Are Weeds Humanity’s Enemy?
—Michael Pollan, Second Nature: A Gardener’s Education
I. Weeds Born in Agriculture’s Shadow
From ancient times to the present, few farms have ever been free from the nuisance of weeds. Compared with other tasks in the production cycle — even pest and disease control — weeding remains the weak link in both mechanisation and the use of agrochemical products. Faced with this reality, when people try to view weeds positively, what they first think of tends to be limited to their value as food or medicine. Yet I believe that, for ecological agriculture, the greater significance of weeds lies in a shift of perspective: to borrow the anthropologist Lévi-Strauss’s phrase, weeds are not merely good to eat but also good to think with. In other words, weeds prompt us to ask: what should the relationship between humans and nature be?
The very existence of weeds already offers a tentative answer to that question. Just as rubbish is a resource put in the wrong place, weeds are plants whose virtues have yet to be discovered — and they were, fittingly, born in the shadow of agriculture. Among the thousands of wild species, those successfully domesticated and put to use became crops; those that were shunned yet competed with them were relegated to the category of weeds. The boundary between the two is drawn by human livelihood and cultural need. Few people realise that barnyard grass — long dismissed as a “noxious weed” in rice paddies, whose sustained selection pressure has caused it to disguise itself remarkably well as the rice plant, a case of Vavilovian mimicry — was once itself one of humanity’s staple foods.
Once we step back from an anthropocentric viewpoint, weeds lose the moral connotations of impurity or danger. Their appearance is simply a response to disturbed nature and disturbed soil — an expression of the principle that nothing can be built without something being first torn down. In the eyes of ecological agriculture, weeds can mend what is askew in the land and may therefore serve as an antidote to some of the long-standing ills of modern farming. For instance, weeds that thrive in areas of soil compaction tend to loosen the ground, while those that grow in loose soil excel at binding it. Where the earth lacks certain essential elements, weeds step in to concentrate them; heavy metal contamination in some soils, too, is absorbed and metabolised by weeds. Once the soil regains its balance, they bow out in silence; conversely, the moment people insist on weeding or disturbing the soil, they refuse to relent.
During a group learning session, one insight from our intern Liangzai struck me deeply: “Weeds are a mirror, revealing what lies in the heart.” In traditional agriculture, the contest between human and weed was never so bitter. Weeding was a routine chore, no different from sweeping; hand-weeding itself aided soil moisture conservation, and weeds served in all manner of ways — as famine food, medicine, firewood, fodder and even material for weaving. It was only after modern agricultural intensification threw the balance of soil, water and ecology into turmoil that weeds became a natural enemy human civilisation had to conquer. But for every foot the Way rises, the Devil rises ten. In conventional agriculture, chemical weeding — single-mindedly chasing efficiency while wholly ignoring the interplay between weeds and soil — has in fact forged “superweeds”: faced even with powerful herbicides such as glyphosate, weeds will, in the end, develop resistance through mutation or gene flow. Ecological agriculture’s “weed management”, by contrast, requires the farmer to walk fully into the ecology of diversity — not merely to tolerate or exploit weeds, but to foster life through ever-unfolding relationships in which cooperation and competition coexist.
II. How Ecological Agriculture Learned to “Dance with Weeds”
The first is to remove weeds that have already appeared, through physical means (hand-weeding, mechanical weeding, mulch film, etc.) or biological means (biopesticides). However, any single weeding method will, to some degree, impose evolutionary pressure on weeds, giving rise to homogenised weed communities.
The second is to use ecological principles to reduce the occurrence of weeds — for example, crop rotation, intercropping, stale seedbeds, drip irrigation, or even managing weeds with weeds. The essence of this category of technique lies in creating uncertainty of timing and diversity of conditions, making it difficult for weeds to settle into a predictable survival routine.
The third is to let weeds become a positive force in building the ecology of the farmland. When the ecological balance approaches completeness, crops grow more robust, and weeds cease to be a problem. This perhaps echoes an ancient maxim: “The highest physician heals the nation, the middle physician heals the person, the lowest physician heals the ailment.”
Yet the ideal of ecological restoration often has to yield to the hard pressure of farm revenue. Organic yields are often lower than conventional ones, and many ecological farms were established on “sick land” — plots contaminated or depleted by chemical agriculture — requiring more time for recovery. Some farms have chosen more immediately effective weeding methods, even at the cost of greater labour and resources. At Guiling Farm in Dali, Sister Yuhu believes that an ecological farm relying solely on such methods has not truly broken free from the logic of conventional agriculture; the innate potential for healing has not been trusted or activated.
If we focus only on yield, we miss the “inexhaustible treasure” of ecological agriculture: sustainability and resilience — which means crops are better able to withstand adverse natural conditions. At Guiling Farm in Dali, rose trees are planted at much wider intervals than on most farms, intercropped with other fruit trees, shrubs and the like, while weeds grow unimpeded. But do not underestimate these weeds: push aside the lush stems and vines, and there lies a carefully tended layer of humus threaded with mycelium, interspersed with fallen branches and leaves, nurturing the topsoil — a sensory rush of brown, soft, moist, fresh earth greets you.
Sister Yuhu recalled that during a prolonged drought in Dali, rose gardens elsewhere suffered devastating losses, while Guiling Farm’s plants weathered the crisis. What equally baffled other growers was that the pests rampant in their own fields were nearly invisible here. It was the biodiversity created by the weed community that completed the food chain, preventing any single pest from running unchecked.
Ecological agriculture brings another surprise to our lives: the flavour of food. For consumers who have tasted produce from ecological farms, little more needs to be said. But standing on healthy soil and tasting what it offers brings a more vivid and holistic nourishment. Sister Yuhu casually picked a few fruits from a plum tree for us. The sweet-tart juiciness made it hard to imagine the bitterness of this same tree when it first settled at the farm. The tree had originally been discarded by someone else and rescued by Yuhu; the fruit in its first two years was barely edible. She thought: wait another year, and if it is still this bitter, just dig it up. But the following year, perhaps through the “detoxification” of the farm’s soil and water, the taste had transformed dramatically. Patience in days past had forged the connection of today.
III. The Scope of “No Weeding”
The first step is to ease the drive toward intensification. If one does not chase the utmost in yield per unit and uniformity, a smattering of weeds does no great harm. Guiling Farm has three small plots planted with different rice varieties. When it comes to common weeds such as barnyard grass growing among them, Sister Yuhu simply says: don’t pull them. One might say she has accepted a measured amount of barnyard grass as a member of the farmland system — letting it grow as it pleases without affecting the rice harvest.
The second is to leave space elsewhere for the weeds. Ecological farms growing grain crops on a larger scale, such as Lüwo Farm in Xi’an and Yuefeng Island in Kunshan, will choose to fallow a field for a season, letting the land be “replenished” by weeds that help restore its vitality. For weeds and crops, for the land and for the people, this is a chance to breathe and to make peace: by the next season, the pressure from cropping sequences eases, and the need for fertilising and weeding diminishes. At Xiqing Farm in Beijing, the strawberry beds are kept weed-free, but around the perimeter they plant Brassicaceae and other insect-attracting crops, thereby letting the surrounding weeds fulfil their ecological pest-control function.
Beyond time and space, the boundary between weeds and crops can also be blurred through varietal diversity. Yuefeng Island carries the task of conserving heritage varieties. Among its collection of over a hundred rice varieties, roughly twenty are being propagated in rows for multiplication, while around forty are preserved in small one-metre-square plots. These conservation plots require extra reinforcement with bamboo stakes and string, and bird netting and shade netting are installed as needed. Here, the range of temperaments among the rice varieties opened my eyes: early-ripening and late-ripening, tall-stalked and short-stalked, paddy and upland — an inexhaustible variety. Some of the tall-stalked types are especially striking: their leaves bend over like untamed tresses, and their panicles fan out at will — in virtually any other paddy, they would be pulled up as “wild rice” or “weedy rice”.
IV. The Unknown Fate of “Invasive Alien Weeds”
Among the weeds I have encountered, the one I find hardest to see without prejudice is Canada goldenrod. Introduced to Shanghai and other places as an ornamental plant in 1935, it gradually spread into the wild through its extraordinary reproductive capacity and tolerance for poor soils. At Lexiangu Farm in Fengxian, Shanghai, some idle plots have, within just a few years, become the domain of this invasive alien plant. Dense thickets of over-head-height, woody-stemmed specimens grow with unchecked vigour, their allelopathy strangling every surrounding herbaceous plant in the cradle — veritable fascists of the plant kingdom. Each year, Teacher Yuan Qinghua leads a team to cut them down before they flower, but such measures can only temporarily contain their outbreaks.
For those few days, our main task was weeding. The mower could only handle low-growing grass; the broad swaths of Canada goldenrod had to be dealt with by hand, using sickles or chainsaws. Teacher Yuan patiently corrected my grip and technique, and as I grew more proficient, one swing of the blade sent a whole row toppling to the ground in an instant. A kind of martial fervour welled up within me, heedless of sweat-soaked backs and bone-deep exhaustion, driving me to trample over the fallen stalks and press deeper into the wild clearing. This was a more absolute enmity than in conventional agriculture: a practical production need had been sublimated into a moral imperative.
My feeling was not unique. In our exchanges, even those partners who wished to weed less or not at all could not entirely avoid a hostile response towards noxious weeds. Perhaps this rests on a principle: life guided by reciprocity and inclusion may coexist, but life driven by aggression and exclusion must be held in check. Eradicating noxious weeds, then, is a “necessary evil” in the improvement of agricultural ecology.
“Invasive alien weeds” are not simply a matter between people and nature; they also carry within them the imprint of human activity. First, from early colonial history to the human migration and expansion of power in the age of globalisation, certain species hitched a free ride. Second, the regions where invasive weeds are most severe tend to be the very lands most profoundly disturbed by large-scale land clearance, chemical agriculture, industry and urban construction; the weakening of native ecosystems objectively sweeps away the already limited competitors and natural predators for the interlopers.
Even understanding this logic, we can only accept the fact that Canada goldenrod has come to this land, and no one can predict its future. Perhaps native weeds might be used to compete with it; perhaps a new natural predator will emerge to keep it in check; perhaps people will discover a new use for it. But this takes time, and it inevitably means harm to local people and other species. The one certainty is that, on this land perpetually disturbed by human hands, it is unlikely to simply disappear.
Perhaps the three-leaf beggar’s-ticks, which arrived earlier, can offer us a little more confidence. From an ecological standpoint, it is hardly a well-behaved successional species, yet it objectively restores disturbed and polluted land, drawing itself into the fabric of daily life through its many uses. In Stone City, Lijiang, Yunnan, like its native relatives it has become embedded in local people’s body of knowledge through its wide range of applications (medicinal, fodder), and its Naxi name makes it hard to recall its invasive origins. At Sister Yanping’s Baicaoyuan, beggar’s-ticks have even become a wild green on the dinner table. So it turns out that traditional farming communities and ecological growers do not mechanically draw a line between native and alien species, nor do they elevate so-called “noxious weeds” to a matter of friend and foe. These weeds bring trouble, but there is room for transformation: at the very least, it is edible.
Having come full circle, “thinking” returns to “eating”. As the anthropologist Annemarie Mol has shown, eating and relationships of feeding shape the fundamental bonds between the lives of different species. Humans feed crops and weeds in opposite ways, and eat them in opposite ways too. After all, no finite life is self-sufficient — whether a weed or a person, one must ultimately learn to coexist with other life in the environment, giving and taking from one another. When the farm’s sheep eagerly accepted Canada goldenrod as a fine meal, my prejudice against this weed softened somewhat.
