Considering the economic production of crops we currently consider weeds
“Growing like a weed.” It’s a complement given to children, investments or a small business. Not so much to an actual weed.
Still, it rings true. Weeds outperform crops. They’re quick. They seemingly appear from the ether: seeds dormant for decades or blowing in from afar. They reproduce at unfathomable scale, with masterful timing. They’re tenacious, they laugh at weather extremes that make crops wither, and they thrive in the very conditions we create.
But if the definition of a weed as “any plant growing where it is not wanted” is true, then getting rid of weeds is, in theory, as easy as changing our minds! I know — that’s the hardest thing of all. Luckily, it’s not quite spring yet, and we have some time to make like our ancestors and ponder the advantages of plants that do so well without us.
A Brief History of Weeds
Once upon a time, before they were crops, our modern foodstuffs were developed from free-living relatives. Diverse farming cultures the world over chose to invest in certain plants.
But which ones, and why? Some proto-crops made it on tastiness alone. Others were so clearly medicinal, or long-keeping, that they earned spots in the corner of the pantry. But in the staples department, where community-building calories come from, farmers have been universally smart enough to oblige themselves of plants that were already winning in the wild — those that were vigorous and productive and that fit the climate and the available tools of the era. By partnering with plants that succeed reliably — by changing our minds — we changed weeds into crops.
Then came breeding. Over eons of selecting for specific appreciated traits, there was a trade-off. Some of the vigor and reproductive success that made the original plant so appealing was lost. The resulting loss-of-function mutations can only survive so long as farmers contribute extra work and care, performing some pretty basic functions on the crop’s behalf. Humans are emotionally geared to caring for the weak — perhaps because our babies don’t come out running, like other species. The un-nurtured weeds, though, were — and still are — fit without assistance. They are ready to win — the ones to put money on in a fight. I think there are lessons here, and strengths to team with.
The world is amok with plants that have never been considered, or discovered, or found yet to be a good fit, or are escaped domesticates — or have otherwise evaded our interest. But we continue to see new domestication and cultivation events.
Cultivation is observation and tending; it comes before breeding. Care, harvest and processing techniques determine what can be farmed. Major genetic breakthroughs are rarely required. Wolves became dogs through repeated close contact, not by intensively breeding captive pups for generations till they were fit to pet. For better or worse, eel, shrimp, salmon and lobster are also farmed today, due entirely to technology and technique. Rhubarb, hailing from China, is quite young for a crop, at only 2,000 years of domestication. Pecan tree care is less than 400 years old. Sugar beets have only been a thing since the mid-1700s. We are a scant century into commercial blueberry culture, and the first intentional cranberry crossing was in 1929.
Kill, or Co-Harvest?
The point is that we are very much still in the golden age of discovery and agricultural experimentation. In a world of combines, refrigeration, precision-ag and deep science, it’s a remarkable time to rethink the weed-to-crop pathway. In every region, there are candidates that haven’t fit the tools at hand until now. Continued pressure on farmers to keep producing at the highest levels, while being part of climate solutions, means we can’t afford not to look at the strongest plants in our fields.
However well-intentioned agriculture is, it does its greatest environmental harm in the killing of weeds. The first plow and cultivators accomplished what herbicides and no-till drills do — what the flamer, zapper, laser, crimper and mower do, as with mulch and tarps, and even hydroponics — these tools are all in the primary business of keeping down weeds.
The problem is that we’ve worked backwards, forcing living systems to fit our harvest technology by removing all but the crop, rather than designing harvest technology to fit the reality of our fields, where multiple types of plants want to grow together. Thankfully, welcome changes are coming in this space. Intercropping and relay cropping are inspiring confidence, and growers are stepping up with experimental efforts. Better combines and pickers that tolerate more weed seed and debris are a big step forward. Advancements in seed-cleaning capabilities allow us to harvest more of the diversity from a field and sort it out later. What is lacking are true multi-crop harvest solutions.
This engineering project must simultaneously be demanded by enough growers for machinery producers to listen up, and it must be worked out by enterprising farm teams. The upside is that one could take a soybean crop AND a pigweed-seed crop together. Current intercropping research shows that one crop’s productivity decrease is more than offset by the boost of another revenue stream, and that total yields are higher than in monocropping. This is the thought pattern I find most promising for tenacious weeds. Rather than perennially devoting resources to cultivating, spraying or otherwise diminishing the diversity from our fields, let’s learn to co-harvest it and build markets.
A Weed Crop Starter List
Here, then, is a starter list of plants with strength to spare. I include cultivated crops with a propensity to spread themselves, outright invasives, and some common agricultural weeds.
To me, chief among currently cultivated — but under-appreciate — crops is okra. While, I do personally love it, I’m not just talking about the vegetable. I’ve been pondering this plant for years because its advantages are too numerous to ignore. Okra is globally adapted, drought- and wet-tolerant, wildly productive and largely free of pest and disease. Its sheer size and vigor make it competitive, and its expansive root network is a strong microbial partner and builds rich soil in place. It’s easily the most productive and care-free plant in many a garden. However, many people detest the idea of eating — much less committing to daily hand-harvesting — this slimy and scratchy veggie.
Luckily there are other uses. The leaves are a truly tasty cooking green. The daily flowers, open or not, are edible, gorgeous and superb for pollinators. Leaves and stalks make an abundant mass of high protein fodder for livestock, and no part of the plant is toxic to livestock, so it’s excellent in a summer pasture mix. The sturdy, fibrous stalk is on par with hemp in size and quality. And its extracted medicinal and cosmetic compounds are already a valuable market.
But all this is insignificant next to its greatest untapped value: its seed. Okra seed is a high-protein, high-oil and high-yield pseudo-grain. Planted in high populations, left to mature, and combine-harvested, okra culture resembles grain corn production. The cleaned seed can then be pressed into culinary oil, milled into nutty gluten-free flour, ground into protein powders, roasted and cracked into animal feeds, popped into snacks, or put to any of the other myriad industrial uses to which corn and soy are — fuel and bioplastics included. This is a 21st-century broad-acre superfood seed crop. Breeding, harvest and processing efforts are needed, to be sure, but the plant is there, eager to serve. See Chris Smith’s book “The Whole Okra” for a deep dive, and reach out to me if you are interested in growing grain okra. There is excitement and investment in this space.
Asparagus is certainly well-enough known, but it makes this list for its merry tenacity to escape the garden for an independent life on hillsides and field edges across the country. Anywhere kept relatively open and untilled is fair game. Its concentrated early-spring harvest window is a natural fit for market growers or supplementary income, and if it doesn’t sell, stop picking — it’ll be there next year. A unique advantage is that the fine fronds of asparagus, even at the height of summer, barely restrict light from penetrating below. This is annoying from a monocultural perspective, requiring lots of weeding or mulching. But consider how that might be a boon to a mixed crop. By the time spear picking is finished, it’s time to plant summer annuals. By the time those are harvested, it’s time for the asparagus stalks to be knocked down anyway. I see this as a potential fit for beans and peas, small grains, squashes and sweet corn.
Common fennel, Foeniculum vulgare, is a wonderful, weedy, medicinal that is used as a vegetable, garnish, spice and landscaping plant. It’s a vegetable in year one, with fronds and bulbs. Let it be biennial for flower and seed production. Due to self-seeding and splits off the root, escaped fennel can make hardy patches that last decades. “Wild” and domesticated fennel are the same, really, but the exceptionally hardy wild strains aren’t likely to make large bulbs. There has been a marked uptick in consumption of fennel in recent years, but still too few people have been introduced to it, leaving ample room for marketing outreach.
Daylily — the lovely, nostalgic, invasive ditch-lily (Hemerocallis fulva) — is naturalized across most of North America. All parts are edible at some point in the season and have been cultivated as food in their native Asia for thousands of years. Young shoots are decent. Flowers and unopened buds are delectable. But it is the tubers, or swollen roots, where this plant sends and stores its vivacious energy. They can be eaten raw or cooked, store well, and present real opportunity for scaled-up harvest.
Seek the “classic” plain orange or yellow daylily, not the countless hybridized landscaping varieties. Different colors mean different phytochemicals; differences in stature and growth represent changes to the plant’s energy attributes, and until proven (as with the naturalized, sterile, clumping types), do not assume suitability as food or crop.
The productive genetics are there — daylilies fend well enough for themselves with literally no care — but the culture of cropping them, while in all ways similar to potatoes, needs simple experimentation. Dig up and taste-test clumps in your area, find the best, plant them out, care for them a bit, identify methods that yield well, and experiment with efficient harvest/storage methods. As with garlic, the trick is in growing out your seed-supply to plant at scale. The goal would be to have an ultra-low-cost-of-production, reliable crop. Sales will come from industrial starch, thickeners, stabilizers and feed, if not as a vegetable for the general populace’s palate.
I will casually throw canna lily (Canna edulis) rhizomes in here for all the same reasons. Also known as Achira, this Andean staple has the largest starch grains of any vegetable and makes a superb flour for crackers and sponge cakes, etc. It is also used industrially and for subsistence growers as the starch source for Vietnamese glass noodles. Also, what a visual delight a field of canna and daylily would be!
Japanese knotweed, Fallopia japonica and variants, are indeed invasive, running rampant in wetland areas and streambanks, cracking concrete infrastructure, and generally winning. Its spread is primarily through hyperactively explorative rhizomes, which pop up at considerable distance from mother plants. Viable clones take off from any severed piece. Dense, shady patches emerge, thriving in self-made monoculture.
The rate of daily growth is flabbergasting, and they’re notoriously difficult to kill. Mowing stimulates it. Digging requires archaeologist levels of detailed excavation. Multi-year intensive herbicide apps are the “preferred” control technique. In 2020, USDA/APHIS approved a Japanese psyllid for biocontrol. We don’t have a great history with species introductions, but hopefully it’s a step forward. This is a legit land emergency.
The plant looks strikingly like buckwheat on steroids, and indeed — they’re both in the Polygonaceae family, along with sorrel and rhubarb. Growth rate is as impressive as buckwheat, just at grander scale. A 2013 study showed that knotweeds benefit more from native soil biota than native plant species do — i.e., in my interpretation, knotweed gives more energy and value to microbes than other natives. Unfertilized plants grow only to the extent that they are microbially partnered. There may thus be a case to be made that Japanese knotweed, like buckwheat, is good for certain aspects of soil health, or perhaps carbon sequestration. It’s still unequivocally bad for wild-life diversity.
Much is made of knotweed’s medicinal resveratrol and emodin content, which can be extracted. The main culinary use is the young shoots, harvested in the style of asparagus — cutting twelve-inch shoots to ground level, several times weekly, in spring. These have a lovely spicy/tart crunch quite akin to rhubarb and can be used in all the same ways — thus the most immediate ingredient market is for jams, baked goods, etc. Grazing with cows, sheep, goats and horses has been common practice in Asia — in fact, knotweed was introduced to Europe as animal fodder. A series of livestock feeding studies recently conducted in the Czech Republic showed several health benefits and no concerns, as part of a balanced forage. More study is needed, but habituating animals to knotweed grazing is a ready approach to keeping the stuff at bay, while getting free feed.
As with other invasives, either we create a value for it — i.e., we learn to harvest and eat it — or we watch it destroy what we know and love. I am not advocating the planting of Japanese knotweed! Rather, identify it in your landscape and weaken it through repetitive, diligent harvest by humans or animals. Limit the spread through use.
Lambsquarter (Chenopodium album) and pigweed (Amaranthus retroflexus) are globally dispersed weeds so long established in North America that they need no introduction and can no longer be considered “spreading.” They done spread.
I’m grouping them because of their many similarities. Both are members of the family Amaranthaceae, with similar habits and strategies. Both are notorious ag weeds, with numerous, sometimes overlapping, common names. And both have long histories as food.
Lambsquarter and pigweed are thought of as garden crops almost everywhere but the U.S. —usually for greens; and the name “wild spinach” is about right. Most plant-centric people have at least heard that the leaves and seeds are edible, whether or not we’ve tried it ourselves. I can attest that they are no harder to harvest than any leafy greens crop, and a good bit more productive and nutritious.
But harvest all the greens you want — they’re weeds because of their unbelievably productive seed set. That seed has been used, seemingly sparingly, by indigenous peoples across North America. But South and Central American species are straight-up staples. Quinoa is to lambsquarter as amaranth is to pigweed, just lacking a few centuries of selection for yield and culinary qualities. However, we now have combines and industrial processing and can harvest the heck out of this stuff!
These plants have already proven themselves “most likely to succeed” on millions of acres of farmland. We know how to get a strong stand established … just till in spring and walk away. If you have an area with known high pressure — or if after initial field prep it becomes obvious that you do — take a minute and ask yourself: “Is this stand thick and uniform enough to make an unintended but viable crop? Is it possible to take this to maturity? Can I tweak the combine and harvest the seed? Can I cut these as summer greens, replacing other more finicky crops? Am I enough of a marketer enough to sell it? Would it make more money, or cost less, than growing my other crop?”
No, I don’t actually expect anyone to grow fields of pigweed amaranth this year. But I do hope/ expect every afflicted grower to grab some handfuls of seed, bake some muffins, and at least talk to a local chef and bakery about future sales potential.
Violets, for a month or so in spring, may be the most profitable crop a small farm crew can pick. Precisely because so few people dedicate the time, they are a delicacy.
With some advance communication, one can corner a market among chefs, bakers and high-end bars, who use them for edible garnish, salad toppings, crystalized cake decor and cocktail flair. A couple ounces of violets won’t solve world hunger, but they can provide $25 an hour income to specialty growers. Violets are an easy-to-find, hardy, native perennial common across all manner of landscapes in east and central North America — from woodlot to weedy lawn to worked field edges. Of course, only pick from clean areas. Short-shorn turf is ideal.
If you found relevant value to any of these ideas, provide feedback and I can write more on the topic in future. Things that didn’t make the cut this time include chickweed, Jerusalem artichoke, dandelion, tomatillo, sorrel, castor bean, sunflower and velvet leaf. What weeds and lesser-used plants have you turned into a crop?
I don’t pretend that any — and certainly not all — of these crops are suitable to every farm. If one or two fits your context, then they are worth exploring. Everything has a cost. Reading this article has cost you time you could have been doing something else. Experimentation has a cost. So does stagnancy. It’s between you and your network to determine whether any of these ideas are worth pursuing, and at what scale.
I simply hope you come away with open eyes, looking out for the competitive advantages that certain plants hold and how to partner with them in new ways.
Nathan Harman is a farmer, a father, and a consultant. He is the agronomy leader for a team of growers, millers, processors, and distributors seeking to build a bioregional food system in the South that will pay premiums to growers based on the real, measured nutrient-density of grains and produce — including alternative crops such as those mentioned here.
