keeping roots out of a garden bed

[paradajky]

Hi:

We dug out one of the garden beds, 10x18 ft, about 1.5-2ft deep yesterday. It was full of roots from the surrounding trees (fruit, pepper, palm, various groundcover, etc). We will not remove the trees, and don't have any better places for a bed at this time.

The bed is on a slope, and its bottom follows the angle, it does not cut into the hill like a terrace.

The bed was originally lined with the cheapest landscape fabric, and the gardener who did it overlapped each sheet by maybe an inch or two.

We are thinking of relining it better this time, but not sure whether to use a higher quality landscape fabric or a plastic sheet (6 mil is available locally; 14 mil pond liner is as well, but it is almost 8 times more expensive per sq ft).


Benefits of the fabric are that it is breathable to some degree and the quality one looks like it would keep roots out and last a while (we made grow bags with this stuff). However, we're concerned the roots will find their ways through the overlap, so possibly we could glue the overlap or do something like a 50% overlap of each sheet. Seems wasteful.

Therefore we're looking at the plastic sheeting, and the benefit is that it's large enough to cover the entire bed in one piece. I've read it's bad to use this as water can pool up. Is this a concern if we are on a slope? We could put a drainage pipe with holes that runs parallel at the lower edge and provides an exit for the water, but I'm not so sure that's necessary since the walls of the bed are porous.

If we can go with plastic sheeting, would the 6 mil be sufficient? The pond liners are either all pvc or ldpe reinforced with pvc, and I'm just more comfortable using ldpe with the constant contact to vegetables.

Thanks for sharing your thoughts.

[kurt]

We use this from Amazon.Two layers and turned up and stainless steel staples.Our first attempt failed ,the mango roots,lychee roots crawled on top of fabric and took over.Have fun.
https://www.thespruce.com/best-lands...hoCFdYQAvD_BwE

[paradajky]

Hmmm, interesting, doubling up the layers, I was wondering about that. Your link gives a variety of options, which one in particular are you using?


Most of the weed barrier cloths are sold in 3 or 4 foot width pieces, which would require overlapping. If that's what you did, how much did you overlap each of your sheets?


In the spruce link, there is one that is used for soil erosion and is a 12.5ftx60ft, which could easily be laid down without worrying about the gaps. But according to the article, it's not very permeable so hmmm.

[PaulF]

A few thoughts: When we first moved to our present location the garden space in our yard was a weed and brush overgrown area with several,, no, a bunch of trees of all sizes. The brush we cleared along with the weeds and the three or four larger trees we cut down and had the stumps ground.

The area had never been tilled, so was virgin land made up of Loess soil (also called sugar clay) and was nearly devoid of organics. The first year after tilling the soil, it produced mostly native weeds and brush which was nature trying to reclaim what had been there for aeons.

The second year we put down landscape fabric as a weed barrier and grass clippings over that as a mulch. My previous attempt (in a different location) at using plastic taught me about water pooling and lack of air flow into the soil. The fabric we used was not the heaviest available but a middle grade air and water permeable. It worked well but there were certain problems for this particular garden space.

As stated we had a lack of organics and every year we had to add as much as possible to bring the soil into good shape. That meant rolling up the fabric, tilling in the clippings, extra organics in the form of compost both homemade and purchased. Also according to professional soil test results added nutrients needed to be incorporated. For us it was primarily elemental sulphur and nitrogen. I even tried some cover crops ( which in this area was not very successful).

The fabric lasted only two or three years before it disintegrated. The labor to lay down and then later remove the fabric proved to be too much for me. Since then I have gone from fabric and grass or straw to newspaper as the weed barrier and straw as the mulch. At the end of the season it all gets tilled into the soil. After eighteen years the organics are pretty much in line and the labor is a lot less.

We still have native weeds but not many. We still have roots poking up every once in a while but not many. A few little trees show up but are easily pulled. I get end rolls of newsprint from the local newspaper for free. These are 32 inches wide and up to fifty feet long so rolling them out is easy...I double or triple layer the paper. No need for staples since I put straw on the paper as it goes on the soil (picking a still day works best). When it is time to plant just move the straw and punch a hole in the paper.

Over the past 50 years I have tried almost every method of mulching and weed barrier in the garden and the above works for me. Not being familiar with southern California tree roots my experience may not be of much help, but we battle boxelder, honey locust, black walnut, cottonwood, honeysuckle, virginia creeper, greenbrier and sumac among many others in our gardens and landscape. If paper and straw can hold these at bay why not yours.

Good luck and good gardening and most of all...have fun!

[paradajky]

Hey Paul, if I read correctly, you till in last year's cardboard/clippings/straw, then spread newspaper, clippings, straw atop that, and plant into it. The roots just grow as they may.



This does seem like a good way to do it, but I'm not sure how that would work in my case, the amount of roots entering the bed was considerable after only 18 months, it was completely overtaken. All our veges began fine and slowed to a crawl about 5-6 weeks in no matter how much organics and fertilizer we added. We have this problem in two other beds on the property, but they are flat, not on a slope like this one (I shared pictures of these beds in another thread, this new one came as a complete surprise because there was a cheap weedbarrier placed underneath).



I'll take and share a picture of what we dug out later today.

[PaulF]

It almost sounds like you have so many roots they are sucking up all the nutrients. That would be a big problem and would be more than my experience could help with.