Tough Celery: Is Climate Change Really to Blame?

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Foodthink Says

How exactly is agriculture being shaped by climate change? Foodthink has already published a series of articles exploring this question. Today, we share insights from a grower working on the front lines. Zhao Fei graduated from the College of Agronomy at China Agricultural University before joining Pingren Farm, an organic operation where he manages vegetable production across two sites: Changping in Beijing and Lingqiu in Shanxi. On 8 January, alongside two fellow ecological farmers, he joined a climate change discussion at the Fengnian Harvest Festival in Beijing. Using everyday vegetables as examples, Zhao Fei explained how extreme weather impacts farming and outlined the unique adaptation strategies the farm has put in place.

This article is adapted from his talk. We hope these vivid examples will help you better grasp the intricate interplay between farmers, crops, and the weather.

Click the link below to watch the full replay of the session.

On the farm, we are frequently asked by consumers: Why do the vegetables look like this? Why has it gone tough? Why is it so sweet? Why are there insect holes?

More often than not, the answer lies in the weather. As climate change intensifies, everyday consumers can now feel its effects directly through the food on their plates.

● A thriving strawberry patch, autumn 2022. Xingshou Town in Changping, where Pingren Farm is based, is Beijing’s main strawberry-growing region.

Let us begin with strawberries, which are currently in season. Unseasonably warm temperatures in October 2022 spurred vigorous growth. Yet this was far from ideal, as the plants prioritised foliage over flowering. As a result, the overall market window for strawberries was delayed, shifting from December last year to January this year.

The broccoli we cultivated in Changping during spring 2022 grew prematurely old and yellowed under the sun, and neighbouring farmers faced similarly poor conditions compared to previous years. We had long worried about temperatures dropping too low, but last year they were conversely too high. Just a few unseasonal heat spikes were enough to bleach the broccoli heads.

Consumers who brought such broccoli home would notice a thicker layer of ‘waxy bloom’ on the leaves than usual. This is the plant’s natural defence mechanism, shielding itself from intense solar radiation and preventing dehydration under high temperatures.

● Lingqiu, Shanxi: open-field celery affected by leaf spot disease.
Customers who purchased celery from our farm last year would attest to this. The variety, known as “French Queen”, is typically succulent and crisp. Yet last year’s high temperatures and humidity triggered excessive fibrous growth, rendering the stalks stringy and tough. Such conditions also left cool-weather celery highly vulnerable to disease. Severe leaf spot outbreaks wiped out several successive crops. Even when harvests were salvageable, the foliage was so compromised that it had to be stripped out before sale, leaving consumers with little more than bare stalks.

I. “Unpredictable Seasons”: Farming by the Weather Is No Longer Viable

We often hear the saying that ‘farming is at the mercy of the weather’. Many take this to mean that natural disasters are commonplace, leaving harvests highly vulnerable to droughts and floods. Yet the phrase originally conveys something quite different: agriculture thrives on the predictable rhythms of nature, summed up in the classical notion that ‘the earth observes its cycles, and the four seasons never stray from their course’. It is only by recognising stable local climate patterns that farmers can plan their production. When I first arrived to work at the farm in Lingqiu, Shanxi, my first port of call was the local agricultural supply shops. Through conversation, I gained a feel for the area’s weather patterns. Cross-referencing this with recent historical data on average and extreme temperatures, rainfall, and other meteorological indicators allowed me to draft a broad production calendar: identifying the optimal windows for sowing specific crops, foreseeing potential climate-related hazards, and preparing the necessary safeguards. Time spent learning from seasoned local growers also sheds light on regional cultivation habits. Much of this accumulated wisdom has been distilled into local farming proverbs. For instance, at our farm in Xingshou, Changping, just outside Beijing, we traditionally sow peas around the *Jingzhe* (Awakening of Insects) solar term. In old Beijing parlance, this follows the rule that ‘peas must be sown before the nine nines end’—meaning they must go into the ground before the traditional 81-day winter count concludes. These sayings capture the ideal temperature and season for pea cultivation as identified by generations of growers. If the conditions are too warm or too cold, the crop’s development will be compromised.

● Local farmers typically sow Chinese cabbage around the autumn equinox and transplant onions around the End of Heat. The planting schedules for these crops have traditionally been quite fixed.

When I was young, my granddad often said to me: “Rain on the twenty-fifth of the lunar month means the following month’s soil won’t dry out.” It is a traditional farming rhyme from Anhui, my home province, meaning that if the twenty-fifth day of the lunar calendar sees rain, continuous downpours will follow into the next month. “Gloomy skies at Grain Rain, drenching rains at Start of Summer”—wet weather during the Grain Rain period promises another 45 days of heavy rainfall. These are all rules of thumb distilled from generations of observing seasonal weather patterns.

These days, there’s much debate over whether climate change will ultimately benefit or harm farming across different regions. Yet, regardless of the outcome, once weather patterns become erratic and unpredictable, generations of hard-won agricultural experience will be severely tested. For now, we can only navigate by trial and error, learning to read the new rhythms as we go.

● This carrot grew rather poorly. The unseasonably warm temperatures caused the foliage to senesce early, leaving the roots underdeveloped and misshapen.
● The young brassicas grown in open fields this early spring have been riddled with holes by yellowstriped flea beetles. The plan was to sow early and harvest before the pests became active, but the mild winter allowed them to emerge well ahead of schedule.
● Climate change can also bring unexpected silver linings. The unseasonably warm weather in Lingqiu, Shanxi, this year curbed late blight in tomatoes, leading to a bumper harvest for local growers! Yet, as reports indicate, a nationwide glut has suppressed farm-gate prices. In some regions, the price has fallen to as low as 0.30 yuan per jin (half a kilogram), reviving the age-old dilemma of “a bumper crop leaving farmers poorer than before.”

II. Extreme Weather Disasters

Climate change has also brought with it even more severe weather disasters. The traditional slate of agricultural hazards—frost, snow, rain, hail, drought, flooding, pests, and diseases—has become harder to predict and far more frequent. On 4 May 2021, Changping in Beijing experienced a highly unusual frost. Meanwhile, heavy snow fell in Lingqiu, Shanxi province, during May. Mr Song, a local man in his sixties who works on the farm, remarked that heavy snowfall in May is genuinely rare. That spring, ground temperatures were unusually low, forcing all planting schedules to be delayed. It leaves you wondering: is the climate actually warming or cooling? The reality is simply that the climate has grown erratic, making extreme weather increasingly common.

●A scene of the farm’s greenhouses being flooded in 2018.

Before I came to Pingren Farm, it hadn’t been flooded by rain in seven years. But since I arrived, it’s been flooded three or four times. At the worst, almost the entire farm was submerged.

●Winter 2021: heavy snowfall overnight collapsed several greenhouses. The women who work on the farm reflected that they hadn’t seen snow this heavy in a long time.
●In 2021, we also faced wind damage, with stronger and longer-lasting winds than in previous years. The plastic sheeting of almost every greenhouse was torn off by the storm.

Minor setbacks, like frost, we can weather by relying on our facilities or simple measures like lighting heating blocks. But a major disaster wipes out a year’s work, or even several years’.

We’ve considered agricultural insurance, but it only covers certain types of damage. For instance, insurance defines rain damage as heavy rain over a short period. The prolonged rainfall in 2021 saturated the soil. Because our land lies low, saline groundwater rose to the surface, causing the topsoil to become saline. Continuous rain also floods the greenhouses and leaves the soil too waterlogged for planting, but none of this falls under the insurance policy.

Given the increase in rainfall, we’ve had to dig drainage ditches every year, making them deeper each time. However, our farm sits in a depression, surrounded by higher ground. Although there are drainage ditches nearby, they’ve been largely neglected due to lack of maintenance and no longer connect to the local rivers. No matter how deep we dig, it’s pointless; it actually causes rainwater to backflow into the fields.

Since these broader environmental issues can’t be solved by one farm or farmer working in isolation, we’ve taken a collaborative approach. This year, we again contributed funds to clear the public drainage ditches, and we’re exploring ways to work together with neighbouring farms to tackle the problem.

●We’ve also dug drainage channels inside the greenhouses to prevent flooding.

III. Farm Adaptation Strategies

Having outlined the farm’s challenges, I should also share some of the distinctive approaches we’ve refined over the years.In 2021, prolonged rainfall triggered minor slips and collapses in some of our earth-sheltered polytunnels. Fortunately, the damage was manageable, largely thanks to the dense growth of wild grasses behind the embankments, whose root systems helped bind the soil. Without them, we could have faced far more severe collapses, and the year’s efforts would have been lost.

We used to consider excessive grass a fire hazard, especially during dry winters, so we would cover the ground with plastic sheeting to suppress growth. However, as rainfall has become more frequent in recent years, the benefits of allowing vegetation to stabilise the slopes have become clear. Our earth walls are still rather thick, and the grass roots have yet to penetrate fully. My aim now is to gradually encourage these root systems to grow deeper.

Likewise, on any bare ground left fallow, we are actively establishing ground cover. This winter, we’re trialling direct-seeded ryegrass—the same variety featured in Foodthink’s regenerative agriculture lecture—not for harvest, but to protect the soil with its root network. Given how intensive tilling can degrade soil structure, we are also experimenting with no-till cultivation methods this year.

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This is our polytunnel in Lingqiu, Shanxi, where we’ve been trialling various herbaceous species, including *Cnidium monnieri*. Insects are highly sensitive to temperature fluctuations, meaning climate change can readily trigger unforeseen pest outbreaks. Our strategy is to cultivate these companion plants to create a favourable habitat for natural predators, thereby keeping pest populations in check.

We’ve also planted aubergines inside the tunnel. Their dense foliage creates a sheltered microclimate that allows disturbance-averse insects to thrive, fostering an ideal environment for beneficial predators. The aubergines pictured grew continuously from December 2021 through to December 2022. Over that year, we observed thriving populations of aphid parasitoid wasps, hoverflies, and lacewings among them. Since introducing the aubergines, I no longer lose sleep over aphid infestations.

In the past, growing cucumbers in the tunnel was a constant headache due to aphids. To manage the infestations, we adopted a quick succession planting approach, keeping spare seedlings on hand to rush into the ground the moment the original crop was decimated.

Last year, we tried a different approach: we first planted a section of chillies and aubergines in the tunnel, allowing the aphids to feed on those crops first. Both aubergines and chillies tend to branch vigorously and regenerate quickly. Before long, natural predators of the aphids established themselves organically, without the need for manual introduction. Only then did I plant the cucumbers alongside them.

These beneficial insects keep the aphid population in check rather than eradicating it entirely. However, their presence ensures that aphids remain at manageable levels without causing significant damage. Free from aphid disruption, our cucumbers have been able to fruit continuously from December right through to July.

Moving forward, we plan to trial intercropping *Cnidium monnieri* and pyrethrum—both excellent at attracting beneficial insects—alongside our aubergines.

● Tomato-based enzyme fertiliser, homemade by the farm.
The farm also produces its own range of microbial fertilisers, including plant enzymes, Bacillus subtilis cultures, and composted manure. They come in particularly handy following flood events. Soil naturally hosts a wide variety of microbial communities. In an organic farm like ours, where organic matter levels are high, these microorganisms thrive. They are essential for maintaining soil health. However, flooding disrupts the natural balance of the soil ecosystem. Beneficial bacteria perish, allowing harmful anaerobic microbes to take over. This is why replanting seedlings immediately after the waters recede rarely succeeds. Just as flood zones require disinfection, the soil needs sanitising too. Once the water has drained, we typically till the land and leave it exposed to the sun for a period. Introducing large quantities of these microbial fertilisers at this stage helps beneficial bacteria multiply rapidly, restoring the natural microbial balance.

IV. Flexibility and Diversity

In fact, our farm employs many other strategies to cope. For an organic farm like ours, however, the priority remains boosting biodiversity and cultivating a more resilient ecosystem. To give a simple example: we grow over 100 varieties of vegetables throughout the year, with dozens cultivated simultaneously. Each responds differently to climatic shifts, so fluctuations in the weather won’t wipe out the entire crop at once. When climatic patterns change, we retain the agility to trial new cultivars and adjust our cultivation methods accordingly. As noted in The Earth Doesn’t Care: Confronted with climate change, boosting the richness of agricultural ecosystems within each area enhances their stability. By linking these smaller ecosystems together, we can bolster the resilience of the broader system against climate-related risks.

Flexible and diverse farming will undoubtedly prove its worth in the face of a changing climate.

Unless otherwise stated, all images are courtesy of the author

Compiled by: Wan Lin

Editor: Wang Hao

Published by Foodthink