On a Saturday afternoon in late April, Helga Niemann is kneeling between rows of broad beans in plot 47 of Kleingartenverein Bornkampsweg, a colony of 120 allotments tucked behind a residential block in Bahrenfeld. She has tended this patch of land since 1998. The rent is 280 euros a year. She grows potatoes, tomatoes, courgettes, herbs, strawberries and two apple trees that she planted the year her first grandchild was born. She knows every centimetre of this soil.
She also knows the colony's lease with the city expires in 2028, and that the site has been flagged in Hamburg's housing development plan as a potential location for 400 new apartments.
"They talk about green cities and biodiversity," she says, pulling a weed from the bean row without looking up. "And then they want to pour concrete over the greenest thing we have."
The scale of the pressure
Hamburg has roughly 36,000 allotment plots organised into more than 300 Kleingartenvereine, occupying an estimated 1,800 hectares of land. It is one of the largest concentrations of allotment gardens in any European city. For decades, these colonies existed in a comfortable obscurity—too modest to attract developer interest, too dispersed to appear on any strategic planning map.
That changed as Hamburg's housing crisis deepened. The city's population has grown by more than 100,000 since 2010, and the current senate has committed to building 10,000 new housing units per year. Available land in the inner city is scarce, and allotment colonies—large, flat, well-connected parcels with existing infrastructure—present an obvious temptation.
Since 2018, twelve allotment colonies in Hamburg have been partially or fully dissolved to make way for housing development, displacing around 900 plot holders. A further 23 colonies are in areas designated for potential future development, meaning their long-term survival is uncertain.
The ecological argument
Allotment gardens are not just social amenities. Ecologically, they function as a dispersed network of green corridors within the urban fabric. Research from the University of Hamburg's Institute for Soil Science, published in 2023, found that allotment soils in the city store significantly more carbon per hectare than typical urban park soils, owing to decades of organic composting and minimal disturbance.
"An allotment colony is not a manicured park. It is a patchwork of micro-habitats—compost heaps, fruit trees, hedgerows, ponds, unmown margins. That heterogeneity is exactly what urban biodiversity needs, and it cannot be replicated by planting a few trees around a new apartment block." — Prof. Dr. Brigitte Öhler, urban ecology, University of Hamburg
Studies of insect populations in Hamburg's allotment colonies have recorded species counts 30 to 40 percent higher than in adjacent conventional green spaces. Hedgehog populations, which have declined sharply across the city, remain stable in areas with intact allotment networks. The colonies also provide cooling effects: thermal imaging studies conducted during the 2023 heatwave showed surface temperatures in allotment areas running 4 to 6 degrees Celsius below surrounding built-up streets.
What gardeners want
The Landesbund der Gartenfreunde, Hamburg's allotment federation, is not opposed to all development. Its position, stated in a 2024 policy paper, is that colonies should be protected where they serve demonstrable ecological and social functions, and that any displacement should require full compensation—meaning a replacement plot of equivalent size and quality, not merely a cash payment.
In practice, replacement plots are difficult to find. New allotment land must be flat, accessible, and have water supply. Most available parcels are on the city's periphery, far from the communities the displaced gardeners belong to. Several gardeners from dissolved colonies told us they had been offered replacement plots in Bergedorf or Harburg—a 45-minute commute from their original sites in Eimsbüttel or Altona. Many declined and gave up gardening altogether.
A possible middle ground
Some planners argue that the opposition between housing and allotments is a false binary. The Hamburger Kleingarten-Strategie, a discussion paper circulated by the Behörde für Umwelt in late 2024, proposed a hybrid model: partial development of large colonies, preserving 60 to 70 percent of the green space while building housing on the remainder, with allotment functions integrated into the landscape design of the new developments.
The idea has supporters in the architecture community. A student project at HafenCity University demonstrated how terraced housing could be integrated into an allotment colony in Barmbek without eliminating the garden plots, using rooftop and vertical growing spaces to compensate for the reduced ground area. It was elegant on paper. Whether it would satisfy either developers or gardeners in practice remains untested.
What happens next
At Bornkampsweg, the gardeners have formed a working group to negotiate with the city before their lease expires. They have commissioned an ecological survey, hired a lawyer, and started a petition that has gathered over 4,000 signatures from residents of the surrounding neighbourhood. Their argument is that the colony's cooling, drainage and biodiversity functions make it critical infrastructure in a warming city—not a luxury to be traded for apartments.
Helga Niemann finishes with the beans and moves to her strawberry bed. She is not optimistic about the negotiation. But she is not leaving either. "I've been here 27 years," she says. "The soil is good because I made it good. You can't build that in a season, and you can't replace it with a rooftop planter."