Written By Lara Wadsworth

If you've ever looked at a patch of grass or weeds in your yard and envisioned a flourishing garden in its place, you're not alone. Converting lawn space into productive garden beds is a rewarding endeavor, but manually removing all those grass and weeds can be daunting. Enter solarization—a simple, effective method that uses the sun's energy to prepare your garden bed with minimal effort. Let's dive into how you can kill grass and weeds in an area to transform it into a garden bed for vegetables or flowers.

What is Solarization?

Solarization is a non-chemical method for killing plants, particularly weeds and grass, by harnessing the sun’s heat. Covering the area with a plastic sheet amplifies the sun's heat, and therefore, the soil reaches temperatures lethal to plants and undesirable organisms. The plastic sheet also suffocates the plant life and prevents respiration, further preventing them from surviving. This process is gaining popularity in the gardening world for its low manual labor and compatibility with no-till methods.

Advantages of Creating New Garden Beds With Solarization

Solarization is most loved for its eco-friendly benefits and lack of labor required. This method eliminates the need for chemical herbicides in this typically herbicide-filled gardening process. It is environmentally friendly and cost-effective.

Compared to other methods of turf removal, solarization requires minimal materials and labor. Because you are not removing the turf but instead killing it in place, those nutrients decompose into organic matter and can increase the availability of nutrients in the soil.

Lastly, solarization impacts the soil and the plant life on top of it. It is a great way to hit a big red ‘reset’ button for the soil. The heat generated can kill harmful pathogens and pests, leading to healthier soil. If you have struggled with soil-borne pests or diseases in the past, this can be an easy and chemical-free way to start anew.

Disadvantages and Drawbacks of Solarization

The biggest disadvantage of solarization is time. This process can take 4-8 weeks, depending on the climate and weather conditions. Additionally, it is best completed during the hottest months of the year, when the sun’s rays are at their peak intensity. Therefore, you may need to forgo having a garden in that spot for one year to complete this process.

Another downside is that it uses a lot of plastic. The use of plastic sheets may not align with sustainable practices. However, you can buy plastic tarps made of recycled plastic to use, reuse the plastic for other projects, or solarize another area with the same tarp.

Solarization can temporarily reduce the population of beneficial soil microorganisms; however, evidence suggests that they usually recolonize quickly, especially when compost is applied after solarization.

Lastly, in some cases, solarization has variable effectiveness. Very deep-rooted weeds or pests that escape the heat can occasionally linger and then return after the tarp is removed. These may require manual or chemical assistance for permanent removal.

Step-by-Step Guide to Solarizing

Step 1: Timing and Location

First and foremost, you need to plan out when and where you want to do this. It is best to wait until the hottest part of the year. Those in North America plan for the June through August timeframe. Then, map out where you want to kill the grass. The area should be as level as possible and not have any routine puddling or pooling of water.

Step 2: Prepare the Area

Next, remove any debris and mow or cut vegetation as short as possible.

Step 3: Moisten the Soil

Thoroughly water the area until the soil is moist but not waterlogged. Moisture conducts heat better than dry soil and helps kill deeper root systems.

Step 4: Lay the Sheet

Spread the plastic sheet over the prepared soil. Clear plastic allows more sunlight to pass through, heating the soil more effectively than black plastic. You want 1-4 mil thick polyethylene plastic. If you need to use multiple sheets to cover your desired area, be sure to overlap the sheets by 3-5 inches to ensure the plants wiggle out. Ensure the plastic is in direct contact with the plants or soil surface.

Step 5: Secure the Edges

Secure the edges using soil staples, large rocks, bricks, or stakes. Use as many stabilizers as needed to secure the edges, not just the corners. Any air getting under the plastic will reduce the effectiveness of the process.

Step 6: Wait

Now, you let the sun do its magic! I recommend waiting at least four weeks. However, if you can leave it on all summer, two to three months would really ensure the job gets done. The exact timing depends on the ambient temperature and the root depth of the plants you’re trying to kill.

Step 7: Remove the Plastic

Solarization is complete if all the plants underneath look brown, yellow, or white. There should be no green patches anywhere. You can check the soil temperature. Effective solarization requires temperatures to reach at least 110 F six inches deep into the soil. Check the temperature during the hottest part of the day. You can carefully remove the sheet once you are confident all the plants are dead. If you want to reuse the plastic, let it fully dry before folding and storing it to prevent mold growth.

Step 8: Prepare for Planting

Now, you can prepare the area for planting. Avoid disturbing the soil too deeply, as this can turn up any seeds that might have survived and allow them to germinate. Simply dig enough to plant your plants and seeds, and then cover the entire area in a layer of compost. Lastly, top it off with a nice layer of mulch to seal it all in. Water it deeply to help the dead plant matter decompose effectively.

Removing turf to plant a garden doesn’t have to be a back-breaking task. You don’t have to use chemicals or buy expensive tillage equipment. Solarization offers a practical, eco-friendly solution that leverages the power of the sun to do the hard work for you. All you need is some advanced planning and plastic! You can use this method to prepare a vegetable garden, a flower bed, or even a lawn that needs to be reseeded. Whether you're a no-till organic gardening enthusiast or simply looking for an efficient way to start a new garden bed, solarization is a technique worth considering.

Lara Wadsworth, True Leaf Market Writer

I am a native of Southwestern Michigan, where I currently reside. I love all things plants! After completing a Bachelor's Degree in Horticulture, I found a dream work-from-home job that allows me to share my passion. Now, I spend my days writing for TLM, playing with my dog, eating delicious food with my husband, and plotting my next landscape or gardening move. I believe everyone should get down and dirty in the soil now and then. Happy Gardening!