Do You Need to Remove Grass Before Laying Mulch?

So, you’ve decided that your property has too much lawn! What’s next for your yard? Planning to replace grass with garden beds? Or are you simply going to create mulched areas to cut down on your mowing and watering needs? Either way, the first thing that you have to consider is what to do with the grass currently growing in those spots. Whether mulching is a permanent or temporary solution, doing it right will help guarantee that grass stays gone!

Do You Need to Remove Grass Before Mulching?

You usually do not need to remove grass before laying down a layer of mulch. Done properly, the mulch itself will smother and kill the grass all on its own! However, it will take a season for that process to complete, so if you want to get rid of the grass on a shorter schedule, you will have to consider manually removing the grass before proceeding.  

The other time that removing the grass before mulching makes sense is when you want a flat, hard surface underfoot. This would be the case if you’re creating an area for walking or setting up outdoors furniture, for instance. You will want a perfectly level surface from the beginning.

Do You Need to Remove Weeds Before Mulching?

You don’t necessarily need to pull or dig out weeds before mulching. Annual weeds will get smothered effectively without having a chance to flower and set seed. However, stubborn perennial weeds with deep taproots or a creeping habit can end up growing right through the mulch, so you should definitely dig them out before proceeding with mulching.

What Happens if You Don’t Remove Grass & Weeds Before Laying Mulch?

If you don’t do a through job of smothering grass and weeds, and they end up growing through the layers of mulch that you’ve laid down, the resulting plants will be hale and hearty, no doubt given a feeding boost by the nutrients in the mulch. You may end up having to clear everything away and starting again. That’s why you shouldn’t rush the planning and prep stages in a mulching project.

How to Kill Grass Before Laying Mulch?

1. Manually Dig/Pull Up Grass

The most through way to prepare the ground for mulching is by removing the grass before mulching

The most through way to prepare the ground for mulching is by removing the grass (and weeds!) before mulching. If you’re doing a small section, simply get out a flat-edged shovel and start at one side, cutting the sod and sliding the shovel underneath horizontally to cut off the plant roots. Roll it up as you go, and when you reach the end make a clean cut to detach the sod. Keep going until the whole space is cleared of grass. For larger sections of grass, you can rent a sod cutter to make the job easier.

And now you have some fresh sod that you can use to patch bare spots in your lawn! If you have no use for the sod, simply stack the turves upside-down in a back corner of your yard. You should have a pile of excellent compost in a year’s time.

2. Smother the Grass

I’ll admit, I’m lazy, and usually I can wait a season to let the grass get killed slowly. All you need for this is stuff to cover up the grass and smother it, letting the plants die and turn into topsoil. If you have access to piles of newspapers, simply lay down thick layers over the entire surface, wetting them down to keep them from blowing away before you get them covered up. Cardboard is another great free material to use for smothering grass. You can cover these bio-degradable layers with shredded bark or rough compost. Within a few months the grass will be gone, and the paper or cardboard will start to break down, leaving you with an excellent bed to plant in.

Some people use old carpeting or black plastic to smother grass, but unless your future mulched area is out of the public eye, think twice about using these materials, as they are going to look terrible until they’ve done their job. They won’t break down, so you will need to remove them before you can use your now grass-free plot as a garden, or to lay a layer of permanent mulch over top.

This is definitely the cheapest way to kill grass!

3. Kill Grass Using an Herbicide

To get rid of grass quickly you can use an herbicide

To get rid of grass quickly, you can use an herbicide, but don’t immediately rush for a toxic chemical solution! Both horticultural vinegar and citric oil formulations can kill grass and weeds, leaving you with a blank canvas to cover with mulch. Because you will be smothering any new growth with the mulch, using these organic products should suffice.

What’s the Best Way to Kill Weeds Before Mulching?

The best way to kill weeds before mulching is by digging them out. While annual weeds won’t survive being covered up for any length of time, perennial weeds such as dandelions or burdock have deep tap roots that can support the regrowth of the plant, even if all its above-ground parts are chopped off at the soil level. Make sure you dig down and get as much of the roots as possible, as they can potentially regrow from even a small piece that gets left behind!

How to Prevent Grass and Weeds from Growing through Mulch?

1. Lay Landscaping Fabric

Landscaping fabric is best used under mulch when you’re not planting the area

Landscaping fabric is best used under mulch when you’re not planting the area. If you are mulching a garden bed where you’re planning to install perennial and annual ornamentals, for instance, you may find the landscaping fabric getting in the way, and every time you cut a hole in the fabric to pop in a plant, you’re providing a spot for weeds or grass to sneak through, too!

As well, over time as your wood mulch over top starts to break down, the new soil that is created will be sitting on top of the landscape fabric, creating the perfect conditions for unwanted seeds to sprout. Then the roots end up growing through the fabric layer from above, creating a real mess.

The one exception would be in a bed with just a few herbaceous perennials such as hostas, or shrubs that will be staying put for years, or an area that you’re spreading with mulch and not doing any planting at all. Then, the landscaping fabric won’t interfere with your plantings.

2. Apply the Correct Amount of Mulch

The mulch will prevent any seeds from finding some soil to sprout in

Do not be afraid to use lots of mulch, and to renew it whenever it starts to look a bit thin! The mulch will prevent any seeds from finding some soil to sprout in, and if one or two manage to germinate on top of the mulch, they’re easy to pull out. Mulch also holds in soil moisture, decreasing the need for watering, so it’s really a win-win strategy. Over time, shredded bark or wood mulch will break down, improving the soil quality, so it does need to be replenished annually.

Read our related post “Will Grass Grow Through Mulch?” here.

3. Good Edging Prevents Seeds Coming In

You can avoid having plants moving in around the edges of your mulched patch by installing good quality edging around the perimeter. This will also keep your mulch right where you want it, creating a more finished look. Otherwise, you’re going to end up with some of your mulch on your lawn.

4. Treat Mulch with Pre-Emergent Herbicide

Over the years, you may find some weeds and grass sprouting in your mulched beds, despite your best efforts. For minor problems, simply hand-pull the sprouting plants, but if it’s an ongoing problem, you can apply an annual treatment of pre-emergent herbicide in early spring before new seeds germinate.

Final Thoughts

Mulch has a lot of uses in the landscape, and can really cut down on ongoing maintenance tasks when used properly. Take the time to prepare the areas you want to mulch, and grass and weeds will be much less of a problem!

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