No-Till: Help! Grass!

I have started several garden beds with cardboard and compost (attempted lasagna / Back to Eden method), and in our climate (Hawaii), the grass is coming right through. We're heading into the rainy season, so it's only going to get worse. What would you recommend at this point? I already have some perennials and cover crops and a few other plants in the beds, but lots of empty space for grass, and even thick wood chips on top (where I have put them) don't seem to help. The grass comes up in spots all through the bed--usually with not enough root to really get hold of--and thickly around the edges of the beds.

These are the options I've thought of so far; please let me know if you have any other suggestions:

1. After watching a video from Mossy Bottom (YouTuber) where he explains different soils and when some tilling is needed before starting no-till, I'm thinking maybe I should start over and just till all the cover crops and compost into our rock-hard clay...but I doubt even that would kill the grass that's still alive underneath.  

2. Scrape all the compost off onto a tarp to reuse, pull up what's left of the cardboard, and go after the grass with a grub hoe--lots of elbow grease. Then put new cardboard, a thicker layer of compost, and wood chips down immediately (I've probably also messed up by delaying adding wood chips in the past because I'm trying to grow most things from seed and four inches of wood chips would smother the seeds).

3. David the Good's cheap and easy method--just cover the grass with another layer or two of cardboard and mulch. But I'm pretty sure I'll have to do it again within a month or two...and it doesn't work well for growing from seed (though I could just start growing in pots to transplant instead).

4. Or (and I can't believe I'm saying this), I might just have to break down and buy weed cloth.  

Whichever option I use to kill/cover the grass, maybe I should follow it by immediately and thickly planting transplants of sweet potato and/or squash? Then repeat cardboard and mulch yearly and as needed?

In addition to grass growing up through the now-soft cardboard, another problem is that we don't have defined edges to the garden beds--just small tree trunks or rocks, and the grass around the beds grows through really easily. I love the natural look of the rocks (found on our property), but am thinking we might need to remove them, dig trenches, and put plastic edging--or else just be really faithful with an edger and weeding. Sounds like from some people's experience with creeper grasses, even that might not work, though.

I want to work with God's design and maintain the joy (just watched https://www.youtube.com/watch?v=moAPtoIJy2M), but at this point all I can do is try to keep the grass from taking back over and eating up all our carefully laid compost--there's no time left for actually gardening! Suggestions? Thanks in advance!!

I've had a few no-till bed, and never had the issue of grass growing from underneath it.

I'm not an expert nor do I live in the same climate as you do, but what I think is the problem is that you have not put enough material on top of the grass. Another possibility is that this grass is growing from seeds, AKA it doesn't come from underneath. If you added soil on top of the cardboard and other materials, then it could be seeds from that soil that are germinating.

If you can provide a picture, it'll be easier to tell what is the issue.

The problem with adding just another layer, is that grass will continue growing straight through it... at least if you are using the same method as before. Since it didn't work on smothering the grass, you need to add more materials on top of it so that it can't grow, see light and start spreading again. Maybe you added one layer cardboard, one layer dry material, one layer green material and that was it. Well you should try adding one more layer of dry material, then one more of green material.

The method I've used personally is available here:

No-dig gardening

Another interesting point I didn't remember doing but is used in that article is the addition of nitrogen-rich fertilizer to the grass, so that when it's covered it can rot more easily.

Zhen said, "The grass comes up in spots all through the bed--usually with not enough root to really get hold of--and thickly around the edges of the beds.

If the grass is "with not enough root to really get hold of" then I suggest that the seeds blew in from the surrounding areas. I would keep those pulled up quickly before they get established.

"And thickly around the edges" sounds like you need to do something to keep the surrounding grass from spreading. Maybe make a path with cardboard around the planting area.

This thread from "Similar Threads" might offer some suggestions:

https://permies.com/t/155961/Brainstorm-barriers-bermudagrass#1252050

I've found since switching to no till in my garden that with grass and other tenacious weeds the very properties that make them so hard to eradicate becomes their Achilles heal. As I've added layers of mulch over the years it has composted in place. I also use a lot of radishes and turnips left to rot in place.

Unlike my old method of repeatedly tilling and the following repeated re-compacting of just the top few inches  my soil is now loose and friable to a depth I never dreamed possible. In this soil the grass and weeds easily pull out completely intact and just get dropped on top to dry out and become part of the mulch. It applies to both anything that pushes it's way through or sprouts on top.

I don't use cardboard in my garden because I don't trust the manufacture and previous use. I spent a couple years in a big box distribution center and the chemical odor that greets you when opening a semi trailer full of products packaged in cardboard was enough to turn me off of it in the vegetable garden.

The edges of beds can be a problem as the paths themselves have not had benefit of the soil improvement so the weed roots can still hold tight in there. Here I periodically shave the surface with a very sharp hoe and use a snow shovel to scrape up the weeds and small amount of soil which I toss onto the beds. I like my paths bare and hard packed, only really tough weeds like dandelions grow there. Their roots bring up nutrients from deep under the paths which get added to the beds when I scrape and toss their tops.

I agree, just keep adding more mulch. You might need to give up direct seeding for a while and stick with transplants. Four inches of mulch is nothing for grass. I'd go with 12-18" if your grass is really tenacious. You'll end up with awesome soil.z

What I've done around my beds to keep grass out is to dig up all the paths and fill them with sawdust. Grass runners that grow through the sawdust are super easy to pull out. Not much else will grow in sawdust. It's a big job though and requires a lot of sawdust. Just keeping a little two inch wide trench around your beds would help.

I understand your pain!!! Everyone with their "well you're just not doing it right", I think they just don't have the same climate or the same grass. I've been trying to do no dig in certain areas of my garden for years. And the grass just keeps coming back. I love in the PNW and the grass doesn't really go dormant and I can imagine in Hawaii it's got to be much worse.  I use cardboard because buying enough mulch to only use mulch would be $1000s of dollars. I have to spend about $500 to get a decent layer to cover the cardboard. (Do NOT tell me about "free" arborists chips, roo many people want them in my area so they aren't free.)  And we even rented a sod cutter to start without grass underneath. It grows in from the grass that we left.
And that grass! It spreads it's roots like a cancer. I have 36" high raised beds I built on an old gravel RV parking spot, the gravel is probably a foot deep. But since we moved in and stopped maintaining by spraying herbacide like the previous owners, the grass is like a golf course (only longer) and grows up into my raised beds. The roots are feet long.

Sorry I'm not really helpful. Just in the same boat. The only place I've been successful killing the grass is where I put down some weed cloth and stacked strawberry pots on top.

Hi and welcome to Permies.

I think all I can do is echo what others have said.  I grow exclusively in wood chips piled 1’ thick over the surface of the ground.  Typically I do cover the surface with a layer of cardboard which is then covered with more chips.  The cardboard helps keep the weeds down but does not completely eliminate them.  I find that what few weeds do grow are not worth the effort of weeding.  Next year those weeds will get smothered by another layer of cardboard and chips.

I don’t know if this helps you but I offer what I can.

Eric

Eric Hanson wrote:Hi and welcome to Permies.

I think all I can do is echo what others have said.  I grow exclusively in wood chips piled 1’ thick over the surface of the ground.  Typically I do cover the surface with a layer of cardboard which is then covered with more chips.  The cardboard helps keep the weeds down but does not completely eliminate them.  I find that what few weeds do grow are not worth the effort of weeding.  Next year those weeds will get smothered by another layer of cardboard and chips.

I don’t know if this helps you but I offer what I can.

Eric

I feel Eric has given you great advice.  I was going to say it would be good that your composted is 6" thick.  Eric said he uses 1' which is much better advice.

This makes it even harder for the grass to get through.

I got a bunch of grass in one of my raised beds when I added my last batch of compost. Probably grass seeds that didn't break down in the slow compost heap.

It's a bit meticulous, but just getting your hand down into the soil deep enough to find the real root, and pulling it out will also work. If your soil is loose enough this isn't that hard, just time consuming. If your soil is really packed then maybe plant a round of potatoes, daikon radish, or other big root vegetable to aerate the soil. Some daikon radishes are specifically used for this purpose and left in the ground to turn into fertilizer as opposed to harvesting.

I wish I could just heap mountains of compost on top of my raised beds, but I can't create that volume of compost and I'm averse to bringing in much from outside, mostly because of cost but also because you never know what's in it!

Boiling water is also a non-toxic herbicide if worse comes to worse, but it may not penetrate to the roots.

Hi,
I don't have this grass problem yet. Ok I have grass, but I don't have anything of value growing yet, so the grass does not bother me.
I just wanted to chime in because I listened to Dr Ingham talking about soil health, and she explained that whatever life you encourage in the soil will grow their associated plants. Adding bacterial dominated compost will just grow weeds. Any fertilizer (manures, compost from kitchen scraps) can be counted as bacterial dominated compost. Adding fungal compost will grow trees. Crops require a compost that is half fungal half bacterial. Anaerobic compost (bad smell) is just poison.

So her point is to add aerobic compost or compost tea that has a ratio funghi-bacteria of 1:1 and nothing else, along with no-till practices and maximizing photosynthesis.

Zhen Ting Ching wrote:I have started several garden beds with cardboard and compost (attempted lasagna / Back to Eden method), and in our climate (Hawaii), the grass is coming right through.

I don't see numbers anywhere. How thick was your initial compost layer? Numbers i have seen range about 10-15cm...also how often have you been weeding?
What type of carboard did you use?

Thank you all for your help and suggestions! I forgot to take photos again today, but can try to add some to this thread soon. To answer R. Han, I have used contractor's paper, and later cardboard from Amazon and similar boxes, and I try to cover it with at least 4" of compost. After reading through the posts, I'm sure that's not enough, especially since I have not been diligent (or had enough time, actually) to keep all the beds planted. My plan in the front beds was to have a thick cover crop, mow it down before it went to seed, then cover with wood chips. Well, it didn't end up being very thick--I think partly because of lack of water, and partly because birds ate a lot of the sprouts. We ended up having to weed whack instead because the mower wasn't working on some of it, so it's still kind of rough--I need to go back and hand-pull some of the cover crops before putting in the rest of the plants in the bed.

Here's what I'm thinking as a plan from here . . . please let me know if you think it will work, and any improvements to the plan:
1. Buy an edger (WORX WG896 12 Amp 7.5" Electric Lawn Edger & Trencher) and edge around all the beds. This one goes only 1-1/2" deep, but it would at least cut through the tough runners that take me forever to pull by hand once they've started matting up.
2. Buy a hand edger (the half-moon type) & go over the edges to create deeper trenches for #3 (I've got hundreds of feet of bed edging to do, so I'm thinking that using an electric edger first would make the job much more bearable.)
3.a. Install 5" terrace board around all the beds, the thickest I can find (is Master Mark brand okay? One review says it doesn't hold up when edged with an edger). Or if our budget can handle it, the "Grass Barrier" brand 10" landscape edging which supposedly works even for Bermuda grass. (As an aside, slugs and snails are a huge problem here and I'm thinking that landscape edging will just give them another place to hide, but I don't see a better option except for getting ducks, which we hope to do soon.)
3.b. Either in addition to or instead of 3.a., get the "GoldenEdge" edging blade. This makes a 1/2" wide thick edge which would possibly allow me to better grab runners that cross it, but it's not very deep.
4. Add a couple more inches of compost, 10 layers of newspaper and/or 2 layers of cardboard, and as much wood chips as possible, at least a few inches.
5. Plant transplants or seeds by creating a pocket of compost around them within the wood chips. Try sowing mustard wherever I don't have plants yet, to keep the ground covered. (Though I'm doubting this will work on top of wood chips? Mine are breaking down pretty quickly, though--they will probably be similar to my compost a few months from now.)
6. Edge as needed to keep runners out.
7. Be prompt about mowing grass to keep seeds out!
8. When grass comes through, weed it out as much as possible, then cover with paper or cardboard and more mulch.

I'd love to find a cheaper way, but with the rate at which things grow and decompose here, I'd have to layer on cardboard and wood chips every month or two if I was going to depend on that alone. Not only do I not want to use that much cardboard in my garden, but it would involve a lot more wood chips than I have access to right now, and probably take up the bulk of my gardening time. I really want to simplify so that I have time to do something besides deal with grass. Also, if I just keep piling on without any terrace board or landscape edging, I end up with a "raised" bed that has no sides to hold everything in, and the wood chips and compost quickly wash out into the grass, which is happy to grow through it.

I'm still wondering if we're going to go through all this trouble anyway, if I should just bite the bullet and scrape all the compost off onto a tarp to try to get down to the grass roots that are still underneath, and pick-axe them out. I'd hate to build a great barrier at the edges, but still have it growing up from underneath (and competing with my plants' roots) years later.

TIA!

I've never used an edger or edging, so I can't comment on that.

Do you have access to types of mulch other than wood chips? I use leaves, grass clippings, small branches, four foot tall radish plants that have gone to seed, tansy trimmings, etc. Whatever organic material I can scrounge up. If you're having trouble getting enough wood chips, maybe you have other things to use you're not considering. I don't think you need to worry about the beds turning into raised beds since organic material breaks down so quickly for you.

Pulling all the compost out, digging out the grass, then redoing the beds sounds like a huge amount of hard work. I think it would be easier to keep mulching (just mulch, not cardboard) and pulling out grass as needed. With thick (12-18") mulch, the grass does weaken, become easier to pull, and eventually gets smothered. Starting over would be a big project with no guarantee you actually get all the grass out of the bed anyway. I think mulching and weeding would be consistent work, but fairly easy work, for a year or two and would massively improve  your soil.

The only places I've been successful in getting rid of aggressive running grasses are where I've really loaded on the mulch. With thinner layers of mulch, the grass comes through quickly, I don't have time for all that weeding, and it gets established again.

Hope whatever you decide works for you!