How to keep weeds out of mulch?

Will weeds grow through mulch? What can I put in my mulch to prevent weeds?

Weeds are tenacious and can survive several methods of preventing or eliminating them. One of the easiest ways to control weeds is mulching, which prevents weed growth by blocking out the sunlight, aside from maintaining soil moisture.

However, it is not 100% effective, and some weeds might still grow. So, how can you prevent this from happening?

The best way to keep weeds out of mulch is to use proper weed prevention techniques before planting. Unfortunately, this makes it impossible for most weeds to grow once you plant crops.

Below, we have compiled information on preventing the growth of weeds in mulched areas. We have also detailed several ways to get rid of weeds if they grow through the mulch.

How to prevent weeds in mulch beds?

As already discussed above, using mulch does not guarantee that weeds won’t grow through. Therefore, it is best to prevent the issue before it occurs.

There are several methods you can use to keep weeds from growing in your mulch, which include:

1. Spraying the soil with pre-emergent herbicides

Pre-emergent herbicides are one of the best weed control techniques, as they help kill weeds before they sprout. While preparing your garden, spray the soil with a pre-emergent weed killer.

Once done, you can then plant and apply your mulch.

2. Using a weed barrier

If you don’t like using chemicals in your garden, a weed barrier is another alternative. The weed barriers, usually fabric, are placed below the soil in your garden.

They allow water to seep through but prevent the weeds from growing through. While weed barriers are practical, they have a few drawbacks. First, they can be expensive and time-consuming to install in large garden areas.

Secondly, they will not prevent weed growth from the soil on the top. Another downside is that some weeds are stubborn and hardy enough to grow through the barriers.

3. Solarizing the soil

Solarizing the soil before planting is another method of preventing weeds from growing through your mulch. Again, the technique is appealing as it is a natural remedy and not expensive.

It also helps eradicate pests and pathogens – on top of killing weeds.

To solarize your soil:

Cultivate your garden to prepare it for planting.
Rake over the soil to make it smooth and level
Water the soil adequately with large amounts of water.
Cover the soil with a transparent plastic sheet or tap and secure it to the ground by placing heavy objects along the edges
Leave the soil covered for about four to six weeks or even longer (up to 8 weeks). Make sure to do this during the sunny season for the technique to work.

The clear plastic allows the sun rays to penetrate, heating the soil. It then traps the heat, raising temperatures to high levels and killing sprouting weeds, weed seeds, pests, and pathogens.

The downside of soil solarisation is that it takes a lot of time, which can delay your planting schedule significantly. The technique also kills beneficial organisms in your soil and thus requires you to enrich the soil with manure or fertilizers before planting.

How to remove weeds growing from mulch?

The above techniques can prevent weeds from growing once you have mulched. However, they are not always effective. Some weeds are stubborn enough to survive weed killers and other natural control mechanisms.

On top of that, you can transfer weed seeds to your garden after planting by birds, wind, or contaminated mulch.

Therefore, how can you eradicate these stubborn weeds despite taking all the precautions?

1. Using chemical herbicides

Weeds that have grown through mulch can be eradicated using post-emergent herbicides. There are several herbicides; you can find the most suitable one for your garden and crops by visiting the nearest gardening store.

Note: With most of these herbicides, you must first remove the mulch to apply them to the weeds directly.

Can you spray Roundup on mulch?

Roundup is a famous post-emergent weed killer (although you can find some pre-emergent roundup formulas). The active ingredient in the herbicide is Glysophate, which is very effective in killing weeds.

If you are dealing with weeds that have sprouted through your mulch, you can spray Roundup. However, it would help if you were very careful as it is not a selective weed killer, which means it is more than likely to kill your crops.

2. Using natural weed control mechanisms

A plant growing through mulch — Photo by: Flickr/Kathy

If you don’t like using chemical herbicides, natural weed control is another excellent alternative for weeds that have sprouted through your mulch. It is time-consuming, but it prevents the risk of damaging crops or contaminating your produce with chemicals.

So, how do you kill weeds in mulch naturally?

1. Pulling the weeds

Hand pulling is the easiest way to remove weeds from mulch. First, grab and pull any sprouted weeds. If they are tough to pull out, you can cut the top parts (with all the leaves), which will leave the plant to wither and die.

2. Using vinegar, salt, and soap solution

You can use several homemade weed killer solutions, such as a mixture of salt, vinegar, and soap. Salt will leech the weeds’ moisture, while the vinegar’s acetic acid will burn the leaves.

On the other hand, soap is a surfactant, which promotes the absorption of the solution into the weeds. The vinegar, salt, and soap solution are thus very effective at killing weeds.

However, it is not selective and can even kill your crops. Therefore, you should only spray it directly at the sprouting weeds.

3. By using a rubbing alcohol solution

Rubbing alcohol is another homemade remedy for controlling weeds. To make the weed killer, mix about two tablespoons of the rubbing alcohol with four cups of water.

Then spray the mixture directly to the weed leaves, avoiding your crops. Once in contact, the solution will cause the leaves to wither, thus killing the weeds.

Final thoughts

Mulching is a great gardening technique that keeps your soil moist while preventing weeds from growing. However, some weed plants are pretty stubborn and can withstand mulch cover.

Fortunately, with the above techniques, you can keep weeds from growing through your mulch and eradicate any stubborn ones that manage to sneak through.

Carla Etheridge

Carla is a student pursuing a B.S in Agricultural Systems Technology. With a passion for landscaping for over 4 years, Carla loves plants. She has previously contributed to several other sites in the space before joining InsightWeeds.