Concept visual: Wild Bite Club.
At one Berlin REWE, lettuce now travels down before it travels across the city. The rooftop farm turns supermarket real estate into supplier, proof point and retail theatre.
On a produce shelf in Berlin-Lankwitz, a 100-gram bag of mixed lettuce carries a supply-chain claim that is unusually literal. The leaves were not trucked in from a rural greenhouse or imported from southern Europe. They grew a few metres above the shopper, inside a glass farm built on the supermarket roof.
The first “Lankwitzer Pflücksalat” was harvested in August at a REWE market on Malteserstrasse. The mix—Batavia, green romaine, Lollo Rosso and dark-green Easy Leaf—moves from trays to processing, packaging and sale within the same building. Some bags stay downstairs; others enter REWE’s regional distribution network and reach roughly 500 stores in eastern Germany. The striking part is not simply local lettuce. It is that a retailer has turned its own real estate into part of the food-production system.
The roof became a supplier
REWE opened the market on 21 May 2026, then brought the rooftop farm into operation on 7 August. The 2,760-square-metre greenhouse is operated by Berlin-based ECF Farmsystems. Plants travel through an automated hydroponic system on specialised trays, receive nutrient solution several times a day and are irrigated with rainwater collected in a roof cistern. The growing cycle takes 23 days. At planned capacity, the farm can produce up to 900,000 salad mixes a year.
This is a production site attached to a normal supermarket, not a demonstration garden. Four ECF employees oversee the greenhouse seven days a week, and harvesting takes place on six. A packaging machine sits in the back-of-house area. REWE says part of the output goes directly to the store and the rest through its Oranienburg regional warehouse; compared with imported produce from southern Europe, the company estimates that the arrangement could avoid about 500,000 transport kilometres.
The distinction matters. Many urban-farming projects make their strongest impression at the point of cultivation, then struggle with the less photogenic work of packing, selling and moving the crop. Here the buyer, shelf space and logistics network were designed into the project. ECF’s own business model describes precisely that division: the farm specialist plans and operates production while the retail partner finances the site, buys the crop and handles sales.
A supermarket designed around the claim
The building does not hide the farm as a technical unit. ACME, the architecture practice behind the project, designed a timber market hall with a greenhouse visibly sitting above it. Inside, 72 columns made from stacked timber create a high, bright hall. Glazing and skylights connect the retail floor to the cultivation space overhead. The architecture turns “grown here” from a label into something shoppers can understand spatially.
That gives REWE a form of differentiation private-label packaging alone cannot create. A competitor can copy a salad recipe or put a regional story on a bag; it cannot quickly reproduce a greenhouse integrated into the building, the distribution system and the customer experience. The farm functions simultaneously as supplier, proof point and store theatre—although the production rooms themselves remain closed to the public for hygiene and crop protection.
There is precedent. REWE and ECF opened their first Green Farming supermarket in Wiesbaden-Erbenheim in 2021, where basil was grown on the roof alongside aquaculture. Berlin is the second version and a more standardisable one. The building uses modular timber components, and REWE says the format will now move into series production with different roof uses adapted to different sites. The commercial experiment is therefore larger than one crop: can a supermarket become a repeatable platform for food production as well as food retail?
Why lettuce works upstairs
Lettuce is a rational test crop. It is light, fast-growing, perishable and visually legible. Its quality deteriorates as time passes, so shortening the interval between harvest and shelf has an obvious consumer benefit. It also fits hydroponic production better than bulky or slow-growing foods. Nobody should read 900,000 salad bags as evidence that rooftops can replace rural agriculture; the significance lies in matching a constrained urban site to a crop where freshness and transport matter disproportionately.
The wider potential is real but easy to inflate. A 2026 study in Sustainable Cities and Society assessed rooftop and ground-level growing space across 840 European cities. Under its scenarios, urban agriculture could supply up to about 28% of vegetable demand for 190 million residents. But the paper modelled low-tech, open-air, soil-based production, not a climate-controlled retail greenhouse. Its authors emphasise variation by urban form, available land and climate. Berlin’s roof is one commercial answer, not a universal template.
The carbon story is not automatic
Shorter transport is the easiest benefit to communicate, but it is not the whole environmental balance. A rooftop greenhouse requires steel, glass, pumps, controls, labour and heat. Its advantage depends on how those inputs are supplied and whether the building creates genuine synergies. REWE says the Lankwitz site uses waste heat from refrigeration, a heat pump, collected rainwater, around 200 solar modules and renewable electricity. Those integrations are important because they allow the farm to use flows that already exist around the store.
Even so, company estimates are not a full life-cycle assessment. Avoided truck kilometres do not by themselves prove a lower footprint per bag. Yield, winter heating, packaging, electricity, rejected crops and construction all matter. The strongest case for the model may ultimately be operational rather than symbolic: stable year-round output close to demand, less exposure to long transport routes, and a retail system able to sell almost immediately after harvest.
There is also a scale complication. The local story weakens slightly when most output leaves the building through a conventional regional warehouse. That is not a failure; it is how a 2,760-square-metre farm becomes more than an expensive amenity for one neighbourhood. But it reveals the central tension. “From the roof” is intimate marketing. Supplying 500 stores is a network business. The project succeeds commercially only if it can do both without allowing the story to outrun the logistics.
What is visible, and what is still emerging
Observed: the Berlin market is open, the farm began harvesting in August, the lettuce is on sale, and output is being distributed beyond the host store. The production system, staffing, crop cycle and planned capacity are documented by REWE, ECF and the project architect. Shoppers can see the physical relationship between the market and the greenhouse, even though they cannot enter the growing area.
Emerging: supermarket property is being treated as productive infrastructure. The relevant signal is not that every roof will grow lettuce, but that retailers can combine unused space, waste heat, water capture, purchasing commitments and existing logistics into a new supplier model. REWE’s move from a 2021 pilot to a second, modular site suggests the company sees a format worth repeating, though economics at wider scale have not been disclosed.
Possible next step: retailers could choose roof uses crop by crop and city by city rather than copying one greenhouse. A dense urban store might grow high-value herbs; another site might prioritise solar power, housing or water retention. Production data could also feed directly into promotions and replenishment, turning a 23-day crop cycle into a planning input. These are WBC interpretations, not announced REWE features.
The shelf is becoming part of the farm
Berlin’s rooftop lettuce is commercially interesting because it collapses three functions that food retail normally keeps separate: production, distribution and merchandising. The bag on the shelf is both a product and evidence of how the building works.
The opportunity for retailers is not “urban farming” in the abstract. It is the ability to secure a perishable product, make freshness visible and turn a fixed property cost into productive capacity. The risk is spending heavily on an architectural sustainability claim that never reaches competitive economics. The winners will be the projects where the farm is not decoration above the store, but a supplier designed into the business below.