{"id":5434,"date":"2026-08-30T10:43:12","date_gmt":"2026-08-30T08:43:12","guid":{"rendered":"https:\/\/www.permatechnics.com\/heatwave-and-drought-in-market-gardening-6-concrete-tips-to-protect-your-crops\/"},"modified":"2026-09-15T12:35:43","modified_gmt":"2026-09-15T10:35:43","slug":"heatwave-and-drought-in-market-gardening-6-concrete-tips-to-protect-your-crops","status":"publish","type":"post","link":"https:\/\/www.permatechnics.com\/en\/heatwave-and-drought-in-market-gardening-6-concrete-tips-to-protect-your-crops\/","title":{"rendered":"Heatwave and drought in market gardening: 6 concrete tips to protect your crops"},"content":{"rendered":"

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The summer of 2026 was a reminder of something market gardeners already know in the field: heat and lack of water do not only disturb the crops. They also disrupt sowing, transplanting, irrigation, harvesting, bed occupancy and, at the end of the chain, sales.<\/p>\n

In Wallonia, the authorities kept a high level of vigilance on the water resource<\/a> through the summer of 2026, with restrictions on use in several municipalities. Looking further ahead, the Walloon agriculture portal<\/a> points out that the prolonged droughts of 2017, 2018, 2019, 2020 and 2022 severely affected farms, and that climate projections indicate a growing risk of spring and summer droughts. So the problem is no longer just saving a crop through three days of heatwave: decisions have to be taken earlier, levers have to be combined, and replanning is needed when the season goes off the rails.<\/p>\n

No single technique is enough on its own. Irrigation, mulching, shading, variety choice, soil quality and adapting the calendar work above all when they are used at the right moment.<\/p>\n\n\n\n\n\n\n\n\n\n
\n

Lever<\/b><\/p>\n<\/td>\n

\n

When to decide?<\/b><\/p>\n<\/td>\n

\n

Effect sought<\/b><\/p>\n<\/td>\n<\/tr>\n

\n

Localised, monitored irrigation<\/p>\n<\/td>\n

\n

When the crop goes in, then week by week<\/p>\n<\/td>\n

\n

Put the water in the right place at the right time<\/p>\n<\/td>\n<\/tr>\n

\n

Mulching<\/p>\n<\/td>\n

\n

Early in the season, on soil that is damp enough<\/p>\n<\/td>\n

\n

Limit evaporation and protect the soil surface<\/p>\n<\/td>\n<\/tr>\n

\n

Shading and ventilation<\/p>\n<\/td>\n

\n

Before the forecast peak of heat<\/p>\n<\/td>\n

\n

Reduce heat stress and scorch<\/p>\n<\/td>\n<\/tr>\n

\n

Variety choice<\/p>\n<\/td>\n

\n

When ordering seed<\/p>\n<\/td>\n

\n

Secure the series exposed to high temperatures<\/p>\n<\/td>\n<\/tr>\n

\n

Soil structure and cover<\/p>\n<\/td>\n

\n

Continuously, over several seasons<\/p>\n<\/td>\n

\n

Increase the soil’s capacity to buffer swings in water supply<\/p>\n<\/td>\n<\/tr>\n

\n

Shifting the calendar<\/p>\n<\/td>\n

\n

Before or during the risk episode<\/p>\n<\/td>\n

\n

Stop a sensitive stage falling in the wrong weather window<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

What heat and lack of water actually do to crops<\/b><\/h3>\n

When soil dries out, the plant has less water to feed its tissues and keep transpiring. It gradually closes its stomata to limit losses. That is an effective survival reaction, but it also reduces gas exchange and slows photosynthesis. Growth, the swelling of the harvested organs and sometimes fertilisation can then suffer.<\/p>\n

The symptoms depend on the crop and the stage: accelerated bolting on some lettuces, spinach or radishes, poor fruit set and flower drop on fruiting vegetables, wilting, leaf scorch or uneven sizing. The stress becomes particularly damaging when it happens during establishment, flowering, fertilisation or swelling.<\/p>\n

The Centre wallon de Recherches agronomiques<\/a> lists water and heat stress, the depletion of soil water reserves and the acceleration of phenology among the significant consequences of climate change. In diversified market gardening, short cycles leave little room: a week lost on one series can quickly carry over to the next.<\/p>\n

1. Irrigation: get the monitoring right before looking for the perfect kit<\/b><\/h3>\n

Drip irrigation is often presented as the obvious way to save water. It can indeed perform very well, but the universal figure of “50% saving” is too simplistic.<\/p>\n

The report “Agro\u00e9cologie et besoins en eau” from the Office fran\u00e7ais de la biodiversit\u00e9<\/a> draws on IRSTEA and SOLAGRO reference figures estimating a potential saving of 17 to 43%, with no significant loss of yield, when moving from sprinkler to drip irrigation in market gardening. For the use of monitoring sensors, the range quoted rises to 45 to 50%. The same report makes clear, however, that these results vary according to the crop, the stage, the soil, the practices, network losses and the climate of the year. It even cites a group of market gardeners and fruit growers who ended up dropping drip irrigation in favour of sprinklers and porous hose, better suited to their situation.<\/p>\n

The lesson is simple: the best system is the one you know how to run properly in your own soil and for your own crops.<\/p>\n

Tensiometer probes and other decision support tools, whose use is documented by the Chambre d’agriculture de Bretagne<\/a>, can help trigger irrigation at the right moment and avoid over-watering. As a general benchmark, 20 to 50 cb corresponds to a comfortable water range. The Watermark handbook from Challenge Agriculture<\/a> then gives, as general benchmarks not specific to market gardening, average trigger points of around 40 cb in sandy soil, 70 cb in silty soil and 90 cb in clay soil. These values are not universal thresholds: they have to be recalibrated against the crop, the stage, the rooting depth, the actual soil texture and the measuring equipment.<\/p>\n

Check the restrictions before building the irrigation programme<\/b><\/h3>\n

The right to use water can change during the season. In France, as the ministry for the ecological transition<\/a> points out, measures run from vigilance to crisis level and can limit irrigation hours or certain abstractions; the applicable orders can be checked on VigiEau<\/a>. In Wallonia, the framework also depends on the type of abstraction point: a groundwater or surface abstraction point is subject, depending on its class, to an environmental permit or to a declaration. For farms that take water outside the public supply, the volumes used have to be declared to SPW ARNE<\/a> by 31 March. So you need to check the resource used, the regime of the abstraction point and any local restrictions.<\/p>\n

2. Mulch, but at the right moment and at the right thickness<\/b><\/h3>\n

Mulching reduces direct radiation on the soil, slows the drying of its surface, limits the effect of wind and can slow run-off during a storm. In market gardening it is therefore a useful lever both during dry spells and when heavy rain returns.<\/p>\n

But a mulch is not automatically beneficial. Laid on soil that is already very dry, it can simply lock in a poor water situation. Ideally it goes on soil that is still damp, or after watering that recharges the worked layer.<\/p>\n

Thickness depends on the material. For a thick plant based mulch, around 10 cm is a common benchmark, without being a universal rule. The trade-offs also have to be taken into account: cost, handling, potential shelter for slugs or rodents, and difficulty establishing the following crop if the material breaks down poorly. Mulching therefore remains a tool to be adapted to the system, not a universal rule.<\/p>\n

3. Shading and ventilation: act before the greenhouse turns into an oven<\/b><\/h3>\n

Under a polytunnel or a greenhouse, the first lever against a peak of heat is often ventilation. Opening the doors wide enough, rolling up the sides where the structure allows it and anticipating the rise in temperature all prevent a build-up of heat that is then hard to shift. The practical objective, documented by Bio en Normandie<\/a>, is to stay as far as possible below 30 to 35\u00b0C: above that, on tomato, pollen quality degrades, fruit set becomes more difficult and bumblebee activity drops.<\/p>\n

Shading comes on top of that. Nets, screens or whitewash can reduce the radiation reaching the crops; under cover, figures of around 30 to 40% shading are a technical benchmark. That level still has to be adapted to the crop, the light levels and the period: too much shade can penalise photosynthesis, earliness and the behaviour of pollinators.<\/p>\n

These protections are particularly worthwhile for young plants recently transplanted and for crops prone to bolting or scorch. Ideally they should be installed before the forecast peak, not once the damage is already visible.<\/p>\n

Over the longer term, hedges and agroforestry systems can change the microclimate, but they involve trade-offs on light, water, nutrients, spacing and upkeep. That lever is planned over several years.<\/p>\n

4. Variety choice and calendar: prepare for the heatwave months before summer<\/b><\/h3>\n

A variety reputed to tolerate heat, water stress or bolting does not remove the need for water. It can, on the other hand, hold its quality or its yield better in certain difficult conditions.<\/p>\n

That is particularly worthwhile for crops where quality is lost quickly and is hard to recover, such as some lettuces, spinach or radishes. The mistake is to discover how varieties perform at the moment the heatwave arrives.<\/p>\n

The choice is prepared when you order your seed. Test a few varieties on small areas and record the dates of sowing, transplanting, harvest, bolting and commercial losses. After a few seasons, the farm builds its own reference figures.<\/p>\n

The calendar counts as much as the genetics. Shifting a series by a few days can sometimes keep establishment after transplanting, flowering or another sensitive stage out of the hottest window.<\/p>\n

5. Build a soil that buffers dry spells better<\/b><\/h3>\n

A soil in good structural condition does not create water, but it can take in rain better, limit run-off and store part of the water available to plants. INRAE<\/a> points out that the soil’s available water capacity and how it functions are central elements of agricultural drought.<\/p>\n

Several levers contribute to it: keeping the soil covered where the system allows, limiting compaction, encouraging a stable structure and adding suitable organic matter. Cover crops do need managing, though: they protect the soil but they also use water. In a deficit situation, the date on which they are destroyed becomes a genuine water management parameter.<\/p>\n

This is the slowest lever in this article: it is built over several seasons. It is also the one that can improve the farm’s resilience against both extremes, drought and heavy rain.<\/p>\n

6. Replanning a series: the free lever that avoids the domino effect<\/strong><\/h3>\n

The most underrated technique needs no pump, no net and no tonne of mulch: it consists of changing the calendar before a bad weather window costs you a series.<\/p>\n

Take a classic situation. A heatwave lasting several days is forecast and your lettuce plants are ready to be transplanted. Waiting ten days is not necessarily possible: the plants can age in the propagation area, grow leggy or become more prone to bolting. The right call may be to go ahead with transplanting under protection, with suitable establishment watering, while shifting the following series.<\/p>\n

But moving one date never moves only one date.<\/p>\n

The next sowing moves. The transplanting moves. The weeding and monitoring operations follow. The harvest slides, sometimes by a different interval because growth rate changes with the season. The bed comes free later. The following crop is affected. The workload is distorted and the volumes available to sell can leave a gap in the veg boxes, the AMAP scheme or the market stall.<\/p>\n

On one crop, that cascade stays manageable. On fifteen crops and several dozen series, it no longer is. A notebook quickly becomes wrong and a spreadsheet requires the dependencies to be redone by hand. PermaTechnics addresses exactly that problem: when a planting or propagation date is changed, the tasks tied to the crop protocol can be realigned around that new reference, without moving what has already been done. In practice, the market gardener sees immediately how that shift carries over to the tasks, the workload and bed occupancy, without going through every line of a spreadsheet.<\/p>\n

Obviously that does not make it rain and it replaces neither good irrigation nor a well managed soil. The value lies elsewhere: avoiding the second loss, the one that comes when a weather event turns into an organisational problem.<\/p>\n

What to do now, and what to do this winter?<\/b><\/h3>\n

Separating decisions by time horizon avoids dealing with everything in a rush.<\/p>\n

Today and in the next few days: check the actual water status, secure young plantings, open up the tunnels, check the network, install shading before the peak and decide which series should be kept and which should be shifted.<\/p>\n

After the season and during the winter: compare the varieties, the beds that struggled, the yields and the dates actually achieved; then adapt the seed orders, the production windows, the sizing of the irrigation and the flexibility of the crop plan.<\/p>\n

The data to keep so you can decide better next year<\/b><\/h3>\n

A difficult season becomes useful if it leaves behind information you can work with. Five pieces of data are already enough to improve decisions:<\/p>\n

    \n
  1. The dates actually achieved: sowing, transplanting, start and end of harvest.<\/li>\n
  2. The series that suffered bolting, scorch, flower abortion or loss of size, with the variety and the stage.<\/li>\n
  3. The irrigation calls: which beds were given priority and with what result.<\/li>\n
  4. The yields or volumes actually harvested on the series affected.<\/li>\n
  5. The changes made to the schedule and their consequences for the following crop and for the workload.<\/li>\n<\/ol>\n

    With two or three years of consistent data, an impression gradually becomes a farm reference. You know which series regularly struggle, which varieties are worth keeping and which periods should be avoided or secured.<\/p>\n

    Frequently asked questions<\/b><\/h3>\n

    When should you water during a heatwave?<\/b><\/p>\n

    There is no ideal time that suits every system. With sprinklers, cooler periods generally limit evaporation losses, and you also have to take into account how long the foliage stays wet and the disease risk that comes with it. With drip irrigation, the choice of time is often less decisive than the dose, the duration and the actual water status of the root zone.<\/p>\n

    Is drip irrigation always more economical than sprinklers?<\/b><\/p>\n

    No. The reference figures compiled by the OFB<\/a> indicate significant saving potential in market gardening, but the results depend heavily on the situation. A drip system that is badly sized or badly managed can be less relevant than another system properly matched to the soil and the crop.<\/p>\n

    What thickness of mulch should you apply?<\/b><\/p>\n

    There is no universal thickness for every material. For a thick plant based mulch such as straw, around 10 cm is a common benchmark. The aim above all is to get a cover dense and durable enough without hampering the crop or making the rest of the rotation unduly complicated.<\/p>\n

    Can you irrigate during a drought restriction?<\/b><\/p>\n

    That depends on the country, the level of restriction, the resource used and the local order. In France, VigiEau<\/a> lets you consult the applicable measures. In Wallonia, you have to check municipal decisions and any measures concerning abstractions. Never build an irrigation plan on a general rule found in an article.<\/p>\n

    Which lever should you start with if nothing is in place yet?<\/b><\/p>\n

    Start with what can be decided immediately: secure the sensitive stages, correct the calendar and improve the way the available water is managed. Mulching and shading can follow quickly. Variety choice, soil improvement and irrigation investment are then prepared for the following seasons.<\/h6>\n

    What to take away<\/b><\/h3>\n

    Heatwave and drought are managed less by a single recipe than by the quality of the decisions: knowing when to irrigate, when to protect, when to shift a series and which information to keep for the following season.<\/p>\n

    The real issue is stopping a few days of weather disorganising the series that come after it.<\/p>\n

    PermaTechnics is built for diversified market garden farms that have to manage these dependencies day to day. To see concretely how to shift a crop without redoing by hand the whole schedule that depends on it, a demonstration lets you start straight from a real planning case.<\/p>\n

    Main sources<\/b><\/h3>\n