N-fix 7: Vetch

I was rather dissatisfied when finished with the Top ten ground covers for food forests series because I didn’t include an N-fix in the lineup of dynamic mulch. Vetch would be my first choice.

Crown vetch (Securigera/ Coronilla varia) is indeed the tyrannical ruler of the genus. It’s industrial grade ground cover, produces medium levels of nitrogen, stretches 3-4 feet tall, and eats as much as 60 ft of new territory in all directions via rhizome spread every year.

img_4764

I’ve only seen this number in reports. I’m guessing the ground where these measurements were taken was the most fertile sandy loam on the face of the planet, or someone dropped a bag of fertilizer. I’ve never seen it spread more than four feet a year -if it spreads at all. many readers have likely seen this plant along highways where governments have seeded it. Erosion is a thing of the past once this perennial is established, so they have encouraged its use.

Once established though, they can start new colonies via seed. As a result, many governments have removed it from their official list of recommended plants.

It’s a little late. I have some patches appearing by the road at the edge of my food forest, and one of my clients has several healthy patches around their property. I have in fact installed this plant in one client’s system, because it really is quite useful, and easily controlled, if you know its habits.

The one system where I installed this for instance was a very high production food forest with long rows of shrubs and fruit trees running along swales (not my designs. I was brought onto the scene in the later stages). The owner wanted a system that could be managed by laborers simply weed-whacking the place every month or two. With this mentality, the owner had started by laying black woven plastic mulch under the plantings -despite my disapproval. It didn’t take more than two moths before weeds found their way through. He was aghast when I showed him. Finally open to my suggestions for a dynamic mulch, crown vetch was the perfect candidate.

As a dynamic mulch, it can exclude grass. Sometimes, if the grass is well established, the two may persist together. If well established, it’s nigh inpossible for weeds to get a foothold in the crown vetch’s domain.

It grows well seeded among daylilies, and most any plant that grows more than three or four feet -a food forest cover.

The crown vetch in my food forest has to creep across the upper grain patch before it can invade any of my plantings. This is one of the most poor spots in the food forest even the crown vetch can’t stomach crossing. I simply tax it for its nitrogen rich growth about the time it comes into bloom. Because it can be pulled so easily, I simply yank up whole armfuls to feed other parts of the food forest. As you can imagine, the patch is expanding at a snail’s pace.

My clients have done the same, and find their patches stay put.

Hairy vetch (Vicia villosa) and wood vetch (Vicia sylvatica) are both annuals, but have scarcely less ability to spread. Hairy vetch is used commonly used as a ground cover in vegetable gardens to be tilled in as a green manure. It and wood vetch are also medium level n-fixers. I have seen vilossa reach about four feet tall as it meanders around, such as below with wine-raspberry. Reports say it can reach as much as eight feet. So long as it doesn’t bloom and seed, there isn’t a problem.

img_1147

I actually let the thing seed in my food forest because it grows right among weeds, grass, you name it -without complaint. I love it. When it blooms, I nab as many as I can for mulch, leaving the rest to seed. I really just wish I had more.

I came hit the jackpot the other day at my step-grandmother’s garden. She has the wood vetch, and a lot of it. I gathered a bunch of the pods as pictured below, which popped, flinging seeds every which way even as they sat in the bowl.

img_4745

I planted them in a problematic part of the food forest to see how well they might compete with the grass. Perhaps they’ll clear the place for me in a similar way sunchokes can. in the bed I found it growing so happily, it was hardly three feet tall. I’ll just yank them up or cut them down before they make any very much seed.

IMG_4764

Ground cover infographic

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.

Scaled 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.

Update: It’s launched! Mastering the Growing Edge is live if you want to check it out. 

 

Sunchokes

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.

35172408 - jerusalem artichoke flower in garden

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.

img_1881

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.

28174029 - topinambour  helianthus tuberosus  plants
Sunchoke sprouts
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.

43792512 - jerusalem artichoke plant
A young, thick patch of sunchokes.
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.

Photo credits (because I’ve accidentally killed so many of my sunchokes with this method): Top photo by elzeva, second down Gurcharan Singh, third down Harald Biebel, bottom Tawee Wongdee