ECHOcommunity Conversations

Weed Grass Control

Hi. I am interested in a temperate climate issue in a forest garden where we are practicing no-till…does anyone have experience or suggestions on how to contain, eradicate, and/or manage their rhizomatic grasses with mulch, solarization, etc, and what approaches do you use to clear new areas for planting without plowing/pesticides? Any thoughts would be appreciated.

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The challenge with stems/runners that grow below ground (rhizomes) or near the soil surface (stolons) is that they root at points (nodes) along the stem/runner. Tillage cuts them into smaller pieces, with each piece being able to take root, which can end up multiplying the weeds and making the problem worse. Below are just a few thoughts that come to mind.

Hand-weeding with a hoe: If you do this, you would need to try as best you can to remove all the rhizomes/stolons. Seems like a lot of work.

Solarization: With rhizomes being underground, it would be difficult to raise the temperature high enough to kill the weeds. In a forest garden, shade from the trees would also limit the effectiveness of solarization.

Mulch: This might be something you could do that doesn’t involve plowing or herbicides. I once started a garden in my backyard on a plot of ground that was initially grass. I covered the ground with pieces of cardboard left in place until the grass underneath had died. I would think the same thing could be accomplished with a thick layer of plant-based mulch. Not necessarily easy to do on a large scale but perhaps less work than hand-weeding.

Shade from the trees: Over time, as the canopy of a forest garden closes in, I would imagine the growth of underlying weeds will start to diminish.

Perhaps others have experiences with this that they could also share.

Tim

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Tim, thank you for this wonderful and very helpful insight…I
will try the boxes. In the past I have used black plastic, but
that didn’t quite kill it as I suspect some light was still
getting through, and I no longer like to use plastic.

I would say thick mulch - even a sheet mulch i.e. mulch with a barrier layer of e.g. cardboard integrated, and then ground cover planting e.g. white clover, sorrel, yarrow, ground ivy, etc. then multi-level plants. Gets rid of grass completely or leaves it so sparse control is easy. I’ve converted 150m2 large area from pasture to forest garden in this way.

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Also, you could consider a cover crop that out-competes the grass. It might not eliminate it but it would definitely weaken the grass, making hand removal easier. Here in Zambia, a local farmer testified that wherever he planted velvet beans the previous year, the grass was much thinner and he could control it easily with a hoe. I’ve also heard of red sunn hemp and teff being used for those purposes, as they also produce a thick canopy. Velvet beans and sunn hemp also have the advantage of fixing nitrogen!

Here in Tanzania majority of farmers are using chemical weed control and hand hoe weed control.
But my self I use handpulling so as feed my pigs the edible weeds.

Cover crops such as sowing desmodium seeds could be better but problem is availability of seeds.

An ECHO volunteer read your post and wanted to give feedback from his experience controlling quackgrass in his garden in Michigan in the hopes that you may find it useful. He shares his failures and learning process and considered the labor and effort required to control weedy grasses:

Our pot was originally overgrown by quackgrass. We didn’t want to use Round Up or other chemicals, so I looked for other ways to control quackgrass. I tried the following 4 methods:

  1. I sowed annual rye in the fall, cut it down the next spring, and turn it under. I cut the rye down with a scythe and turned it under with a David Bradley two wheel tractor. I did that for 3 or 4 years and then I gave up. It was brutal work and gave bad results.
  2. I started raking up all the leaves from our yard in the fall, shredding them, and then taking them to the garden and spreading them over the soil in a thick layer of mulch. The mulch stayed put through the winter and early spring. During the latter part of spring, I would rototill in the leaves and pick out stones and large pieces of quackgrass shoots. This gave better results than the rye method, but we still has quackgrass, and we had trouble with transplanted seedlings dying. I believe the decay process breaking down the leaves was producing chemicals that hurt the young garden plants. I again felt dissatisfied by this method.
  3. I started digging out quackgrass for several years through the spring, summer, and fall. I would do that now and then, here and there. It was a haphazard approach, but I saw that I was making progress against the quackgrass. I had learned how tough quackgrass was to kill, so I would burn it in a fire.
  4. Eventually, I decided the most effective approach to eradicating quackgrass was to dig the soil up in a strip maybe 8” inches wide with a spade, set the soil down on soil which hadn’t been dug and cleaned yet, and then remove every bit of quackgrass and other bad weeds. The quackgrass and weeds were burned when I had time. The cleaned soil went back to one side of the trench left from where spaded up the strips of infested soil. That way, there was always a clear line showing where I had cleaned the area and the quackgrass roots would not cross the open part of the trench. While this method takes a lot of time it is extremely effective and durable.

I help out some at another garden, run by a teacher who is a friend of ours. She and some volunteers have used a method of layering corrugated cardboard on the soil and then covering it with wood chips. It has given poor results. The quackgrass is slightly reduced but there is still a lot there. The woodchips make it very difficult to remove the quackgrass and not much easier to remove other weeds.