Solarization — Turning On Nature's Oven
The Natural Way to Reset Your Soil
🔨 How‑To Garden Guide | by Guy Saldiveri | September 7, 2026
Its benefits include the removal of just about all living organisms in the first few inches or so of soil. The downside — it removes all living organisms in the first few inches or so of soil.
Ok, that might seem a little bipolar, but believe it or not, it really isn't.
Solarization is very good at removing unwanted weeds, killing off hidden seeds, and destroying many pathogens that can harm your crops. The downside is — it doesn't discriminate. It'll take care of the bad, but it will also take care of the good. I've done it before to sterilize a small section of ground, but I do so sparingly.
A couple of things to note before we really get into things:
I'm using the term sterilization a little loosely here. Once solarization is complete, the levels of pathogens, bacteria, fungi, etc. in the soil will (or should be) greatly reduced. But it won't be surgically-sterile. It will kill off grass, weeds, and hidden seeds; and it will greatly reduce the things you're trying to get under control, but it depends on how things are done.
Also, keep in mind, this is different from putting down a cover tarp or landscape fabric to control grass and weeds. They have their purpose, but pose their own problems as well. While they stop grass and weeds, they usually don't kill off many pathogens. And honestly, they can actually cause more issues with anaerobic soil — but that's a different subject.
What is solarization?
Solarization is the process of laying down a sheet of clear plastic and letting it bake in the sun for a period of time — usually on the order of weeks to months — to kill off anything growing underneath.
Research shows that 4 mil clear plastic works very well for solarization. It's thick enough to hold up against the weather, but still thin enough to let the heat build up underneath.
Now, that will take care of the grass, weeds, seeds, and diseases, but it will also clear out the beneficial bacteria, fungi, and worms.
How much it clears out depends on:
- The time of year and available heat
- The material used
- Your soil's structure
- Your soil's moisture
- The overall length of time it's implemented
Now, you may have seen (or heard of) folks using black plastic instead of clear plastic and wondered if there's a difference. The answer is yes, and believe it or not, it's the clear plastic that provides the better results.
Solarization relies on the sun's rays to heat up the soil. Clear plastic traps heat the same way a greenhouse does. Visible light passes through and gets trapped, converting into thermal energy that bakes the soil. Now, we aren't talking boiling point heat here, but if done correctly, it will provide enough heat to burn your skin. And that's exactly what you need to cook off those persistent pathogens.
Black plastic will certainly trap heat and block sunlight. That alone helps kill off grass and weeds. But because the plastic absorbs the heat on top, it doesn't leave enough heat at the soil level to cook off most of those hidden seeds or pathogens. Now, if smothering top growth is all you're after, this works very well, and color doesn't even matter much. You could drop a cheap tarp down and get the same results — which I do quite often as a temporary fix.
Using the clear plastic not only traps the heat, but allows the sun's rays in, so you get even more energy directed at your target.
How long does it take?
Excellent question! And once again in these situations, my answer is a resounding, "It depends." Yep, I went there again — gave you all the hard facts and went and got all wishy-washy on you. In my defense though, if you look back up at those bullet points I dropped in under the "How much it clears out" section, you can see why.
It depends on the time of year, your soil's structure, its moisture level, and the amount of time you spend covered up.
The hotter it is, the more heat you build up, and the faster you go. And by the way, soil moisture makes a big difference in your results. Water conducts heat much faster and more efficiently than air. Having your soil moist will greatly decrease the amount of time required to do the job.
To get you in the ballpark though, early- to mid-summer would be the most efficient time to start, and you should plan on being covered up for at least 4 to 6 weeks.
So, what's next?
Ok, so now we’ve gone through the process, killed off everything we needed to kill off, and lifted the plastic. What now?
Well, right now you should be looking at a bare patch of soil. No grass, no weeds, no leftover mush — just plain, clean ground that's (hopefully) clear of pathogens.
Now you get to start fresh. You can amend the area how you want, so you can grow what you want. You can layer in some compost, some fertilizer, and maybe some lime to balance everything back out again. Remember, you just spent the last month or so killing everything off. Your soil will eventually recover on its own, but if you're like me, you aren't waiting for that to happen. So it's time to add in those amendments. Mix them all together, taking care not to bring up any bad stuff that's still deep in the soil and wasn't reached by the process. A rake is a great tool for this step.
Once that's complete, you should have a viable garden area that's ready to grow whatever you plan on planting.
As you can gather, this isn't a process that most folks do on a whim. It's fairly involved and requires the correct material, timing, and patience. It's very effective, but it does take effort. It's something that should be done when conditions warrant, and avoided when they don't.
I'm including a few pertinent references here for those of you who would like to read a little more. The first one specifically addresses a concern many folks have with controlling the seemingly uncontrollable Bermuda grass.
Thanks for taking the time to read through this information. Hopefully, it provides enough insight to give you a good idea of the process and what to expect.
See you around the shed, and keep growing beauty, sharing knowledge, and loving nature.
Happy Gardening 🌱
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