The ALTMARKTgarten rooftop greenhouse, located on top of a public building, is currently under the leadership of head grower Wolfgang Grüne. This unique space has become a center for innovation, education, and community engagement, offering a glimpse into the potential of city-based food production. The 1,100 m2 greenhouse is realized at a height of 25 meters.
Wolfgang Grüne at one of his projects
Their vision of sustainability
Originally trained as a biotechnical assistant, Wolfgang quickly realized his calling lay elsewhere. After discovering aquaponics—a system that integrates fish farming with plant cultivation—he knew he wanted to devote his career to sustainable agriculture. "Aquaponics was mind-blowing for me," Grüne recalls. "I had always been interested in gardening and fishing, but this was something new and exciting, sustainably combining fish and plants."
After earning his degrees in agricultural science and specializing in plant production and aquaculture, Grüne embarked on his journey in urban farming. His expertise now drives the Altmarktgarten project amongst others, which integrates modern technology with traditional farming principles to create a highly efficient and eco-friendly system.
Urban farming
Altmarktgarten isn't just an ordinary greenhouse—it's a model for urban farming in dense city environments. The greenhouse produces a variety of crops, including strawberries, basil, rosemary, chives, thyme, and other herbs. Visitors to the greenhouse can see these crops growing in an environment designed to make the most of every square meter of space.
Grüne is proud of the diversity of crops they are able to cultivate. "We grow lettuces hydroponically, and our herbs and strawberries are grown in substrates but not the classic hydroponic way," he explains, referencing the method of growing plants without soil, using nutrient-rich water. Hydroponics allows for higher yields in a smaller area, making it ideal for urban settings where space is at a premium.
The crops are not only grown sustainably but the entire operation is built with eco-friendly principles in mind. The greenhouse is connected to the city's waste heat network, using residual heat from local industrial processes to warm the greenhouse during colder months. Rainwater is collected in tanks and reused to water the plants, further reducing the environmental impact. "It's a highly integrated system," says Grüne. "We've designed it to minimize waste and energy use wherever we can."
The ALTMARKTgarten rooftop greenhouse at night
A learning environment
One of the key missions of Altmarktgarten is education. The greenhouse regularly hosts school groups and families, offering tours and hands-on experiences designed to teach people about sustainable food production. Wolfgang believes that inspiring the next generation to care about where their food comes from is one of the most rewarding parts of his work.
Children visiting the greenhouse are treated to an interactive and sensory-rich experience. They are invited to explore the greenhouse, smell the fresh herbs, and even plant their own lettuce to take home. "The children love it," Grüne says with a smile. "They can touch the plants, smell the herbs, and take a small plant home to grow themselves. It's amazing to see their excitement and curiosity."
This educational component is vital in a world where many young people are disconnected from the sources of their food. By giving children the opportunity to experience farming firsthand, Altmarktgarten helps foster a deeper understanding of sustainability and the importance of green spaces in urban areas.
Overcoming urban farming challenges
Operating a greenhouse on a rooftop in the middle of a city presents its own unique set of challenges. For one, moving supplies, tools, and plants up to the rooftop requires careful logistical planning. "Everything has to be transported up by elevator," Grüne notes, "which can be a bit of a challenge when you're running a farm."
Pigeons also occasionally find their way into the greenhouse, creating another obstacle. "They love the warm, protected space as much as the plants do," Wolfgang says with a laugh. Despite these issues, he is quick to emphasize that the benefits far outweigh the challenges. "It's part of the adventure," he says. "Every farm has its quirks, and we've learned to adapt."
Another hurdle is energy consumption, especially during the winter months when artificial lights are needed to supplement the limited natural sunlight. Wolfgang acknowledges that energy prices can be high, but the greenhouse's connection to Oberhausen's waste heat network helps mitigate costs. "We try to use artificial lights as efficiently as possible," he explains. "It's all about balance."
Future developments and goals
Beyond the day-to-day operations of the greenhouse, Altmarktgarten is part of a broader movement toward sustainable urban living. The project is funded by the city of Oberhausen and serves as a model for other urban farming initiatives in Germany. Plans are already in place to replicate similar rooftop greenhouses in Hamburg and Berlin, with hopes of expanding the concept to other cities in the near future.
Wolfgang sees rooftop greenhouses as a key component in creating greener, more sustainable cities. "It's not just about growing food," he says. "It's about rethinking how we use urban spaces. Greenhouses like this one can help cities become more self-sufficient and reduce their environmental impact."
Visitors who tour Altmarktgarten leave with more than just a newfound appreciation for urban farming—they gain insight into the future of food production and the role that cities can play in creating a sustainable world. Wolfgang concluded optimistically: "We're showing people what's possible. If we can grow fresh food on a rooftop in the middle of a city, we can do it anywhere."
Visit Wolfgang's YouTube channel for more information (please note it is in German mostly).
For more information:
Grüne Innovtion GmbH
https://www.wolf-aqua.de/
Email: [email protected]
Roermonderstarße 100
41379 Brüggen