Last time we blog-interacted I was talking up the pleasures of cardboard as a garden mulch. As of today it looks something like this:
Sentenced to rejoin the earth from whence they came in some part of a tree.
But cardboard is cumbersome to work with, despite its delights.
You also gotta have the cardboard by dint of keen foraging. Either that or you are buying too much packaged stuff...
So I got to thinking as I was rejigging my backyard into Winter mode.
Last Sunday the Misses and I visited a local nursery. We did not buy anything, as we aren't always impulsive. Lovely place. Plants were all of great quality and variety. A succession of outdoor rooms per microclimate put together.
What enthralled me was what we walked on as we browsed: the place was carpeted with weedmat. you know the black stuff that allows the water and air through but suppresses weeds.
I had worked a lot with weedmat because I put it under our stone paths ten years ago (something I now regret) and we had huge roles of the stuff to play with at the school garden I managed.
I later deployed it as a liner for my milk crates to create a milk crate herb garden. Wonderful drainage -- I've now got something like 25 milk crates in production. The crate acts as a frame for the weedmat.
So using it as a naked carpet covering was a surprise as it is usually used UNDER a layer of mulch. So I started to experiment with the weed mat I had -- and laid it down to carpet my dojo/gym area. An area where the grass will not grow.
Impressive. Nailed into place with tent pegs. Makes a good surface to bounce around on.
Why not use it in the vegey garden to protect newly planted seedlings.
Same principle as the cardboard. Just make a hole in the mat for the plant to grow through.
I 'could' have covered a large area with weedmat, but really there was no need.
I only wanted to protect new seedlings.
Talk about easy peasey. Much more workable than using cardboard or paper or even throwing down another layer of mulch to suppress weeds.
All good I thought. So I planted out a few different seedlings.
I'm thinking different sizes with different hole layouts so that each sheet is its own template.
Note that you need to cut a + shaped hole so that the plant stem has room to expand and you can get your fingers into the dirt to plant the seedling.
In a fit of research, I went back and read sections of the market gardeners bible, Jean-Martin Fourier's The Market Gardener.
Fourier loves weedmat and makes a celebratory case for its use as a quintessential organic gardening tool.
At his farm he lays out weedmat over every bed once harvest is completed and 2-3 weeks of that suppresses the weeds' enthusiasm to come back. He uses it to protect the soil in Winter (as mulches do) and points out that the mat, being black, is a wonderful way to trap heat in the soil.
You can see how I've applied the mat to my needs. I've re-used old off cuts and after laying out the holes and cutting them, simply held the mat in place with some old logs I have kept for unknown needs.
I'll still mulch with organic matter as that's how my garden came into being. Although I won't be laying mulch material over the mat. Since I've gone all green mulchy keeping the Scurvy Weed tamed takes more effort than my laziness prefers. Indeed, I can prepare sections of my beds by laying down the weedmat a week or so before I plant out my seedlings. Maybe it is best to mulch and manure the bed -- then cover the new layer of mulch with weedmat as a pre-planting protocol 2 weeks ahead of time.
Covering the whole bed -- something we did in the school garden for the vacation periods -- can be wasteful if you start fiddling with the texture and fibre of the mat by cutting holes into it. Similarly when you cover the whole bed you may get moisture run off and the soil will dry out underneath if the mat covers the bed in a broad convex shape. Too much heat can be trapped underneath. Similarly, I'm not keen to use weedmat to grow perennials as that precludes re-use.
I am reminded of Square Foot Gardening as a design system I could adapt using weedmat.
To make this approach work, I gotta give deference due to my stabbing stick. (Pictured at left). I loves my stick. I use it to piece the soil and by wiggling it about I can create a hole just right for a seedling without disrupting the local soil life.
Holes in weedmat or cardboard are too narrow to wield a trowel about in. And when you've finished, lean on the stick to stand up.
If you look at the price of weed mat -- around $23 for 25 metres it's not a bad deal for an easier garden life. Look after it of course. Set aside some things to weigh it down. And have a storage plan for your cut pieces. Hypothetically, you can manage your whole garden by consecutively laying down weed mat to suppress weed growth and reduce your mulching efforts and/or bills.
You gotta add the organic mulch material because that is what creates soil and feeds its life. It's all about break down. Weedmat shouldn't replace organic mulches.
3 WEEKS LATER:June 26th
Here's a gallery update on some of the plantings.
Click on images for enlarged view.
I think that in some cases it is clear that the seedlings planted through weedmat have done better than those in cardboard. I suspect that the heat retention from the blackness is a factor. I'm also lightly clearing the underlying mulch away when planting with weedmat whereas with the cardboard I planted over the organic mulch.
It wasn't as if I did some major clearing -- I just swept the mulch -- both dried and green/growing -- aside with my arm, and plonked the weedmat on the exposed space. Just like slash and burn agriculture within a forest/jungle. Note how undisturbed is the area around the weedmat boundary. This is patchwork gardening using dry and green mulches.
In a practical sense, I suspect the best size for using weedmat like this maybe an approximation of 60cm by 60cm with leeway allowed for weighted instruments like logs, branches, stones, tiles or whatever. Banana stems are great!
Note that I am planting densely...
You want mat cut to a size that can accommodate around 10 seedlings, I reckon. That way it is easy reach and there is less pull as you stab the holes. With a set number you know how many plants you can expect to harvest. And make sure your + cuts are potentially broad enough to accommodate the different stem sizes of a range of plants.
I think the preferred option is to lay down your mat, secure it temporarily -- with a weight, a tent peg or your foot -- and stab all of the holes through the + holes you cut previously. Then plant your seedlings one by one. Secure two sides so that the wind doesn't turn your mat into a magic carpet.
Don't throw mulch on top because you want to recover and recycle your plastic weedmat -- so you need to be able to find it to recover it.
The Milk Crate Herb Garden around the weedmat drill mat Portuguese Cabbage:(Couve tronchuda) Spring Onions: who hate weeds. Okinawan spinach growing feral in foreground.
Looking at other weedmat projects I note that all of them I've reviewed use the mat to cover extensive areas. I can't rule on commercial horticulturalists use of the material, but in the kitchen garden I'm advocating an eclectic usage of short pieces for small block plantings of seedlings. I'd use cardboard always, but while the cardboard is organic and will break down like other mulches, it doesn't sit as well on the soil and is cumbersome to plant annuals through.
Paper, on the other hand, is, in my experience, a Permaculture fantasy.
Other advocates also create big round holes in the mat, often by burning (!) after laying the mat down. Definitely use the + cut instead and stab your holes in situ. Seedlings are easily 'stuffed' into the holes you make.
Do not use plastic weedmat for planting perennials. Make sure you often rest the mat zones by re-mulching with organic mulches or allowing the spread of green mulch or ground covers back over the freshly harvested zone once the mat is removed.
At the moment I have approximately 20 or so mat pieces of different shapes and lengths I can use for planting out seedlings. I expect those mats will last me for years as the commercial product is remarkably durable with a very good ability to survive relentless sunshine radiation. Paired with using cardboard (for perennials, single plantings, ramblers, etc), I think I'm on a winner.
You'll note from the images that none of the mats are snug (except for the walk-on drill mat area) -- like they are applied in commercial use. You want your soil and its critter life to breathe. Indeed, that is one advantage with plastic -- as it doesn't collapse onto the soil unless weighted down by another covering of mulch or is constantly walked on.
Cardboard will lose its structural tension and adhere to the soil which may not be what you want during the life of an annual vegetable.
What you are applying with weedmat is targeted shade which is still porous to air and moisture. You are asking your plants to live in a leaky tent with their heads outside.
SAMPLING SOME MORE ACTIVITY: JULY 17TH