The mulch-generating polyculture for Mortal Tree’s PASSIVE garden system is going well. It’s the bed in Foundation for a future I am establishing with bricks.*
The intent for this bed, per A bit blunt method, was to shift the rocks every couple of months to kill off the grass underneath. This worked pretty well for most of the bed. I shifted the bricks in July and made a final small shift about a week ago. Above is the freshly shifted “mulch” around an amorpha.
I also tried covering a small part with grass mulch in May last year, and this took care of any weeds growing through the cracks. Below is the planting now. Like most fun times, there is a mess to clean up afterwards. This bed had a lot of fun last year. What you see is actually mulch I applied, the healthy comfrey, and some amorpha interplanted. I plucked out the little bits of green quackgrass, and look forward to some very lush, beautiful growth here come summer.
I plucked out the quackgrass when I shifted the rocks. Because they block sun and moisture loss, the rocks encourage the quackgrass to grow shallow, allowing me to just pick them up rather than pulling them. What roots did grow deeply are easily pulled because the soil is so soft under the bricks.
This soil conditioning is one if the main perks of using rocks. The soil life is everywhere, with centipedes, worms, spiders -even at this cold season. Soil between the bricks which heaved from the freezing over winter is unbelievably friable. It looks like it has been tilled.
Considering how low this soil is in organic matter, with a clay-coal base, with no amendments like sand or ever even being tilled before, I am very excited to already have such results. The moisture and soil life have brought it so far because I have created the right habitat, covering the soil. The organic matter is starting to accumulate.
Above are some amorpha leaves dropped last fall, which likely have brought in nitrogen the system formerly did not have. The plants were already beginning to nodulate in their pots when I planted them last year. If you would like to learn more about how I ensure they make nitrogen and get off to a good start, I have some notes here on Growing amorpha.
I also harvested some of the comfrey leaves last year, which I left around the plants I harvested from. This is breaking down into gorgeous soil, bringing in carbon the system did not formerly have.
Pictured is some broken down comfrey from a larger patch in the food forest. This new patch should be producing similar soil in the near future. It’s already well on its way.
*This could have been done with some large piece of canvas or the like, or a large piece of plywood. One of my clients decided to try clear plastic just to block water, which was still effective at removing the plants underneath.
Deep purple petal over bright orange stamens of Amorpha fruticosa melt into green, spotted little crescents of seed. These ripen in the sun to a dark brown, then white-gray and hold. I kept thinking these seeds would fall off, but even in January when I lately picked some, they were tightly attached.
They have a peculiar ability to sprout without cold -unlike most woody perennials that need months of subfreezing temps. They just need heat above 70 degrees F, and up pop little green leaves. Usually I soak the seed for a couple hours before sowing into flats. I start them in February in some years, March in others, but for my climate these both mean heat has to be provided.
I have to be careful with the dry air of indoor heating to keep the seeds wet, so usually cover with some plastic, and water often. We begin heating a small portion of our greenhouse about that time for garden vegetables, so these seedlings can soak up real sunlight from day one.
They are wise little seeds, and spacing their sprouting time -which outdoors would be a fail-safe against late frost and other catastrophes. For me, it’s a great convenience. Out of one ‘source flat’ as I call it, sprouts pop within three days after planting, but keep popping up for several weeks.
Usually I wait until the first true leaves show before I begin transplanting, then clear the flat of any sprouts with true leaves once a week.
Out of the hundreds I have grown, I find it’s best to start the seeds with potting soil, or compost with good levels of nitrogen. From here I separate into small pots or cell flats no larger than 2 inches across, filled with the same kind of nitrogen rich potting soil they sprouted in.
The heat and rate of drying in smaller pots, where the roots can quickly reach the bottom and be air pruned, has given superior results for me. They still develop very deep taproots once in the ground, but this root pruning while in the pot is helpful -in part because it stimulates more branching of the root system. Planting in extra large pots with nitrogen rich soil, many seedlings rot, and must be replaced two or three times over before each pot successfully grows a plant. On the other hand I have tried planting them this early in nitrogen poor soil, and they make little headway.
I think this best mimics the situation they would find in nature. Forests and grasslands have a thin layer of nutrient rich, fluffy soil on the surface usually, which quickly becomes clay or whatever the base soil of the area. I want to get the seedlings into nitrogen poor soil to induce nodulation (aka hosting nitrogen fixing bacteria as evidenced by the formation of little nodules). This is spurred on by a lack of nitrogen in the soil. The catch is it takes time for the young plants to find the bacteria and get the symbiosis set up.
Nature’s way seems to be nutrient rich soil at first, then less rich soil as the plant gets bigger, the roots deeper. My contrived biomimicry that gives best results is moving the seedlings once they have filled their small pots and gotten a bit root pruned (not pot bound, as in roots turning back on themselves) into larger pots of whatever size you choose, filled with nitrogen poor soil about 1/3 rd coarse sand. I usually mix nutrient-rich rock powders, such as carbonitite or granite, into this before filling the pots.
Usually I transplant into 4inch pots at this point so they are filled with their roots in a couple of weeks -about the time nodules start to form. Usually this is early June -plenty of time for establishment before fall. Those I don’t get in the ground the first year go into gallon pots by August, which they usually have amply filled by next spring.
I try to avoid keeping Amorpha in pots more than a year. They grow best put in the ground as soon as possible after they have acclimated to the nitrogen poor soil. After years of refining this method, I’ve had transplants pushing 5ft by the end of year one -well on their way to exploding every spring with growth, providing some of the best organic matter for fueling your plant projects.
Where to get the seeds? You might have a plant nearby, which I recommend you snatch some seeds from. Otherwise they’re very affordable, and widely available from Sheffield seeds (my first choice), Oikos Tree Crops (They advertise A. californica, but I’ve gotten their seed -and plants, and compared it against pictures and attributes on the USDA plant database, and they have the name wrong. It’s species fruticosa), or even Amazon if you shop there.
Sunchokes is number ten in the Top 10 ground covers for food forests series I started a while ago. To help put everything into perspective, I made an infographic.
The ground cover branch on the visual archive has links to all the original posts if you would like to find out more.
In general, the layout from right to left are ground covers that do well in established beds, to plants that simply wipe out other plants, and are excellent for bed building.
If you’re wondering how to share this on your own social media pages, try the share buttons below the post. I have most social platforms available for sharing.
I’m using the the term “dynamic mulch” to describe the ground covers, because ground cover has a rather flat connotation. Most gardeners think of them as useless plants that do nothing better than excessively clog the soil surface. They have much more potential.
I’m suggesting these plants as tools, not just for blocking weeds, but actively removing weeds, making use of otherwise useless plants through careful combinations, getting food from ground cover, improving the quality of the soil, and feeding other plants through their well calculated use. With the correct use, resulting from a more dynamic comprehension of plants, we are suddenly on the brink of an entirely new level of sustainable, productive, passive agriculture and gardening.
The infographic, and the Top 10 series are part of a bigger surprise to which some of you closely following me have probably caught on. It should be ready before the end of the month. My apologies for making you wait, but I assure you, it will be worth it.
Sunchokes, or Jerusalem artichokes (Helianthus tuberosus) are not so much a stable ground cover as masterful bed builders. They don’t just block, but obliterate grass lawn, taking the place of bed building mulch if handled correctly.
Its home is the American prairie biomes, where it stretches for sun among massive grasses and other very competitive plants. Placing it in the standard lawn, full of short European grass species, or even an overgrown field is like releasing a saber tooth tiger into a playpen with modern house cats. It’s a brute.
It begins by pumping nutrients from deep in the soil to power billowing clouds of leaves rambling up sometimes 15ft tall stems. At the end of the season, less fortunate species smothered below, it sucks all the nutrients gathered in its stems safely into the underground for storage in its edible tubers. Every year it sends out runners, some species more aggressive than others. One variety, “Supercluster,” Oikos Tree Crops sells is supposed to be well behaved, but most are decidedly imperialist, surging several feet out in all directions every year as resources allow. As long as it fills its nutrient reserves every year, the size of the open field it inhabits is its only limit.
To unleash the beast, get a bucket of the tubers in fall, and with a shovel, make little slits in the ground about one foot apart, inserting the tubers deep enough they aren’t exposed, and walk away. The days of the nearby plant residents are now numbered.
Don’t worry next spring when the tubers don’t sprout early. Sunchokes don’t like frost, and wait until late in the spring to pop up their furry little heads. I have planted these into completely unamended yards where lawn grass wasn’t even happy, but the ‘chokes still grew well. Results of removing grass and patch expansion are best if the patch is left a year or two before harnessing it for actual bed building.
It is very difficult to put strong beasts like sunchoke to use with brute force. You have to outsmart them. This you do by pinpointing their one weakness, and suddenly you have them in the palm of your hand. Because exploiting this weakness is so effective, I must go begging to my friends for new tubers in fall because I have accidentally wiped out my propagation patches.
I have quite a hard time removing their disbelief. Sunchokes are otherwise known in the gardening world as hard-to-chokes, which is why I don’t recommend digging up your newly cleared bed to remove the plants. I have never seen this work. Though you could swear all the tubers are removed, the plants always return. Some varieties were selected from patches sprayed with roundup -and lived.
Biologically, sunchokes are impenetrable tanks of ecosystem war, and have the potential to become the worst weeds for your new planting. I would not in any way suggest their use anywhere near your garden if it wasn’t for the one gap in their armor.
You see, ‘chokes go all out to ensure they get as tall and bushy as they can. Having invested every last bit of stored food from their tubers into the above ground stems, it’s as though the plant stood on top of the ground and could just be gathered up as a pile of stems to be placed somewhere else.
I discovered this one year when a particularly healthy, bushy specimen blew over in a windstorm, partially uprooting it. I broke the plant off, cracking up the lush growth to mulch the bed, expecting to see the plant return next spring. I was surprised when next year there was nothing.
Later, in a very dry year, sunchokes were the most lush thing in my food forest to feed my rabbit. She liked them, so I would snap off the growing tips, let the plants branch off to the side, and snap of the side branches to make rabbit happy. I started this when the plants were about 5ft tall, leaving about 4ft stems that in turn could return their nutrients to the tubers. Nevertheless the plants that normally topped ten foot came up the next year anemic, and dwarfed, barely reaching three feet.
The exact point in time when they seem most vulnerable is just before bloom at a certain time when the growth of leaves changes from being as tightly stacked and lush as possible, to becoming a bit more sparse, the stem getting harder, and the flower buds showing up quickly afterward.
Flowering, and in fact most dieback processes of plants, are accompanied by the production of ethylene gas, which in the ‘chokes I would guess also begin the back flow of sugars in the leaves to the more complex carbohydrates in the tubers, and oxidation of the stem fibers, making them woody and brittle. Cutting ‘choke down just before signs of this hormone’s activity seems to be their secret weakness.
In my climate, this means cutting the plants off about a foot tall in July. It is helpful to leave some stem to make lots of side shoots. A second cutting, about a month later, to remove the side shoots and what’s left of the stem, perhaps even some roots, in my experience, weakens the plant beyond recovery.
Some gardeners I have explained this method to ardently insist I’m wrong. They cite their own experience of mowing sunchoke patches for two years and the ‘chokes just growing up over and over again.
I have gotten excellent results with the method in my experience. That they were only a few years old unlike the decades old patches in these other reports may play a role. I doubt it though. On the one plant that blew over I saw a very large clump of tubers which I left in the ground.
Perhaps it is more a question of the plants adapting to growing less each time they are cut back, developing a sort of stunted homeostasis. They may have grown more miserly with their output of stored sugars. I think it is imperative that you allow the roots to put maximum growth above ground, then sap the last little bits of strength out of them with subsequent cutting.
Be cautious of course in planting the sun chokes and letting them run wild. If you closely follow the details I have given, I am confident you can get very similar results. Feel free to let me know how it goes.
Hacking off all this biomass leaves a lovely, thick mulch for planting into next spring. Grass is usually gone by this time. Adding some grass mulch early next spring ensures establishment is smooth the next year, but very little is necessary compared to normal bed building. If used well -in conjunction with the other ground covers, sunchokes are a real workhorse, with the potential to carry your efforts to the blissful state of an established, productive, ground thickly covered food forest.
The model in my mind of an edible dahlia seeds itself abundantly, and grows tenaciously; tubers just spontaneously generate over summer for fall harvest; the tubers you don’t care to dig freeze, so never become a perennial problem. I really do think this is a realistic vision, but it might take a little species trials to find the right one.
Cultivariable has done some excellent work gathering a collection of dahlias they consider edible, and are harvesting the seed for further selection. I read through an excerpt of his very informative book on his website which I subsequently grabbed a copy of (link below if you’d like to to check it out. It covers far more than dahlias) but saw no mention of self seeding.
He is already sold out of this year’s available tuber and seed stock anyway, so I looked deeper.
The species he raises are Dahlia pinnata and coccinea. Pinnata is the species most often cited as edible, and actually grows wild in the lower southeast US according to the USDA Plant Database -Mississippi and North Carolina in particular.
This was helpful when looking at my next best option -“Bishop’s Children” mix. I’d seen it many times in seed catalogs because it’s commonly grown as an annual from seed. It’s the progeny of “Bishop of Llandaff” -hence the name, and is believed to be cross between pinnata and coccinea.
This background information seems to originate from a single article profusely circulated and cited in Wikipedia articles. But the characteristics I see in pictures agree with the story. I think it’s worth believing. The seed is widely available so why not try them anyway?
The plan is to get the seed and sow some for carefully potting up and transplanting, the rest just spread around in opportune patches in the food forest to see how easily they take. Assuming they form plenty of tubers (most dahlias are daylength sensitive, some forming only small, and very few, tubers before frost) and assuming they taste good, they may become a prominent citizen of Mortal Tree, and perhaps find their way into my client’s gardens as delicious, productive little gem mines.
Above: The same heirloom dahlia in the opening photo, now harvested, with tuber harvest laid on the aerial parts which are now mulch.
Strawberries cover a couple of species, the ones usually cultivated in the garden being a complicated hybrid between the Virginia strawberry (Fragaria virginiana) and the non-hardy Chilean strawberry (Fragaria chiloensis) to give the large berries of Fragaria ananassa we’re used to.
I have the wild Virginia strawberry selection “Intensity” from Oikos which is very tasty, although about dime sized and only fruiting about two weeks in June. It’s the one I planted in the bed featured in the group and conquer update.
As a groundcover I’ve been less than impressed. It filled in, but seems to have an affinity for grass really. In the beds it seems to step aside, welcoming the grass in, and run out of the bed to frolic among the grass where it produces even less fruit.
Much better for groundcover is the musk strawberry. It has bigger leaves more like our modern type, and makes a thicker patch.
This fruits even less than the ‘Intensity,’ and you need male and female plants to get that small amount of fruit. I have eaten only about five between my and my neighbor’s patches, but there is no comparison to its flavor. Complete euphoria. A buggled up mis-shapen little thing, half green the other half a dark, blood red, but amazing flavor right down to its little core.
Best overall strawberry, with a happy medium of groundcover and fruit, is the Alpine strawberry (Fragaria vesca).
Alpine strawberry doesn’t run, it clumps. This helps in planning because you know where they will make the cover, unlike the running kind that shoot of in any direction and leave the original spot empty.
It may sound counter intuitive, but when planting for groundcover, don’t go with the four to six inch spacing recommendations most nurseries give. According to Michael Wellick of The Strawberry Store they produce best at one foot spacing. I find they fill this space to exclusion of weeds very well and make loads of berries. I pick about every other day, from June to September, and often get a descent handful of fruit off five established plants if I don’t eat them as I pick.
‘White Soul’ is my most successful variety. It’s very healthy and makes lots of fruit. ‘Alexandria’ has a very rich flavor in comparison, but I get less fruits, usually smaller. There’s a golden leaved cultivar of this that is very pretty.There are a ton of varieties though. Alan over at Of Plums and Pignuts has a nice review of them.
Main drawback here is they don’t make new plants. In theory, they could seed around; but I have yet, after several years of growing them, to find a volunteer seedling.
If you buy seed, they need some stratification, and often must be covered to slightly block light (an exact science, I know). I have had success covering with a clouded piece of greenhouse plastic to block light, stratifying in potting soil in my unheated greenhouse beginning in February.
My prefered method of getting plants has been to just buy them, as they sell for a buck or two a piece at a greenhouse I often visit. This was a more worthwhile endeavor a few years back because the greenhouse started these in cell flats with multiple seeds per cell and potted them up without separating. I could get three to five plants from one pot.
I went there last year expecting to get several, but on inspection for the fullest pots, found none of them were multiseeded. They were all single. Cheapskates.
I have since cut back on covering the food forest with alpines and began leveraging other groundcovers, such as mache. What is covered with alpine strawberries is well kept though. I really recommend you try them.