Tough Celery: Must Climate Change Carry the Can for This, Too?

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Foodthink Says

How exactly does climate change affect agriculture? Foodthink has published several articles on this subject already. Today we share the insights of a hands-on grower. Zhao Fei graduated from the College of Agriculture at China Agricultural University. After graduating, he joined Pingren Farm, which practises organic farming, and is responsible for vegetable production at two sites: Changping in Beijing and Lingqiu in Shanxi. On 8 January, he and two other fellow ecological farmers took part in a climate change talk at Beijing’s Harvest Festival. Zhao Fei used common vegetables as his examples to explain how extreme weather affects farming and the distinctive strategies the farm has adopted.

This article has been edited from his talk. We hope that through these vivid examples, you will come to understand more deeply the complex interplay between farmers, crops and the weather.

Please click the link below to watch the full replay of the Harvest Festival talk.

At the farm, we are always asked by consumers: why does the vegetable look like that? Why is this one so tough? Why is it so sweet? Why are there insect holes?

More often than not, the answer has to do with the weather. With climate change intensifying as never before, even ordinary consumers can now sense its effects directly through their food.

● Autumn 2022: a strawberry patch thriving with vigorous growth. Xingshou Town in Changping, where Pingren Farm is located, is the main strawberry-growing area in Beijing.

Let’s start with the strawberries currently in season. Temperatures in October 2022 ran high, and the strawberries grew vigorously. But this was not a good thing, because the plants put all their energy into leafy growth and refused to flower. As a result, the strawberry season was pushed back overall — from December last year to January this year.

In spring 2022, the broccoli we grew in Changping aged and yellowed in the heat. Neighbouring farmers reported similar problems compared with previous years. In the past, we always worried about temperatures being too low, but last year it was the other way around — temperatures ran high. A few unusual spells of brief, intense heat were enough to discolour the broccoli heads.

If consumers bring such broccoli home, they will notice that the layer of “epicuticular wax” on the leaves is thicker than usual. This is the plant’s way of protecting itself from intense solar radiation and preventing moisture loss in high heat.

● Lingqiu, Shanxi: open-field celery afflicted with leaf spot disease.
Customers who bought our celery last year experienced this even more directly. This variety of celery is called “French Queen” — normally very tender and crisp, but last year the high temperatures and humidity caused it to develop a great deal of fibre, making it tough and stringy to eat. The same conditions also made this cool-weather crop prone to disease: an outbreak of leaf spot disease wiped out several harvests. Even when some crops could be salvaged, the leaves had been so damaged by disease that they were picked off before sale, leaving customers with little more than bare celery stalks.

I. “The Way of Heaven Is Changeable”: Farming No Longer Relies on Predictable Seasons

We often hear the saying, “Agriculture lives by heaven’s will.” Many people take it to mean that natural disasters are common and harvests are always uncertain. But “living by heaven’s will” first of all means that farming depends on “the Way of Heaven being constant” — what the old saying calls “Heaven and earth keep their rhythm; the four seasons never go astray.” Farmers must first recognise the stable weather patterns of their region before they can plan their work. When I first arrived at the farm in Lingqiu, Shanxi, the very first thing I did was visit the local agricultural supply shops. By chatting with shopkeepers, I learned about local weather patterns. Combined with records of average temperatures, extreme temperatures and rainfall in recent years, I could then draft a rough production plan — knowing which crop to sow at which time, what disasters might strike, and what precautions to take. Spending time with the older local farmers also taught me their planting habits. Much of that experience has already been distilled into local agricultural proverbs. Our farm in Xingshou, Changping, for instance, traditionally sows peas around the Awakening of Insects (Jingzhe). In old Beijing speech, that is captured in the saying, “No pea goes past the Nines” — meaning peas must be sown before the Nine Nines period is over. This is the temperature window and season that generations of farmers have identified as ideal for peas: if temperatures are too high or too low, pea growth suffers.

● Local farmers usually sow Chinese cabbage around the Autumnal Equinox and start onion seedlings around the End of Heat (Chushu). The planting dates for these vegetables are fairly fixed.

As a child, my grandfather often told me, “If it rains on the twenty-fifth, no dry earth next month.” This is an agricultural proverb that has been passed down in my home region of Anhui, meaning that if it rains on the twenty-fifth of last month by the lunar calendar, the following month will also see prolonged rainfall. Another says, “Grey skies at Grain Rain, drenching rain by Start of Summer” — cloudy weather at the Grain Rain (Guyu) solar term signals that the next forty-five days will be rain-soaked. These are hard-won insights people have drawn from observing the turn of the seasons year after year.

Many people today debate whether climate change is a help or a hindrance to agriculture in any given region. But regardless of which side of that argument one takes, the moment the climate becomes erratic and unpredictable, everything a farmer once knew is put to the test. All we can do is feel our way towards new patterns through practice.

● This carrot looks rather unimpressive, because local temperatures ran high: the foliage above ground suffers premature decline, while the root below ground fails to shape up properly.
● Open-field baby bok choy in early spring, chewed through with holes by striped flea beetles. The whole point of sowing early was to harvest before the insects became active, but last winter’s warm spell brought them out too soon.
● Climate change can also bring pleasant surprises. This year, warmer-than-usual temperatures in Lingqiu, Shanxi meant far less late blight on the tomatoes, and local farmers enjoyed a bumper harvest! But according to reports, a nationwide tomato glut drove farm-gate prices so low — in some places down to just three jiao per jin — that the old problem of “cheap grain harms the farmer” reared its head once again.

II. Extreme Weather Disasters

Climate change has also brought even worse weather disasters. The old agricultural list of hazards — “wind, frost, snow, rain, hail, drought, flooding, and pests and diseases” — has become harder to predict and more frequent all around. On 4 May 2021, Changping in Beijing was hit by an exceptionally rare frost. At the same time, Lingqiu in Shanxi saw a heavy snowfall in May. At the farm we have Uncle Song, a local man in his sixties. He said, “Goodness, snow this heavy in May is truly uncommon.” That spring the soil temperature ran low, and every planting date had to be pushed back. It makes you wonder — is the climate warming or cooling? The truth is simply that the climate has become unstable, and extreme weather events are far more common than before.

● The farm’s polytunnels submerged in 2018.

Before I joined Pingren Farm, the site had not been flooded by rain in seven years. But since I arrived, the farm has been inundated three or four times, and at the worst of it almost the entire farm was underwater.

● Winter 2021: a single night of heavy snow crushed several polytunnels. The women workers at the farm remarked that they had not seen snow this heavy in a long time.
● In 2021 we were also hit by storm damage — the wind was stronger and blew for longer than in any previous year. The polytunnel coverings on the farm were torn off one after another by the gales.

For smaller disasters, such as frost, we can get by with protective structures or simple measures like lighting heating blocks. But if a major disaster strikes, it means a whole year — or even several years’ — worth of work goes to waste.

We have also considered buying crop insurance, but it really only covers a portion of disaster scenarios. For instance, the insurer’s definition of “flood damage” refers only to sudden torrential downpours. The prolonged rainfall of 2021 left the soil fully saturated; because our land sits low, salt-laden groundwater rose to the surface, salinising the topsoil. Sustained rain also caused the polytunnels to flood — the waterlogged soil made sowing vegetables impossible. Yet none of these situations falls within the insurance cover.

With rainfall now running high, the farm digs drainage channels every year, and they have been getting deeper each year. But our farm’s terrain is high around the edges and low in the middle. Although there are drainage channels nearby, they have been left unmaintained and are almost completely derelict, with no connection to the surrounding waterways. No matter how deep we dig our own drains, it makes no difference — the water simply floods back into our fields.

So when the problem is this big and structural, a single farm or farmer can hardly tackle it alone. This year we again put our own money towards clearing the public drainage channels, and we are also exploring ways to work with neighbouring farms to find a solution together.

● We even dig drainage channels inside the polytunnels to guard against flooding.

III. How the Farm Responds

Having shared the farm’s difficulties, let me now talk about some distinctive strategies we have developed over the past few years.In 2021, sustained rainfall caused the earthen walls of some of our polytunnels to slump and partially collapse, but the damage was not severe. This was thanks to a thick growth of weeds on the earthen slopes behind them, whose root systems anchored the soil. Otherwise those polytunnels could have suffered far worse collapses, and the entire year’s work would have gone to waste.

In the past, we considered all that grass a safety risk — dry in winter and prone to catching fire — so we covered the slopes with plastic sheeting to keep grass from growing there. But as rainfall has increased over the past few years, the advantage of maintaining grass to stabilise the slopes has become clear. Our earthen walls are still so thick, however, that the grass roots have not yet penetrated them. I hope, over time, to coax those roots deeper.

Similarly, on bare ground where no crops are grown, we are also sowing grass. The ryegrass mentioned in Foodthink’s regenerative agriculture talk — this past winter, we tried growing it in the open field, not to harvest it, but to let its roots protect the soil. Because frequent cultivation does great harm to the soil, this year we are also experimenting with no-till cultivation.

Past Articles▼

These are the polytunnels at our farm in Lingqiu, Shanxi. Inside them, we have been trying to grow Cnidium monnieri and other companion plants. Because insects are extremely sensitive to temperature, climate change can easily trigger unexpected pest outbreaks. We hope these plants will create a suitable habitat for natural enemies of pests, helping to keep infestations in check.

We also grow aubergines inside the polytunnels. The dense foliage of aubergines creates a sheltered, enclosed environment where insects that are sensitive to disturbance can settle, forming a welcoming habitat for natural enemies. The aubergines in this photo grew continuously from December 2021 to December 2022. Over that year, we found a rich population of aphid wasps, hoverflies and green lacewings, among other beneficial insects. Once the aubergines are established, I no longer worry about pests such as aphids.

In the past, growing cucumbers inside the polytunnels meant a headache from aphids every single year. To cope, we always planted and harvested quickly, keeping cucumber seedlings on standby so that we could replant as soon as aphids devastated a batch.

But last year we tried a new approach: we planted chillies and aubergines first, letting the aphids feed on them before the cucumbers went in. Aubergines and chillies branch readily and regenerate quickly. Before long, natural enemies of aphids appeared on their own, without any artificial introduction. By that point, I could plant cucumbers alongside them with confidence.

These natural enemies keep aphids in check, though they do not eliminate them entirely. But thanks to them, aphid populations stay under control and never cause serious harm. Free from aphid interference, the cucumbers can fruit from December all the way through to July.

Next, we plan to try intercropping aubergines with Cnidium monnieri and pyrethrum — plants well suited to supporting natural enemies.

● Fermented plant extract the farm makes from tomatoes.
The farm also makes several types of biofertiliser ourselves: fermented plant extracts, Bacillus subtilis cultured through hay fermentation, and fermented compost. After a flood, they prove invaluable. Soil naturally harbours a vast community of microorganisms. On our organic farm in particular, high levels of organic matter mean microbial diversity is even greater. These microorganisms are the key to soil health. Flooding, however, destroys the existing balance of the soil ecosystem: beneficial bacteria die off and harmful anaerobic bacteria take over. That is why planting seedlings immediately after the water recedes rarely succeeds. Just as disaster zones need to be sprayed with disinfectant after a flood, the soil too needs to be sanitised. So we generally turn the soil after the water recedes and leave it exposed to the sun for a period of time. Adding large quantities of these biofertilisers at that stage helps beneficial bacteria multiply rapidly and restores the microbial community to normal.

IV. Flexibility and Diversity

In truth, our farm has many more strategies for adapting. But for a farm practising organic farming, the most important thing remains raising biodiversity and building a more stable ecosystem. To take the simplest example, our farm grows over a hundred varieties of vegetables throughout the year, with several dozen in cultivation at any given time. They respond differently to the climate, so even when the weather shifts, the losses are never total. When the climate’s character changes, we are flexible enough to try new varieties and growing methods. This is precisely what The Earth Doesn’t Care states: in the face of climate change, enriching the diversity of each agricultural ecosystem within a region enhances its stability. Only by linking these smaller ecosystems together can we strengthen the resilience of the larger system against climate risk.

Flexible, diversified agriculture will surely prove its worth in the face of climate change.

Unless otherwise credited, all images courtesy of the author

Text compiled by: Wan Lin

Edited by: Wang Hao

Published by Foodthink