The Secret of Buenos Aires' Green Roofs: How Rooftops in This Medellín Neighborhood Are Transforming the City

Buenos Aires Neighborhood and Its Unexpected Green Lung

Climbing the slopes of Cerro Pan de Azúcar, where steep streets turn into stairways and the noise of downtown becomes a distant echo, there is a neighborhood few tourists know: Buenos Aires. Not the one of tango or the Queen of the River Plate, but a working-class sector of Medellín that for a decade has been cultivating a well-kept secret on its rooftops. While the city talks about botanical gardens and linear parks, the residents of Buenos Aires have turned their rooftops into living laboratories. As of July 2026, they already have over 40 functional green roofs between Carrera 18 and the Los Balsos hill, a silent record that is changing the neighborhood's temperature and the way the city is understood.

If you arrive walking from the Buenos Aires metro station, the first thing you notice is the contrast: below, the heavy traffic of Avenida 33; above, a microclimate that is several degrees cooler. The rooftops are not decorations. They are gardens, community gardens, and meeting spaces that filter smog, retain rainwater, and cool the block and Eternit tile houses. In a neighborhood where 70% of homes are self-built and the sun beats down mercilessly, these green roofs are not a luxury: they are climate survival.

History of the Rooftops: From Clandestine Gardens to Community Projects

The story begins in 2015, when a group of women from the "Semillas de Esperanza" community kitchen decided to plant cilantro and lettuce on a 30-square-meter terrace. They didn't ask for permission. They just wanted to lower the cost of food. Those first gardens were rudimentary: recycled plastic baskets, soil brought in buckets, and seeds bought at the Plaza de la 45. But they worked. In three months, the cilantro grew so thick that neighbors started asking how to replicate it.

By 2018, the Mayor's Office of Medellín, through the Ministry of the Environment, launched the "Techos Vivos" program in Buenos Aires, offering technical assistance and materials in exchange for residents maintaining the crops. What started as a pilot of 12 houses expanded quickly. Today, the neighborhood's Community Action Board keeps a record of 46 active green roofs, including two in educational institutions and one at the San Martín de Porres chapel. The curious fact: most of the caretakers are older adults who found in vertical gardening a therapy against loneliness.

What sets Buenos Aires apart from similar experiments in El Poblado or Laureles is the human scale. There are no big investments or star architects. There are neighbors who learned to waterproof with recycled tar, to plant in cut PET bottles, and to water with treated gray water. It is sustainability from the bottom up, without green marketing filters.

Tour: The 5 Must-See Rooftops and How to Visit Them (With Neighbor Permission)

Visiting these rooftops is not like going to a tourist viewpoint. There are no ticket booths or fixed hours. The golden rule is to ask permission, knock on the door, and if they offer you a tinto (black coffee), accept it. Most owners are proud to show their work, but distrust of outsiders is real. Bring something to talk about: ask them about the weather, the harvest, the neighborhood. Never enter without greeting.

1. Terrace of the Buenos Aires Cultural Center

Address: Calle 44 # 18-45, half a block from the metro station. It is the most accessible for visitors. It has 200 square meters of vertical garden with native plants (ferns, bromeliads, and marigolds) and a small herb garden. Entry is free, but it is recommended to coordinate with the administration (ask at reception for Señora Marta). Open Monday to Friday, 8am to 5pm. Saturdays there is a composting workshop at 10am.

2. Restrepo Family Rooftop (Calle 43A # 19-32)

Don Luis Restrepo, a 68-year-old former bus driver, transformed his 25 m² terrace into a paradise of tomatoes, chili peppers, and lettuce. It is one of the most photogenic: the plants climb up the wrought iron railings and there is a wooden bench where he sits to read the newspaper. Don Luis receives visitors on Saturdays from 9am to 12pm, but only if you ring the bell beforehand and tell him you come on behalf of Malokal. He does not accept money, but appreciates if you bring him seeds of a variety he doesn't have.

3. Community Garden "La Loma Verde" (Carrera 20 # 44-08, corner)

It is the most ambitious project in the neighborhood: a 150 m² rooftop shared among 8 families. They have a homemade drip irrigation system with bottles, a recycled plastic greenhouse, and even a stingless bee hive. Workdays are organized on Sundays from 7am to 11am, where anyone can help in exchange for taking home vegetables. It is the best place to learn vertical gardening techniques without paying for a course.

4. Terrace of Buenos Aires School (Calle 42 # 18-10)

Students from grades 9 to 11 maintain an 80 m² green roof with medicinal plants (aloe vera, mint, lemon balm) and a nursery of native trees. It can be visited with prior authorization from the principal's office, by calling the school switchboard. On Wednesdays at 2pm there are guided tours by the students themselves. It is a moving experience to see the kids explain the water cycle with the passion of those who have planted with their own hands.

5. Rooftop of San Martín de Porres Chapel (Calle 45 # 19-50)

Father Carlos, a 55-year-old priest with a beard and hat, convinced the diocese to turn the chapel's roof into a prayer garden. There are succulents, cacti, and a small outdoor altar. The 8am Sunday masses end with a blessing of the plants. You can go up after the service, but not during the Eucharist. Father Carlos gives permission if you tell him you are going to meditate.

Climate Impact: How Green Roofs Cool the Hillside and Filter Smog

In Medellín, temperatures have risen an average of 1.5°C over the last 20 years, according to IDEA data. In neighborhoods like Buenos Aires, built on hillsides with little original vegetation, the heat island effect is brutal: concrete streets and asbestos tile roofs can reach 50°C at midday. Green roofs change that. A 2023 study by the National University, Medellín campus, measured that a rooftop with 15 cm of substrate and native plants reduces the interior temperature of the home by 3 to 6°C during peak hours, without the need for air conditioning.

Additionally, the plants filter fine particulate matter (PM2.5) generated by the vehicle fleet on Avenida 33. One hectare of green roof can trap up to 10 kilos of dust per year. In Buenos Aires, where the 46 rooftops total approximately 0.8 hectares, it is estimated they remove nearly 8 kilos of pollutants each year. It is not a magic solution, but in a neighborhood where many children have asthma, every gram counts.

Another less visible benefit: rainwater retention. During the April and October storms, green roofs absorb between 50% and 80% of precipitation, preventing water from running downhill and saturating the sewers. In 2022, when a sudden flood inundated the lower part of Avenida 33, the houses with green roofs in Buenos Aires reported no leaks or structural damage.

Practical Guide: How to Join a Vertical Gardening Workshop or Create Your Own Rooftop

If you are left wanting your own green roof, Buenos Aires is the ideal place to learn. The workshop offerings are informal but effective:

• Free workshops by the Community Action Board: Held on the first Saturday of each month at the Casa de la Cultura (Calle 44 # 18-45). They cover everything from basic waterproofing to designing irrigation systems with recycled materials. No prior registration needed, just arrive at 9am.
• Paid courses by the Medellín Botanical Garden (Buenos Aires extension): Once a quarter, the Botanical Garden sends an instructor to the neighborhood for an intensive 2-day workshop (Saturday and Sunday, 8am to 4pm). It costs $80,000 COP and includes substrate, seeds, and a printed guide. They are announced on the Board's bulletin board.
• Informal learning with neighbors: If you earn the trust of Don Luis or the ladies of "La Loma Verde," they will teach you for free in exchange for help on weekends. Bring gardening gloves and a willingness to get your hands dirty.

To create your own rooftop, here are the basic steps recommended by locals:

1. Check the structure: Make sure your roof can support at least 100 kg/m² of wet weight. In Buenos Aires, block and concrete slab houses hold up well; Eternit tile roofs require reinforcement. Consult an engineer if you have doubts.
2. Waterproof: Use an asphalt membrane or polyethylene geomembrane. At neighborhood hardware stores (like Ferretería Buenos Aires on Calle 44) they sell rolls from $50,000 COP.
3. Add a drainage layer: Coarse gravel or pumice stone 5-10 cm thick. Prevents water from stagnating and rotting roots.
4. Add the substrate: A mix of black soil, compost, and rice husk (ratio 2:1:1). At the Plaza de la 45 they sell 40 kg bags for $15,000 COP.
5. Choose native plants: Ferns, bromeliads, marigolds, mint, rosemary, and thyme. Avoid invasive species like cat's claw. Succulents also work well in sunny areas.
6. Install drip irrigation: With perforated PET bottles and a 1/4-inch hose. Don Luis's system costs less than $30,000 COP in materials.

Local Tips

• Ideal visiting time: Between 7am and 10am, when the sun is not too strong and neighbors are watering. After noon, many rooftops close due to the heat.
• Dress practically: Wear closed-toe shoes with non-slip soles and clothes you can get dirty. The rooftops have soil, water, and sometimes organic fertilizer.
• Bring cash: In Buenos Aires, there are no card machines in homes. If you want to buy vegetables or seeds, bring bills of $5,000, $10,000, and $20,000 COP.
• Language: Most neighbors only speak Spanish. If you are a foreigner, learn basic phrases like "¿Puedo subir a la azotea?" (Can I go up to the rooftop?) or "¿Me enseña cómo siembra?" (Can you show me how you plant?).