Eating local and seasonal is one of the recommended measures for a sustainable diet. For those who stick to it, the arrival of strawberries on the stalls, a sign of spring, is eagerly awaited. But these often precede the official season by a month, which runs from May to July. A few questions then arise: were these first strawberries grown in the ground or above ground (hanging vegetable gardens, hydroponics, aeroponics, etc.)? Were they heated in a greenhouse to mature earlier? Apart from the origin and the method of cultivation (conventional or organic), the information lacks transparency. But by looking at the specifications of the different labels (see box), it is possible to find out more.
An impact that goes from simple to triple
Having this information is important in terms of environmental impact: 1 kg of seasonal strawberries (purchased between May and July, therefore) corresponds to an emission of 477 g of CO equivalent2, compared to 550 g for 1 kg of strawberries consumed out of season, according to the Agribalyse database (1). In both cases, culture alone represents 84% of emissions. And for good reason: greenhouse heating relies mainly on fossil fuels. 60 to 77% of heated surfaces are heated using natural gas. So, “the environmental impact of strawberries in heated greenhouses in France is three times greater than that of strawberries in the open field or under shelter in the ground”, illustrates the Ecological Transition Agency (Ademe). If we focus on greenhouse gas emissions, this impact is 3 to 10 times greater.
The use of a closed shelter or above-ground cultivation poses other environmental problems: in addition to the biological impoverishment of the soil, it is impermeable – which encourages the runoff of water, which is normally absorbed. Which is not negligible, given that 55% of production is done above ground – including 20% in a heated greenhouse.
We could therefore think that a fruit coming from Spain, but not having been heated, would be preferable to a fruit heated in France. It is a mistake. Transport relies on fossil fuels and represents 15% of the impact of a strawberry. Furthermore, water scarcity profoundly modifies the environmental impact. “Taking a liter in Spain or Morocco, where water is rarer, will have more impact than in Brittany”, explains Ademe. The ideal therefore remains to consume both local and seasonal.
What are the labels worth?
Labels that guarantee nothing
A true paradox, and much criticized, the HVE (High Environmental Value) label accepts crops under heated shelters and above ground.
The same goes for Label rouge strawberries, whose origin is still limited to the Dordogne and Lot-et-Garonne. As for the AOPn (Association of National Producer Organizations) Fraises de France, two-thirds of its production is done above ground.
Labels that guarantee cultivation in the open ground
The specifications for organic farming are clear: above-ground farming is prohibited. On the other hand, the use of heated greenhouses has been permitted again since 2023. A tolerance which seems to contradict several principles laid down in the specifications, such as “respect for natural cycles” and an “responsible use of energy”. Please note that this label guarantees the absence of chemical pesticides.
The Strawberry of Périgord protected geographical indication (PGI) has the merit of requiring cultivation in the open ground and picking of the fruit when ripe. However, it does not prohibit the use of heated shelters.
The prize for transparency goes to the Nature et Progrès mention. Cultivation in greenhouses, heated or not, is tolerated but must be clearly indicated on the labeling.
Labels that guarantee cultivation in the ground and the absence of heating
Some specifications are more demanding towards producers, banning both above-ground cultivation and heated greenhouses. The only exception allowed by Demeter and Bio Cohérence: heating intended to protect crops from frost when it is below 5°C. This must remain the exception to obtain the Bio Cohérence label, which limits this heating to 10 days per calendar year.
The Strawberry of Nîmes protected geographical indication (PGI) is also rigorous: the specifications require cultivation in open ground and authorize shelter. This can be closed, but not heated.
An impact to put into perspective
Consuming a strawberry out of season increases its environmental impact significantly. But we must keep in mind that this impact remains low compared to that caused by animal products. These represent 50% of the diet, but 88% of its carbon footprint! For comparison, 1 kg of seasonal strawberries corresponds to 0.07 meals with beef in terms of CO equivalent2.
(1) Agribalyse is a database managed by Ademe. It concentrates data on the environmental impact of agricultural and food products in France. Here, the calculation takes into account the different methods of strawberry production and their proportion.
