The first roof plot we will be working with is located on the northeastern side of Colombo and has approximately 60 square feet with full sun throughout the day.
With this amount of exposure and tropical climate, temperatures can reach extremes. It will be important to find the best mulching and water conservation practices, and the hardiest vegetable varieties to keep this garden healthy and low maintenance.
Though the square footage is modest, at best, I find this the perfect setting to develop vertical growing structures. These obviously help to make the most use of space, but can also be resource-efficient by combining fertilizing, watering, and compost/growing medium development.
The two vertical methods I will focus on primarily are tower and wall structures. The growing towers will be constructed of easily sourced local materials including wood, bulk grain bags, shipping crates, and other recycled materials. These towers will function very similarly to the African keyhole and bag gardens in which plants are tucked in along the sides and around the structure, and food scraps and water are added to a center reservoir running the height of the tower to leach nutrient-rich compost tea to all of the roots. Additionally, the vertical planting allows for the creation of micro-climates enabling gardeners to grow a variety of vegetables, including tomatoes and more tender salad greens, in much less space than would be required of traditional horizontal garden plots.
The second, wall structures, are meant to better serve running vegetable varieties that require more space for vines and support for hanging fruits. These can also be used to grow other vegetables in even more limited growing spaces such as an apartment with no roof access but a sunny window or balcony.