As Indian cities grow congested, the only space left for gardens is up – on rooftops

Mumbai resident Medha Shringarpure is a dental surgeon and amateur gardener. She started growing herbs on the window sill of her flat in Mazgaon in 2012. As her passion for gardening grew, along with the number of plants on her sill, she realised she needed a bigger garden. Given the space crunch often witnessed in the apartment complexes of Mumbai, her only option was to move up – to the rooftop of her building.

Today, the rooftop garden in her five-storeyed apartment is thriving: she grows figs, grapes, papayas, pineapples, pomegranates, seasonal vegetables such as okra and aubergine, sweet potatoes and a variety of leafy greens. The daily harvest is shared with the building’s residents. There is also a small butterfly patch for children and a variety of seasonal flowers blossom on creepers and shrubs.

Shringarpure is one among many who are successfully growing rooftop gardens. As urbanisation replaces bungalows with multi-storeyed high-rises, the space for gardens has been taken over by car parks. The plants that do grow in some of the abbreviated green spaces are largely etiolated. This is due to a lack of sunshine and fresh air as these plants often stand in the shadows of tall neighbouring buildings. It is only natural then for open rooftops in cities where summer temperatures do not cross a scorching 40 degrees to serve as healthy, alternative – if somewhat challenging – spaces to grow a garden.

Rooftop gardening started becoming fashionable in crowded urbanscapes such as New York more than a decade ago, as an expression in sustainability. While different cities need to adapt their gardening efforts according to their weather, this trend caught on globally, prompted in part by the fear of pesticides in commercially-grown produce. Some of the obvious advantages of having such gardens in India include the cooling of the rooftop and the house below, encouraging practices such as composting and rainwater harvesting, and of course the luxury of enjoying a green space in congested cities.

Spread in India

One of the Indian cities where the rooftop gardening movement is thriving is Bengaluru. The largely moderate temperatures allow such gardens to grow all year long. There are also regular workshops conducted in the city extolling its benefits.

Rooftop gardens in the National Capital Region are also growing in number. But these gardens do not flourish during the summers. Even with shaded awnings, the temperatures are too high in the months of May and June to allow a garden to thrive. This is further exacerbated by the problem of water shortage. Any available water in the overhead tanks is often too hot to use. One of the few plants that do grow well in large cement tubs, despite the heat, are water lilies. Chrysanthemum cuttings are planted in the monsoon, and the rooftops in winter are bright with garden mums and vegetables such as cherry tomatoes and salad greens, which require minimal effort to grow.

The spread of rooftop gardens in both Bengaluru and the National Capital Region is mostly restricted to private homes. One of the challenges with such gardens in housing societies is that unlike private homes, the rooftop of an apartment building is a common space, and it is not always easy to get everyone on board. Residents on the floor immediately below the roof are often worried about seepage, a commonly experienced problem. Getting the rooftop professionally waterproofed is therefore a must.

In Mumbai the rooftops sometimes have a mosaic of broken china tiles which leaves them well protected for the most part against seepage. In areas in the National Capital Region, the roofing is usually mud phuska, a type of insulating medium, with brick tiles. Here it is essential to use a good waterproofing agent as the final pointing agent for the tile layer. For rooftop lawns, a bottom layer of sturdy tarpaulin is recommended. Drainage of planters is very important and placing the planters on brick steps is also a good idea.

While growing leafy salad greens and seasonal potted flowers on the rooftop or terrace garden is simple enough, growing trees requires a lot more care, especially with the soil used. The soil must be very lightweight yet nutritious and not get water-logged. Hence a porous addition to improve drainage is essential.

Shringarpure has planted perennial fruit trees in hardy plastic drums (100 litre capacity) and the largest available grow bags. The trees on her rooftop(4500 sq feet approx) include sapota, guava, custard apple, Barbados cherry, ramphal (Bullock’s Heart), orange, sweet lime, star fruit, soursop, Indian gooseberry (dwarf amla), bananas, jamrul, purple jamun, dragon fruit, mango, lychee, ber (Indian jujube), rambutan, cashew and passion fruit. “Fruit trees like moringa, breadfruit and coconut palm are doing well too,” Shringarpure said.

Seasonal vegetables are planted on beds which are three feet by four feet with a depth of three feet, raised at a four-brick height. These beds are made of wooden planks lined with plastic roofing sheets. The vegetables include beans, sponge gourd, ridge gourds, snake gourd, bitter gourd and bottle gourd. Gourds can also be grown in lightweight planters such as apple crates (one feet by one feet and depth of two feet), as can curry leaves.

“Sweet potatoes, turmeric and ginger are grown in separate grow bags which are deep enough to cater for tubers,” Shringarpure said. “The greens include Malabar spinach, Brazilian spinach, Thai water spinach, amaranthus and roselle, among others. Aromatic herbs such as sweet basil, tulsi, mint, Indian borage, mustard, sesame and fennel are interspersed with vegetables in the bed, which helps in pollination [and act as] pest detractors.” Flowers such as bougainvillea, jasmine, gardenias, clematis, Rangoon creeper, hibiscus, rose, allamanda, oleander and plumerias are grown in planters. Her butterfly garden has clitoria, parijaat, adeniums, lantanas, vincas and honey suckle.

Since the soil must be lightweight so as not to overload rooftops, the potting mixture must be frequently enriched with rich, but not clayey, compost. This is an important aspect of such gardens, as most are organic, and Shringarpure makes her own compost. She collects the wet kitchen waste – usually vegetable and fruit peels, tea and coffee grounds and egg shells – from her entire building. These are layered in a big plastic drum in which she has bored holes all around for aeration. The wet waste is alternated with dry waste (dried leaves from the terrace garden, coco peat or a handful of red soil).

This container is raised on bricks and a vessel is kept under to catch the fluid that leaches as the waste decomposes. After about 20 days the drum is given a shake and the accumulated fluid is diluted with water and used as manure for plants. It takes about 45-50 days for the waste to decompose, after which it is transferred to heavy plastic sacks. It is left for another month and then utilised as manure for the plants.

Organic gardens do struggle to control pests, though rooftop ones suffer less than the ones at ground level. Some common deterrents include using chilly and garlic decoctions, neem oil infused with common detergent and marigold petals.

Shringarpure, who started gardening in part to cope with the loss of a loved one, describes her garden as “an expression of earth’s poetry”. “It has woken me to the wonders of creation,” she said, “all that dies like a fragile butterfly is reborn and death is only the beginning of a new dawn.”