A REWE supermarket in Lankwitz, Berlin, has begun selling lettuce grown in a rooftop greenhouse directly above the shop floor, making it Germany's largest rooftop farm at 2,760 square metres. The "Lankwitz loose-leaf lettuce" is harvested and packaged within metres of where it is sold, cutting out the transport typically needed to move produce from farm to distribution centre to store, while also reducing emissions and easing the urban heat effect associated with bare rooftops.

The greenhouse, run by Berlin-based agri-tech firm ECF in partnership with REWE, grows lettuce hydroponically with minimal soil, with each crop taking just over three weeks to mature. It is heated using waste heat from the store's cooling systems below and relies mainly on rainwater and solar power, with skylights letting shoppers see the crops growing overhead. Store manager Felix Thomas said one customer travelled more than 50km for a bag, though researchers caution that such commercial rooftop farms, while promising for shortening supply chains, should complement rather than replace community-based urban gardening.