch (such as wood chips), weed before mulching, lay landscaping fabric, and then spread 2–3 inches of mulch in your garden.
After mulching, consider other methods of creating a weed barrier. Lay a brick border around your garden to prevent encroaching weeds, apply a pre-emergent herbicide to stop weeds from sprouting, and attack the weeds in your yard so seeds are less likely to blow into your garden and take root in your mulch.
Finally, plant some additional ground cover plants to choke out weeds and water with a soaker hose or drip line irrigation to make sure only your desired plants get water. Depending on your garden, one or more of these options will be right for you. The good news is, each and every one of these is simple and a great way to keep weeds out of mulch.