How to Kill Weeds Naturally with Solarizing Plastic

Are you looking to kill your lawn or remove weeds from an area without having to use herbicides? Solarization is great way to kill weeds naturally. It uses strong plastic sheeting and the power of the sun to kill weeds and unwanted turf grass. Solarization is often used to prepare an area for a pocket prairie or wildflower bed, as seeds perform best when sown on bare, weed-free soil.

Here’s how to harness the power of the sun this summer to solarize an area of your yard!

How to Use Solarization to Kill Weeds

I have used this technique twice at local schools to create pocket prairies / wildflower beds. These photos are from a recent morning setting out solarizing plastic with fellow Native Plant Society volunteers. We are letting the plastic to do its magic over summer break, so the ground will be ready for sowing pocket prairie seeds with the students in the fall!

This technique works best in a full sun area, and during the hottest months of the summer. You can try either black or clear plastic sheeting – there is is an ongoing debate of which works better – but I am a fan of black! Just make sure you get the thickest plastic you can find so it doesn’t rip.

Solarizing Supplies

• Black Plastic Sheeting (at least 6 mil. thickness, the thicker the better). We used a 10′ x 100′ ft. roll.
• 2″x4″x12″ lumber (to hold down plastic).
• Bricks or rocks to further hold down plastic.

Step 1: Measure and mow the area

Determine dimensions and location of your prairie before laying out plastic. Make sure get enough plastic to cover the square footage of the area.

There was only minimal vegetation in the area below where we are solarizing, however if you have a lot of existing grass and weeds, you want to mow them close to the ground before covering with plastic.

Step 2: Layout plastic sheeting

Open the plastic and lay it in place. If you are using multiple lengths of plastic, be sure to overlap each piece by several inches. This will prevent any sunlight from getting in. Be careful with the plastic when handling it so you don’t rip any holes in it.

Step 3: Lay lumber around the perimeter

Use 2″x4″x12″ pieces of lumber (or similar) to hold down the edges of the plastic. This is one of the best ways to hold the plastic in place, but you can also use landscape staples around the edges instead. The drawback of using staples is that the plastic can rip and let in sunlight.

Step 4: Secure the plastic in place

Here is a cool trick I learned from my volunteer friend George – you can wrap the lumber up in the plastic to completely secure it in place. Just roll up the plastic with the lumber a couple times to secure it. This trick eliminates the need for landscape staples!

Step 5: Secure any overlapping areas.

Use lumber across the middle (where two lengths of plastic overlap) to hold it in place. Use rocks or bricks if needed to futher secure plastic to ground.

Step 6: Let people know what you are doing!

Add a sign so people know what the plastic is for, and to discourage anyone from walking on it. Leave plastic on for at least a couple months to solarize the area.

Cardboard and Mulch Trick

Here’s a great alternative to solarization to kill weeds if you plan to use transplants instead of sowing seeds. A layer of cardboard and shredded wood mulch will suffocate any existing weeds and grass and prevent future weeds emerging in garden beds. It is one of my favorite garden hacks! Get the details here.