The concept of gardening with tarps is simple. You need a tarp, some kind of weight, and time. Your goal is to kill off any grass, weeds, and seeds by creating a sunless greenhouse environment. The heat and moisture trapped beneath the tarp will cause things to grow, but the lack of light will kill off the plants as they begin to struggle when they need the light for further growth. As simple as that sounds, there are some things you might want to know in order to create your new garden space as effectively as possible.
Gardening with Tarps, Options for Weights, and Choosing What is Right For You
We tested two different kinds of tarps this year: woven poly tarps and silage tarps. The woven tarps that we used were just what we had on hand, but I did try two different kinds and preferred using one over the other. The larger woven tarp that we used was a heavy duty tarp, tightly woven, and heavier in weight. It stayed in place better and was not prone to having aggressive tap-root weeds push through the weaving. They are also built to handle more sun exposure which means it didn’t feel the least bit brittle when I was finished.
As for the silage tarp, we ordered a new 40’x100′, 6 mil., two-sided tarp. One side is black, the other is white. Farmers typically store their silage with the white side of the tarp facing up, but for our purposes, we needed to be able to use the black side. We ordered the thicker tarp because we needed to be sure it would be strong enough to hold up to a number of different factors (weather/nature, and children). You can order smaller silage tarps if you didn’t want to prepare such a large area, and you can also order larger tarps as well, though they are more difficult to work with and might require you to have some machinery to move them around. The 40’x100′ tarp was able to be handled by the three older kids (9,7, and 6) and myself. We couldn’t have done that with the 40’x200′ tarp, and I’m not sure we could have done it with Scott, either. It would have taken a few grown adults.
Whatever you use, woven tarps or silage tarps, you want it to be dark! The dark helps germination of seeds begin and mimics what nature does for starting seeds, but it blocks out the light which is what keeps plants growing once they have germinated. You’ll notice your tarp start to push up a bit after awhile from the plants beginning to grow underneath, but it will quickly sink back down if your tarp is dark.
As for weights, on the woven tarps we were able to be a little less concerned with what we used. We used logs and wooden fence posts as weights and it worked just fine. But for the silage tarp we were more concerned about our weights causing the tarp to tear. You could us a wide variety of objects to weigh down a woven tarp, but with a silage tarp your options are limited. We ended up choosing used tires as our weights, but another option I looked into was sand bags.
Woven tarps or silage tarps, logs or rocks or odd objects versus tires or sand bags, it’s really going to depend on you and what your situation is. A silage tarp is a good investment if you are looking to have some kind of farming operation… something where you need large areas of land prepared for planting and you plan to use it over and over again. If you know some of your local farmers, you might be able to ask them if you can have or purchase their old silage tarps (because they will eventually want to get rid of them and replace them with newer tarps) though you might need to cut them into smaller sections or repair them with special tape. It’s what we would have done if we had the opportunity, but ordering one was a better option. As for tires vs. sand bags, that’s going to depend on you as well. If you are planning to use your tarp over and over, it makes sense to have a weight that will hold up over time. Sand bags are nice, but the bags themselves tend to break eventually, and they cost money, both to fill and to purchase the bags themselves. A ruptured bag means more work and money for the cost of a replacement.
The woven tarps make more sense if you are looking to prepare a smaller area. You can use what you have around your home to weigh the tarp down and there’s no need to hang onto tires or sandbags that you’d only use once (because in all likelihood, you are probably only preparing smaller areas one time). I wouldn’t want to use smaller tarps over and over for these purposes because they will begin to deteriorate at some point, and they also aren’t rated for storing food. The silage tarps are BPA free, but I can’t vouch for the poly tarps. One season of using the woven tarp won’t cause a bunch of decay, but repeated use of it will. (Using rolls of plastic like what is used for painting or construction is an option, but not a great one. Clear plastic will only act as a greenhouse and won’t be effective. Black plastic works, but it will break down and it’s not BPA free.)
Time and Timing
Time and timing are everything when it comes to effectively tarping a new planting area. You need a minimum of 6 weeks for it to work, but 12 weeks is supposed to be optimal. I’m starting to think closer to the 3-4 month range would be best. The longer your tarp is down, the more effective it will be. But the longest amount of time it is recommended to leave a tarp down is from fall to spring. Too long on the ground and it will start to kill off the organisms that live in the soil. A full year would be okay, but is not supposed ideal.
That being said, the length of time your tarp stays down is really going to be dependent on when you put the tarp down to begin with and the weather in your area. If you put your tarp down in early spring, before the grass has begun to green, it doesn’t need a lot of time to work it’s magic. The grass is dormant which means it is easier to kill off everything, the weeds are dead, and the seeds are ready to germinate. If you put your tarp down after the grass has greened and begun to grow again, the tarp has more work to do. That being said, the heat of summer makes the tarp more effective in some ways because the heat will cause the plants to die off more readily. In spring, however, the skies tend to be cloudy and the weather cool, which means it could take longer than you expect.
Either way, you are really best off giving your tarp 10-12 weeks to do its thing. I was forced to remove my tarps before 10 weeks in some areas, and where I was, it definitely wasn’t as effective, though it did make a really big difference. I currently have the silage tarp down in a “new” area (it’s been over a month now, I think), and it will stay there until the fall. I should see much better results in that area when the tarp is removed.
Preparations After Tarping
While the length of time you keep your tarp down is the biggest factor of success, there are other things that will make it more or less successful after the tarp is removed. The first thing you need to remember is that (in the words of Justin Rhodes) “Mother Nature doesn’t like to be naked!” Even if you effectively tarp the area, if you don’t do something to cover this newly prepared area, nature will!
You know that saying “Only two things in life are certain: Death and Taxes”? Well that should end in “Death, Taxes, and Weeds.” Regardless of what gardening method you use, weeds are a certainty. Even the methods that help you keep weeds suppressed don’t guarantee you won’t have weeds. One of the reasons I like the Back to Eden method so much is because while it doesn’t prevent weeds, it makes weeding SOOOO much easier. Some people till their weeds, some people spray them, some pull them, some hoe them. But if you want your plants to be successful, you need to keep the weeds in check.
We’re organic gardeners, so spraying isn’t an option. On top of that, I’m known for killing equipment and besides that, I have my reasons for not liking tilling so tilling is out of the question. That leaves me with two choices: mulching or cover crops. The point is, get that soil covered. You want to beat nature to the punch. If you can start your seeds immediately before removing your tarp (or even if you remove your tarp a couple of days ahead of when you really want it removed, plant, and put the tarp back) great. You want to be the first to plant your seeds. Not the birds, not the wind, not the squirrels. You.
But there’s one step in between removing your tarp and putting on some form of ground cover. First, you need to clear your soil. The plants are dead, but you have a task to complete. Most of what I had read or heard about talked about raking. Rake off the debris, and rake to loosen the top soil for planting. Raking wasn’t going to work for me. Another thing I had heard about was weed burning. But another method, unrelated to tarping that I had heard about for preparing a garden was to use chickens. We did a little of both.
Originally, my intention was to use the chickens to till all of the areas that we tarped, but the fire wrecked those plans. We used our remaining chickens to prepare the smaller area, but since we had no chicks to move to the field, we were left with little choice. We decided to use a weed burner to prepare the pumpkin patch, but part way into burning off the debris, the hose stopped working. We weren’t able to fix it immediately and were up against a deadline and crunched for time. Scott wasn’t able to work on fixing the hose for the burner and I didn’t have time to wait, so I decided to throw down the cover crop of red clover right away and just skip the weed burning. It was that or let the weeds take over. The weed burning was very effective at finishing clearing the soil for planting, and I’d highly recommend it. There is most definitely a difference between that area of the patch and the areas that were not burned.
As for the chickens doing work, I tried that two different ways. Both were effective, but one more so than the other. I’ll cover that in more detail in another post soon. The chickens loosened the top layer of soil for me, and ate away any weeds that hadn’t died off completely.
No matter how you look at it, you do not need a weed burner or chickens to prepare your soil. You can do a rake, but it might not be very effective and you might find it tedious. Regardless of how you prepare it, be ready to have some kind of covering on your soil when you are done. And the sooner you can get your seeds or your starts into the ground, the better!
Now, our tarping project didn’t go perfectly. We had some issues along the way, and there are some things we learned. As I said, the amount of time you keep your tarp down is going to be the biggest factor of success. If you can keep it down for 12 weeks, do it. If you don’t, expect to have grass re-grown and weeds with deep tap roots wanting to stick around.
Whether or not you do anything to prepare your soil before planting makes a big difference too. If you don’t do anything and your tarp has been down long enough, you might be just fine, but if your tarps didn’t have enough time to work their magic, then you need something else to help you finish the job. Weed burning or chickens or a tiller could all do the trick, and even raking and some hand weeding will work fine. And if you don’t put down a ground cover, you can expect to have the weeds find you, fast and furiously. The longer you wait to put down a ground cover or to do some kind of preparations (such as chickens or weed burning) the less effective your tarping will be.
Remember to plant as soon as possible after removing your tarp. If you don’t, nature will, and you won’t be happy with the results. And also remember that all gardens have weeds. Period. Even if the tarp does its job perfectly and you do everything perfectly, you will still have weeds. The goal of tarping is not to not have weeds, but rather to prepare a new garden bed without the use of equipment and if one of the other myriad of ways to prepare a garden bed aren’t appropriate for you.
If you want to learn more about using tarps for gardening, you should really look up Curtis Stone on YouTube and look up JM Fortier online. Both use tarps in one way or another to prepare their market gardens and both have really helpful information out there on how to tarp.
I’d love to hear from you. Have you tarped to create a new garden bed before? If so, what did your experience look like and what did you learn? Let’s share our knowledge and make the world a smarter place!
Wait! One last thing before you go! I’m teaming up with Baker Creek along with some of my fellow bloggers to have another Baker Creek Heirloom Seed Giveaway! We’re working to put together a collection of seeds, perfect for planting in your fall garden! (Yes, that’s a lot of exclamation marks, but I’m so excited for you!!!) You’ll have to keep your eyes peeled for this in the next couple of weeks 🙂