Need to convert pasture to garden? Or any weedy or grassy area? Here’s how we are doing it:
We are in the process of converting roughly 1750 square feet of pasture area into our future garden. When I was doing some research on how to do this, some of the most common themes I found were to till, till, till, use Roundup, or both. We try to follow organic gardening methods, so Roundup is not an option. We are trying to start our farmstead on a budget, so we cannot afford to buy or rent a tractor, it is also not cost effective for such a small area. We could possibly rent a walk-behind smaller tiller, but we also want to try to follow no-till-garden practices. And even if we tilled, the grass and weed seeds would still be present in the soil, and presumably continue germinating and growing in the future; it would only be a quick fix.
I continued looking for alternative organic methods to convert our pasture into garden. The biggest hurdle was trying to figure out how to keep the grass seed from growing season after season, which would choke out our future crops, and would be impossible to hand-weed. Then I stumbled upon an article written by Rodale’s Organic Life, which discussed using the sun to kill weed seeds and other garden headaches. The article was about the process most commonly called Soil Solarization. The process seemed to make sense and looked easy enough, so I did some more research and we gave it a try!
Here is how were doing it:
Our pasture grass is over a foot tall, so the first weekend we spent clearing the grass with a weed-whip/weed-whacker. We had to go over the area a few times, getting lower and lower each time. We then followed with a regular leaf rake to get all the cut grass and weeds out of the garden area. Lastly, we used a dirt rake to get the remaining grass and some surface roots, rocks and other debris cleared out. We also used the dirt rake to help even out the surface; fortunately this area is already pretty flat.
The next step is to wet the soil. Ideally you want to irrigate the soil down to 12 inches. The moisture in the soil helps conduct heat during the solarization process. We bought some 2mil clear painter’s plastic from the hardware store and laid that down on the ground quickly after we irrigated. Then we shoveled dirt mounds on the edges of the plastic to create somewhat of a seal to keep the heat and moisture in, and also to prevent the plastic from kicking up in the wind. And that’s about it! Super easy!
How it works:
The moisture helps germinate any weed seeds that may be in the soil. With the sun’s heat cooking the soil underneath the plastic (to temperatures over 120°) these germinated weed seeds are then killed along with any plant matter. This heating also kills most organisms living in the soil, which is good and bad. It’s bad because it will also kill some good organisms, but fortunately they can multiple quickly in the soil once the plastic is removed. It is also believed that most of the earthworms can burrow down deeper into the soils so that the heat doesn’t harm them. The tradeoff for the negatives is that the heat will kill all the bad organisms and weed seeds living in the soil. It will also help break down any organic matter quickly, much like a compost bin on steroids. Some people will even add chicken manure or other compostable items that take time to break down on top of the soil before they lay the plastic down. They have 4-6 weeks to wait anyways, and the heat from the process helps break down the organic matter faster as well.
In order to be successful at solarizing your soil, it needs to be done in the hottest time of the year, so preferably in the summer. We had a couple weeks of cooler and cloudy weather, so we had to wait until the clouds cleared and temperatures warmed up. Fortunately, the weather changed quickly and we received temperatures around 100° so far for the first week of the solarization. A couple days in, I touched the plastic and it was extremely hot, I am excited to see the results in a few more weeks. Since we live in southern California, and the weather has been, and is predicted to stay really warm the next few weeks, we will probably lift the plastic off at about the 4 week mark. The normal range is between 4-8 weeks depending on your needs and climate. Make sure not to plant anything in the garden right away after taking off the plastic, the soil needs a little time to cool down first.
I will post another update in a couple weeks once we lift the plastic and then again after a few months of cultivating the garden; that way we can critique this method and inform you of the results.