A New WayTo Secure Plastic MulchWith Raised Garden Beds

Dateline: 27 April 2015
click on pictures to see enlarged views

In my previous blog post, titled Step-By-Step Raised Garden Beds, I showed my simple way of making raised garden beds. The technique I use is nothing new, but the blog post shows a systematic approach to the task. The end result (pictured above) renders an orderly, visually pleasing, and practical garden bed. But making the beds is only part of the systematic raised bed approach I'm developing in my garden. There is also the added aspect of plastic mulch for weed suppression.

As many readers of this blog know, last year was my first gardening year in which I used black plastic mulch (Click Here  and Here for last year's blog posts on the subject). Black plastic is certainly not anything new in the world of gardening, but it was new to me. I've been gardening since I was around 16 years old (I'm 57 now) and I refused to use plastic all that time, primarily because it's not "organic." 

I don't know if I've compromised in my "organic" convictions, or just gotten smarter. Probably a little of both. The fact is, last year's plastic mulch trial run was a great success. I had one of the nicest looking, most productive, and downright satisfying gardens I've ever had.

I used three different techniques for securing plastic sheeting from blowing away last year. In This Blog Post I showed how the edges can be buried, and how to make "staples" to hold down any edges that are not buried. I used both techniques for securing permanent plastic mulch, which is to say, plastic that will remain in place for it's 8 to 12 year lifespan. Thus far, both techniques have worked very well.

For securing "temporary" sheets of plastic in walkways between my garden beds, and for holding occultation covers over the top of beds, last year I used tire sidewalls. I have lots of tire sidewalls and have used them for many years for various purposes in my garden (they are discussed on pages 45-48 in my Planet Whizbang Idea Book For Gardeners).

The tire-sidewalls-as-plastic-holders worked pretty well, but, when used to secure plastic in the walkways between beds, they presented something of an obstacle to walking. And, as many sidewalls as I have, they are not enough to handle the greater number of raised beds I'm now making in my garden.

So, another idea for securing the plastic mulch is needed, and I found the needed idea right in my own Planet Whizbang Idea Book For Gardeners. As I say in the introduction to the book, "... it so happens that ideas beget more ideas, and even the best of ideas can often be improved on." Or, in this instance, a good idea can be appropriated and applied to another purpose. 

On page 71 of my book I tell about "Mark Albert's Caterpillar Cloche System." Mark is a smart guy and he devised a way to simply and efficiently secure plastic or floating row covers over hoops. His system involves sturdy stakes, polypropylene baling twine (super strong and no stretch), and.... clothespins. Why can't the same brilliant system for holding row covers over hoops be used to hold plastic sheeting over raised beds and in the walkways between beds? I can't think of a reason why not.

By way of review, the plastic I'm using for reusable (8-12 year lifespan) mulch covers in my garden is Dewitt Sunbelt woven ground cover (3.2 oz). I purchased 4' wide and 3' wide rolls last year. With my 30" wide beds and 18" wide walkways, and the hold-down system I'm about to show you, the 3' wide rolls will work. Here's what the product looks like...

As you can see, the plastic needs to be heat sealed on the ends (as on the left side in the picture) or it will unravel (as seen on the right side). My standard length of garden bed is 16', so I have cut 17' lengths of the plastic.

To secure the plastic, I repositioned the polypropylene strings that outline each bed down tight to the ground. Then I used clothespins to secure the plastic to the string, as this next picture shows...

At one end of the garden beds, I tucked the plastic under the sheet metal walkway...

At the other end of the bed, I used a rock to weight the plastic down...

This next picture shows plastic secured in the walkways between the three example raised beds...

The same string lines and clothespins can be used to hold an occultation cover over the beds. Or they can be used to hold a sheet of clear plastic over the beds to encourage weed seed germination.... 

Using clear plastic for this purpose is a new idea for me. The plastic is 4mil at 3' wide, and it is common plastic. I'm curious to see how well it holds up and how many years of use I can get from it.

After the weed seeds have sprouted up under the plastic, I will put an occultation cover over the bed to kill the weeds. Then, once that is done, I'll plant into the bed without disturbing the soil. This should significantly reduce the number of weeds that sprout in the planted bed.

I secured the clear plastic over the bed on the end by tying a short piece of string from stake to stake and using clothespins to hold it...

The big question with this plastic hold-down system is... will it hold up to heavy winds? I have a somewhat sheltered garden (which is what you want with a garden space) but the day after I put the plastic in these garden beds we had some very high winds. They were enough to peel back a couple of sheets of the metal used in my walkway, and that was a first. But the plastic secured with the string lines and clothespins showed no ill effects at all.

Mark Albert's system for holding row cover onto hoops proved itself to me the first time I used it. I stood in my kitchen and watched a thunderstorm with driving wind and rain pummel the hooped cloches for half an hour. I fully expected them to give way, but they didn't. This odd little idea really works. But, as it applies to plastic mulch covers, it is still an idea I'm testing.

Speaking of testing garden ideas, this next view, taken from behind my row of raspberry canes, shows sections of my garden under large sheets of plastic (in the background). That is my Gardening Without Cultivation experiment from last year. The idea worked very well last year, but I'm still evaluating Tom Doyle's approach to gardening.

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Click Here to go to Part 3 of this garden bed how-to series.