Toby Hemenway's Bombproof Sheetmulch

Hello Permies. This is my first post. Nice to meet you all.

My cousin and I started our first little Permaculture project last spring. We wanted to do Toby Hemenway's bombproof sheetmulch and grow a garden. We're both new gardeners for the most part. So we began:

First we laid cardboard:


Covered it with dirt:




Then added straw:


We did all the layers, just as in Toby Hemenway's book.


Here was our design layout. We tried to do companion planting:


Then we encountered a few problems. The first is that we weren't sure how to plant into the sheet mulch. I had my cousin add a bit of soil with each seed into a small hole he opened up with a stick. None of the seeds we planted saw the light of day.

The second was that the straw we got was full of seeds. So the straw seed went crazy over our whole garden:


I had my cousin crop it all in place with a weed-wacker. I don't think he cut it until after the straw took seed, but it's hard to say:


We've been trying to figure out how to kill or out-compete the straw seed so that we can grow in this coming year. We've thought about laying plastic during the hot months to "sterilize" the whole garden, but we'd lose a year and I'd rather not use plastic if we don't have to. Perhaps there's a cover crop we could use to out-compete it? That and hacking it before it seeds a second year (how long can straw seeds germinate?).

So my two questions to the permaculture community are:

1.) How do we plant into sheet mulch?
2.) How can we kill/out-compete the straw seed?

Any other suggestions for our gardening setup?

Hello Jesse and welcome to Permies!

I added a couple of flags to your question to see if we can get more people checking it out. Practice often brings out problems with theory, but Gaia's garden is such a mega-hit in the Permaculture world, surely many people have tried Toby's recipe before you.

My own experience with using straw as mulch gave results similar to yours, but since my use was confined to a 8'x4' raised bed, hand weeding was feasible and that is indeed how I dealt with the many grass plants that sprang up.

I don't like the idea of trying to sterilize the seeds in place with plastic, and not just because I like to avoid plastic. You'll kill a lot of the beneficial organisms you are trying to invite into your garden/field that way.

I hope we see some good suggestions here soon.

You'll kill a lot of the beneficial organisms you are trying to invite into your garden/field that way.

I agree. To kill off the seeds, you need to heat the soil to temperatures that will also kill much of your "Soil Food Web". The worms will migrate deep enough to (hopefully) survive, but the micro organisms (bacteria/fungi/etc.) move too slowly to retreat to a safe depth.

It is much easier to weed out what you don't want growing than it is to replace the micro organisms that would perish in the 'solarization' of the bed.

Newly built soil has a wonderful tilth which makes weeding effortless - especially if you do it right after a rain, while the soil is still damp.

heya... make best of it. i mean, now you ve got added organic material and root matter. you ll probably get added fertility by that. so be happy and deal wisely with it.

i d keep the weeds low and then plant the potatoes first. they ll shade out much of the weeds. and then just go step by step. clear a spot. plant/sow MULCH (alot). plant/sow densely to shade out the weeds. and just go on.

i d bury some kitchen scraps or other organic material in some places from time to time. to help the worms. just put it under the straw and/or cover it wit a bit of earth. composting in place.

grow some start. like cabbage

plant some huge thingies like squash and zuchinis. huge leaves

plant some high/permanent thingies .... berries

plant your sunflowers and corn. they ll grow higher then the grass. mulch under them.

what i d do: make small (1-2 inches) trenches. fill with earth and grow beans and peas. so you ve got rows. mulch left and right from these rows and let the beans/peas grow to the sides. maybe grow some upwards on stalks/trellises/fencing

get some nasturtium

make small clearings for smaller veggies. just try, what competes well with the grass. WATCH. if you veggies seem to get outcompeteted by the weeds, help them by weeding and/or mulching.

when you can t plant some areas now, get a cover crop.



just fill the garden with good stuff. shade out the grass. fill them empty spaces with good stuff. or weeds will fill them. just help your plants to get a good start (doing starts inside or clearing spots form them, mulching, a bit weeding when needed).
chop the weeds, when needed. mulch alot


good luck and blessings.

If you like pork, as a last resort you've always got the option to pig-nuke it. Pen the garden off for a few months while you raise a weaner pig or two to slaughter in there. There shall be no rhizomes left from the grass, but the soil food web shouldn't be overly damaged [in fact it will likely be feasting on the pig waste.]

Just goes to show... It pays to know the origin (i.e. know the farmer) of EVERYTHING. Buy from someone who you trust and who you can ask specific questions about the product.

To make my raised beds, I got loads of hay and straw. The hay was free from a farmer I know. He warned me, "Watch out, it might have some seeds -- I just went in and mowed down a couple of fields and here the stuff is, I tried to do it at the right time to avoid seeds but no guarantees." My leftover hay shows no signs of sprouting anything. First class stuff. Great choice.

The straw, however, I bought from an unknown neighbor of said farmer. The stuff I had read previously said you shouldn't have many problems with seeds in straw, they problem was usually the hay, so I was not worried. My friend told me, "It should probably be OK." And of course it's loaded with all kinds of grass and weed seeds which have been busy sprouting up through my raised beds all season. Not really a problem as I'm dealing with 20m2 of raised beds, not a field-full.

I had the option of buying both hay and straw from a nice conscientious hippie organic farmer about 400 miles away. He knew what he was doing and guaranteed me no seeds, and I believe him. I chose to avoid all those transportation miles and take advantage of the free hay locally and didn't think much about the straw. Just goes to show. I'm not really dissatisfied with my choice though, these things happen and they're not too hard to deal with. Especially with loose, new soil, weeding can get a lot worse than that.

Besides whacking, weeding and mulching, I second the idea of nasturtiums. They are great, totally edible, beautiful ground cover and they seem to smother out *anything* in their path with ease. Lots of good ideas above here for things you can grow this season though. The pig nuking idea is hilarious and of course a time-tested permaculture technique.

Alright. Thank you for all these replies. I am starting to formulate a strategy in my mind. Let me rephrase:

Pig nuking is a last resort method that will work well.

Hand weeding should be easy in new soil. We can plant Nasturtium to out-compete the grass over areas we can't manage this coming year. Over the whole garden if necessary.

To plant, we should add some good soil in little pockets or rows, along with the seed, then mulch around it. Big leafed vegetables like squash and potatoes will help us shade out the grasses coming in. Start with potatoes first. Smaller herbs and vegetables may be more difficult to deal with, may require more hand weeding, and a careful eye to see what's growing and what isn't.

We should add compost pockets at intervals into the garden to aid the worm community.

Questions:

What should I be adding as new mulch?
Is new mulch even necessary with all the bio-mass we have in this garden?
Does it ever work to just drop a seed into what's already there, without adding new soil/mulch?
The neighbor has a big supply of mature raspberry plants. How should we transplant them?

Thanks everyone!!!

Jesse and Kyle

Way to go! His "Bombproof" is quite an undertaking with an extensive ingredient list. You'll be rewarded for many years to come having started this way. Tony's answers to your questions are: "it's best to cover any seed containing mulches with a couple of inches of straw, soil, bark, of other weed-free material. What fee weeds appear are easily pulled from the loose soil. To stop futurd weeds, just like on more mulch." And for planting into: "start seeds by making tiny trenches about three inches deep, filling them with soil or compost, and seeding these. Seedlings and starts should also go into small soil pockets about three times the size of the plant's root mass." The suggestion of planting nasturtium is a good one, just remember to use something like a fingernail file to take off some of the hard seed coating before planting. Good luck and happy gardening!

You might look into Colin Seis and his 'pasturecropping technique for some clues. To the best of my understanding he grows annual crops in his fields-or paddocks as they say downunder after the grass has been grazed.
Colin now sows commercial crops into the dominant
pasture by direct drilling to minimise soil disturbance.
Sheep are used to prepare paddocks to pasture crop and
crops are sown, usually with no herbicide and 70% less
fertiliser than conventional methods. Only relatively small
amounts of liquid organic fertiliser are added at the time of
sowing, using the same machine, so that tractor costs and
soil compaction are minimised.

Jesse Fister wrote:Alright. Thank you for all these replies. I am starting to formulate a strategy in my mind. Let me rephrase:

Pig nuking is a last resort method that will work well.

Hand weeding should be easy in new soil. We can plant Nasturtium to out-compete the grass over areas we can't manage this coming year. Over the whole garden if necessary.

To plant, we should add some good soil in little pockets or rows, along with the seed, then mulch around it. Big leafed vegetables like squash and potatoes will help us shade out the grasses coming in. Start with potatoes first. Smaller herbs and vegetables may be more difficult to deal with, may require more hand weeding, and a careful eye to see what's growing and what isn't.

We should add compost pockets at intervals into the garden to aid the worm community.

Questions:

What should I be adding as new mulch?
Is new mulch even necessary with all the bio-mass we have in this garden?
Does it ever work to just drop a seed into what's already there, without adding new soil/mulch?
The neighbor has a big supply of mature raspberry plants. How should we transplant them?

Thanks everyone!!!

Jesse and Kyle

I hope someone more expert than I can chime in because I only know what I read, I'm also pretty much a permie newbie. But I just wanted to suggest, it might be better and less destructive to chicken-nuke it than to pig nuke it. And maybe as a first choice rather than a last one. If you want seeds gone from your soil and fertilizer applied, nice and high in phosphorus too, chickens (from what I read) are your ticket. Of course I suppose you'd want to weed whack again first if the grass has gotten too high again. Smart old-timer permies: Do you think that would do the trick?

As far as what mulch to cover with later, I would say a thick one (8" or so) and one with no seeds, other than those criteria use whatever you have easy access to.

Remember the mulch for your purposes is mainly to make damn sure that grass doesn't get out of hand. It's not because you don't have topsoil. Of course it also has the advantages of retaining moisture and building even more topsoil over time, but who can complain about that? This is permaculture, after all.

As far as planting into all of this, seeds or raspberries or whatever, I'll let other permies with more jungle smarts answer that.

Edit: Oops, PS: I've never had a problem with plopping nasturtium seeds into the ground just as they are with no preparation. They can take a while to germinate and get going, but once they do they can eat Tokyo.

Pig Nuke vs Chicken Nuke depends on your goals.

Chickens are pretty hard on the system, shredding the carbon into tiny bits and devouring the larger active components of the soil food web.

That's not to say Chickens aren't a viable option, but they are a more intense option.

Sheet mulching is my thing. Been doing it now close to 40 years, (with some gaps when I was at sea as a marine engineer) Weeds don't bother me at all. Easy solutions.

To fix what you have there, 6 layers of newspaper covered with grass clippings ~3in. just lay down the news paper in 6 sheets thick, and cover the whole thing with grass clippings 3 inches thick. Or alternatively you can buy a commercial sized roll of paper or rollable cardboard made for packing, covered with grass clippings. Both are available recycled. BTW strictly speaking what you made there is a lasagna bed more than actual sheet mulching. Sheet mulching is a sheet of paper or cardboard covered with mulch. You plant THROUGH the weed barrier into the soil underneath. Lasagna beds are layers of multiple materials including compost and soil and mulch etc.... and you plant INTO a lasagna bed, not penetrating the bottom weed barrier. The difference is subtle, and many permaculturists interchange the terminology, but I am old school (first mulched bed at age 8 over 45 years ago, first sheet mulched bed at age 14 if I remember correctly, and first lasagna, called layered beds back then, by 17 or 18 ) and I think the proper terms for each avoids confusion.

Next time you use hay or straw sheet mulching and get grass sprouting, simply flip the straw upside down. This will kill the baby grasses before they can sink roots deep. But that is too late for you now. That's why I suggested grass clippings. There are other materials you can use, but for beginners this works well.

Each variation has it's tricks. I have tried most of them. I am here to answer any questions you may have. But as long as you have a mower with a bag or a mower and a rake, this will set your garden straight with the least chances of making a mistake.

Good luck.

I just wanted to say that nasturtiums will take over, and may very well reseed. If you don't want nasturtiums there next year, you might want to try something else, such as Scott's suggestions.

Like you, I also spent a lot of time avoiding mulch because it was just so confusing for me. Like you, I wondered where and how to plant the seeds. I've had limited success plugging soil into the the mulch, but like Scott said, one usually pokes all the way down to the soil beneath your mulch.

What you can also do is put a layer of soil over the mulch to plant into (more like a lazagna garden), which is what I usually do since slugs here LOVE mulch.

One video that might really help you, if you haven't already seen it, is the Back to Eden video.



The author uses woodchips for mulch, but also mentions other organic matter can be used. He does a great job showing how to plant into mulch and it's benefits. As a word of "warning," the video definitely has a Christian bent, with references to scripture throughout. They mostly explain his motivation for gardening thusly, but, he does a fantastic job of showing how to grow with mulch, in a very permaculture manner.

don´t worry too much. just go for it.

i think, most important thing is to plant what you would like to eat as soon as possible. failures suck. they ll steal our motivation for gardening. so it s important that you grow stuff you like and get your successes. on that way you ll build soil (which you ve already done a good job at) and step by step kill the grass.

most plants will do ok with grass. some will need much more help (small herbs and salads etc).

for mulching you could also use tree branches with leaves or needles. the wood wont decompose in the first year, but you could collect the branches later. just use, what you have available.

EDIT:

nicole, thank you for the link, i bookmarked it and want to watch it later

jesse and kyle ... i d like to add some small thoughts. mulching has several functions. for your situation the most needed is to shade out, smother, suppress the grass growth. but it ll decompose, feed worms, bacteria, fungi etc. and create good soil over time. you can t have too much of good soil.

raspberries ... just plant them, like you normally would. they ll be higher than the grass, so no big problems.

sowing seeds on top of straw wont work. maybe some seeds would germinate, but very, very few. so either prepare SPOTS OF SOIL for them or grow starts inside and transplant. some plants would need help to win the race against the grass. just try and see what works. you might want to seed in rows (some people are against it, but it s good for NOW). then mulch left and right of the rows. you could use boards, carpets, fabric, cardboard or organic matter. just leave the row with seeds open. when the row is growing well, maybe you might take away the mulch/covering and sow/plant between the rows. radishes (small, red ones) come up quickly and have good leaves. when you sow them densely, they ll help. later in season buch beans would help. sow them densely and they ll shade out most other plants.

just fill in the empty spaces with what plants you d like and are fitting for that season. you could also seed flowers like calendula, they get bushy and have edible flowers.

a very cool thing would have been to get that grass (is it wheat?) to maturity last year, harvest it and make beer ... just for the fun of it. ... when life gives you a lemon, you make lemonade... when life gives you grains, what could you make out of it.

i d like to encourage you. step by step things will get better. i mean, each time you plant or harvest, you ll get rid of some grass also. it s just a bit more work now. this sucks for beginners, but you ll learn good and deep lessons. and you ll end up with very good soil there. so just keep going on. you can t do much wrong.

As much as everyone seems to like nasturtiums, I have to warn that not all plants do the same in all circumstances. I have yet to get more than a very sickly small nasturtium to grow here, but sweet potatoes made a fantastic weed suppressing ground cover last summer. That bed also had the best tilth of all of them after we pulled the sweet potatoes.

For a cheap and abundant mulch I get free ramial wood chips from local tree trimmers. If you're near a city or suburb you can ask if they're looking for a dump site. They get to avoid dump fees and you get free mulch. If you're a little bit further away, maybe they'd be willing to negotiate a small delivery fee. The catch is that they usually require you be willing to take a whole dump truck load at a time.

These suggestions are great! Thanks for all the help.

In Toby's book, he says that this "bombproof sheetmulch"—really a lasagna garden as Scott pointed out—takes about 6 months to turn into soil. We tried transplanting a few adult raspberry plants about 2-3 months after completing the project, but these died. Now that the garden is 3/4 year old, I wonder if that soil will be established enough to plant the raspberries into. Or should we add some soil pockets in around their roots?

It is a large garden. Mulching on top of it again would be a lot of work, but I see the solution to our seed problem in this. We'll talk about our resources and time for doing all or part of the garden this way. Otherwise, we can face it head-on with hand-weeding, out-competing it and so forth. Then crop again, or turn the straw over when it's young. Take it year by year, section by section of the garden. Do more every year.

I've also decided to get some plants started growing indoors, following the suggestions in this link:

http://www.gardenbetty.com/2011/03/the-no-brainer-guide-to-starting-seeds-indoors/

So we'll probably start nasturtiums, potatoes and cabbage indoors this years, 4-6 weeks before the last frost, then transplant the young plants in the newspaper cups. I don't mind having nasturtiums every year, unless they'll out-compete everything we'll try to grow in the future.

We have some strategies now! Thanks again everyone.

Jesse Fister wrote: Now that the garden is 3/4 year old, I wonder if that soil will be established enough to plant the raspberries into. Or should we add some soil pockets in around their roots?

When I plant raspberries into a bed like that I first pull away the mulch, then dig right through everything with a shovel making a hole about 1 foot diameter +/- and one spade deep. then I fill the hole with water and the cane and then a mixture of 50% well finished compost and 50% peat. Make sure it gets good contact with the roots. I inoculate the water with a blend of beneficial bacteria and mycorrhizal fungi MycoGrow and plant into that. Alternately you could use O-horizon soil/humus from a forest floor and no need to inoculate generally, if you have a fairly mature woods or forest nearby. Do not fertilise until the plant is well established. You can water with good compost tea though. Be sure to pull back the mulch after planting.

(To harvest O-horizon soil first rake away the leaves that are not decomposed. The partially decomposed leaves and soil directly under that is the O-Horizon. It should be loose enough to scoop up by hand. Then rake the leaves back over the area you uncovered so it can decompose replacing the O-Horizon and not harm the forest.)

Jesse Fister wrote:
It is a large garden. Mulching on top of it again would be a lot of work, but I see the solution to our seed problem in this. We'll talk about our resources and time for doing all or part of the garden this way. Otherwise, we can face it head-on with hand-weeding, out-competing it and so forth. Then crop again, or turn the straw over when it's young. Take it year by year, section by section of the garden. Do more every year.

I don't know if money is your limiting factor or if labor is your limiting factor, but you can buy a big round bale of hay and unroll it over that garden in 1/2 an hour or less. Same goes for the paper. Depending on the hay, it might be seedy like your straw was though. That's why before I suggested grass clippings, both free and weed free as long as you keep your grass mowed before it goes to seed. High nitrogen too. So you don't have the problem of nitrogen locking found with wood chips or straw.

(Nitrogen locking is when you use a high carbon material, Think of this as a carbohydrate. The nitrogen compounds think of like proteins. The biology decomposing the material needs both carbohydrates for energy and proteins for building their bodies. But a material low in nitrogen this means most the nitrogen is in the bodies of the microorganisms decomposing the material. Not much left for the plants until the organisms finish decomposing the material and die off, finally releasing the nitrogen to the plants. By then though it is usually too late, as the rapid growth phase for the plant is already passed.)

jesse ... no need to start potatoes indoors. find out, when people plant them in your region. there s a way to get potatoes to start "sprouting" indoors. i think, it s to put them on the windowsill (1 layer) to help them sprouting. no soil needed for that. plant them, when the sprouts are 1-2 inches long.

what s the area of your garden? i think, it s possible to get it running in less than 1 year. cause not all plants will start at the same time.

maybe a cover-crop/green-mulch would be good for the ares you do not plant at that time. has any body advice on that?

Have you thought about flame weeding the undesired new growth? That's fairly easy to target, not expensive, less tiring than a new layer of mulch, and less complicated than animals (though of course animals have positives). You could then hand weed any areas where you have your desired plants growing.

https://www.uvm.edu/vtvegandberry/factsheets/flameweeding.html

Yesterday I went out to check the soil for the season. We're still a ways from being ready to plant, except for a few varieties indoors. We are in zone 5b here, so last frost is anticipated to be between June1-June10.

It wasn't much at first glance. Straw seed and pigweed (we think) from last season had done their work.



Until I started to dig. Everything moved easily by hand. Every handful revealed several worms at work.




So the soil looked like it was good. It will continue to get better. But there was still this to deal with:


So we decided to pig nuke it! The neighbor owns pigs we're going to use. Building the second half of the fence only took an hour. We used the permaculture idea of gathering resources from right around us. "oh look! abandoned fence materials just over the fence. And chicken wire right there already. Ok, I guess we're building a fence to keep the pig in and the chickens out." So we did it!


We're ready for the pig, and this should prepare us in time for growing season!

We also got our heirloom seeds in this week. So exciting! I have them all sorted into groups by date of planting, whether indoors or outdoors. For the indoors seeds, I made a box full of of newspaper starter pots. We will begin planting some of these soon.

Nicole Alderman wrote:
One video that might really help you, if you haven't already seen it, is the Back to Eden video.

The author uses woodchips for mulch, but also mentions other organic matter can be used. He does a great job showing how to plant into mulch and it's benefits. As a word of "warning," the video definitely has a Christian bent, with references to scripture throughout. They mostly explain his motivation for gardening thusly, but, he does a fantastic job of showing how to grow with mulch, in a very permaculture manner.

Thanks for this link! The old farmer who runs the property got very excited about this and asked us to search out a source of wood chips. He wants to try two other large plots using this method for gardening. That's really exciting for me because it means more experimentation!

I tend to stalk tree trimmers. If they're close to you they can usually be persuaded to drop off a dump truck load of chips. Saves them drive time and dump fees.

The electric company hires regular tree trimming crews to clear the electrical lines. Possible they're doing this in your area.

Today we put the pigs in. It's kinda scary watching 'em till up all my delicate soil. Now we know why it's called 'pig nuking.' Hope this works!

video

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After several weeks, the pigs have done their due best - and succeeded! Next comes a top layer mulch!

Your gardening resume now has to be ameded to include:

1) "Persuaded several coworkers (the pigs) to weed and fertilize garden while I supervised, without asking for wages of any kind."
2) "Turned WEEDS INTO BACON!!!"

You'll soon lose that newbie status. Enjoy that new garden!

To make it easier to understand bombproof sheet mulching, I found a diagram online:

I found that it works great, but the amount of material it takes to cover an area of any size is truly tremendous.

Jesse Fister wrote:Alright.  Thank you for all these replies.  I am starting to formulate a strategy in my mind.  Let me rephrase:

Pig nuking is a last resort method that will work well.

Hand weeding should be easy in new soil.  We can plant Nasturtium to out-compete the grass over areas we can't manage this coming year.  Over the whole garden if necessary.

To plant, we should add some good soil in little pockets or rows, along with the seed, then mulch around it.  Big leafed vegetables like squash and potatoes will help us shade out the grasses coming in.  Start with potatoes first.  Smaller herbs and vegetables may be more difficult to deal with, may require more hand weeding, and a careful eye to see what's growing and what isn't.

We should add compost pockets at intervals into the garden to aid the worm community.

Questions:

What should I be adding as new mulch?  
Is new mulch even necessary with all the bio-mass we have in this garden?
Does it ever work to just drop a seed into what's already there, without adding new soil/mulch?
The neighbor has a big supply of mature raspberry plants.  How should we transplant them?

Thanks everyone!!!

Jesse and Kyle

I like the sheet mulching idea. I would have done it different. I would have covered it in the mulch, (2 inches deep of woodchips, 5 inches deep of straw, etc), even if it was a few inches only the fact that you put dirt on top of the sheet mulching gave way for small seeds to grow in. The main points of mulching in general is to warm your soil, maintain moisture and reduce the amount of weeds that can grow. Your weeds are rooted in the soil on top of the cardboard.
There’s an old book, the woman is passed away now, but her name is Ruth Stout, “The No Work Garden”. She suggested at least 10 inches of any kind of mulch would not give way for the upper levels for the seed to grow. That is the philosophy I’ve used in my garden. It has gone well for me. but the sheet mulching seems like a way that it would reduce the need for so many inches of mulch but I would not add soil. Adding rocks to weigh down... gravel or other mulch on top to keep it from blowing away would be my suggestion.
To sum up I would just add one more cardboard layer and one more layer of mulch. Make sure that when you go to plant that it’s been well watered in that area the cardboard will be easier to perforate