Mulching is perhaps one of the simplest ways to keep weeds at bay. A two to three-inch layer of quality mulch not only prevents weed growth but also improves soil health and retains soil moisture.
However, it’s disappointing to apply the mulch and think you’ve won the battle only to see the weeds popping through the layer a few weeks later.
What can you do to tame them?
Let’s look at helpful ways to keep weeds from growing in a new or existing mulch bed.
Preventing Weeds in a New Mulch Bed
The best tactic here is to combine the dynamic duo of landscape fabric and mulch. All you need to do is clear any weeds and spread landscape fabric before laying the mulch.
The fabric acts as a barrier between the weeds and the soil, preventing germination. The best part is that landscape fabric can last two to five years, depending on the thickness.
Whole_Gate7961 on Reddit also recommended using cardboard, which could give the same results.
“I’ve used cardboard under the mulch pretty successfully. “It’ll break down within a couple of years.”
Preventing Weeds in an Existing Mulch Bed
For an existing bed, hand-pull the growing weeds from the roots or spray them with a commercial weed killer containing glyphosate. As always, be careful not to spray on the foliage of your desirable plants.
Once the weeds are out, apply a pre-emergent product, preferably one with an active ingredient such as prodiamine or pendimethalin. As the product is watered in, it will settle under the mulch and prevent the growth of future weeds.
A gardener on Reddit also recommends edging the garden bed to prevent stray weeds from invading your mulch.
“What this does is it keeps the grass (and other weeds from migrating from the lawn into your bed.”
Is there a Permanent Solution to Keep Weeds from Growing in the Mulch?
Despite the best efforts, no technique can permanently prevent weeds from growing in your mulch. The pre-emergent application will break down after 5-6 months and will require reapplication.
Some weeds may require additional removal measures like hand pulling and the mulch requires relaying yearly. That said, applying these measures will give you more time to enjoy your landscape and probably just once a month of weeding.
Lead Editor for Insight Weeds.