Solarizing Garden Beds

Dateline: 19 February 2016 AD

The experiment in last year's garden.
(click picture for larger view)

Last year I posted a photo essay to this blog explaining how I make raised beds in my garden (Click Here For Details). Then I posted another photo essay showing a new technique for holding sheets of plastic mulch and ground cover fabric on the beds and between the rows (Click Here For Details). I can report that my idea for securing the sheet materials worked very well last year. The only problem being that in a big garden, a lot of clothespins are needed. But I'm working on a less expensive, longer lasting alternative to using the clothespins, and hope to report on that breakthrough soon.

For now, I want to follow up on the idea of solarizing a garden bed using clear plastic. That was something I tried with two garden beds last year, as you can see in the above picture, and in this next picture...

The soil solarizing concept is very simple. You prepare the soil, layer a sheet of common clear plastic over the top, and let it be for a month or so. Heat from the sun "cooks" the soil under the plastic. Weed seeds are killed, pathogens are killed, fertility is released. There are lots of internet articles on the subject (with more specific information). Here is one: Soil Solarization

One drawback to soil solarization is that it takes time. If you need the bed for planting first thing in the spring, you don't have time to solarize the soil. But my garden is big enough that I have room and time to solariaze. In the picture above, my plan was to let those two beds solarize until early July and then plant my fall crop of Four-Day Carrots in them. And that's what I did, but with only one bed. I never planted the other bed to carrots. I wish I did, as our stored carrot supply here in February is getting low.

Anyway, here is a picture of those two solarizing beds later in the season...

If you click on the picture and take a closer look you'll see that some weeds have grown under the clear plastic around the edges. But nothing at all has grown over most of the bed. 

In this next picture I have removed the plastic prior to planting my carrots (in July)...

As you can see, most of the bed is well solarized, except for around the edges. But the edge weeds are lush and easily pulled...

The pulled weeds went into a compost pile. I then put a thin plastic mulch cover over the bed, and proceeded with my Four-Day carrot planting. I did not disturb the solarized soil beyond the disturbance that happened when pulling the edge weeds.

In these next two pictures you can see the carrot tri-plantings getting off to a good start. I do not recall pulling a single weed out of that bed for the whole carrot-growing season. Between the solarization and black plastic mulch, weeds were simply not a problem.

And here are a couple pictures of the carrots that grew in that garden bed...

In the final analysis, I am persuaded that solarizing a garden bed is a good and worthwhile thing to do. I will definitely be solarizing next year's carrot beds (the late-planted beds) and any other garden beds that lend themselves to this practice.

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More information about my carrot-growing strategy can be found in the chapters titled My System For Growing Easy Carrots and Tri-Growing Carrots (a curiously fun idea), which are in The Planet Whizbang Idea Book For Gardeners. Read those chapters, and watch the four, Four-Day Carrots videos on YouTube, and you will know everything I know (thus far) about successfully growing garden carrots.