Roof top gardening does more than just bring plants closer to you,
it can improve the world.
Urban residents across the world are starting to look up and turn a plentiful resources into a solution green roofs. A green roof is a roof that is also a garden from a simple container garden to a roof covered with several inches of a soil and a meadow. A garden always provides a space to relax but the limitation of space in big cities and towns has greatly limited the scope for enjoying its beauty at home. It is therefore the need of the hour to earmark some area on the roof top for raising various plants so as to bring the real magic of nature to your home with some previous planning and thoughts.
CHOICE OF PLANTS
A wide variety of plants can be used for growing on roof tops but it is necessary to choose the plants with shallow root system which will not penetrate the roof floor in the long run. At the same time, it is also advisable to grow such plants that flower at various periods of the year and are very easily maintained at roof tops. Delicate plants must be avoided for this purpose. The following plants are well suited for such types of gardening:
Foliage plants: Asparagus, coleus, croton, diffenbachia, dracena, paperomias, philodendron rubber plant, etc.
Flowering plants: Seasonal flowers like antirrhinum, aster, balsam, calendula, celosia, cosmos, daisy, dianthus, gaillardia, marigold nasturtium, pansy, phlox, verbena, zinnia, etc., and perennial flowers like carnation, chrysanthemum, dahlia, rose, tuberose, etc.
Trees: Ashoka tree, bottle brush, chrismis tree, silk cotton tree, etc.
Climbers: Antigonon, begnonia, gloriosa, ipomea and passiflora, etc.
Cactii and succulents: Agave, aloe, kalanchoe, opuntia, cehpalocereus, notocactus nyctocereus, etc.
Fruits: Gooseberry, strawberry, peach, pear, pineapple pomegranate, etc.
Vegetables: Bringal, broccoli, chillies, lettuce, tomoto, etc.
Shrubs: Acalypha, bougainvillea, camellia, and china rose, geranium, jasmine lantana, etc.
Generally a soil layer of 10 to 20 cm thickness is sufficient for planting various foliage and flowering plants. A good soil mixture for roof gardening must consist of soil, sand and well rotten FYM in 2:1: I ratio for flowering plants. But for foliage plants, a mixture containing equal part of soil and organic manure is the best.
Before potting, the container should be thoroughly washed and sterilized with 5% formalin solution. A small piece of curved pebble should be placed over the drainage hole to prevent its blocking. For proper growth and drainage, coarse sand should be placed at the bottom over which a mixture of soil and organic manure may be added to fill up the container, leaving 2.0-3.0 cm pot brim for irrigation. Planting is to be done by making a hole in the center so that any injury to young plant or its roots may be avoided. While planting, the soil around the plant is pressed to hold it firmly in the growing medium. A light watering is required immediately after planting and should be done with the help of rose cane. After that the plants are kept in the shade for about a fortnight before being placed at their actual location on the roof.
The pot should be checked once in a year during monsoon season and repotting is required if the roots of the plant are found to bound the entire pot. Repotting may also be required if any plant looks too large for its pot or the water passes through the pot too quickly. Repotting is done either in bigger pot or in the same pot with fresh garden soil and manure after light root pruning.
The secret of a successful garden mainly lies in the harmony of the surrounding. Therefore, some special features like greenhouse, lily pools, rockery etc , may be added later but these garden features must be in mini-form. For a greenhouse, use aluminum pipes for longer duration and bamboo poles for shorter duration. In such greenhouses, floor surface can be used for container plants; the walks for climbing plants and the air space for the plants in hanging basket. A rock garden should not exceed 0.5 to 1.0 m height while a lily pool must be painted with a light blue colour inside and any contrast colour outside. In order to minimize weight load on the roof, these garden features may be constructed with fibre-glass, plastic or aluminum sheets. Aluminum sheets are comparatively cheaper and can easily be moulded according to the desired shape of these features. These are then placed inside the soil on the roof surface to bring harmony to your garden.
The plants grown on roof tops require various cultural operations for effective management of the garden. Among these, pinching of 2.0 to 2.5 cm shoot tips is a regular practice to make the plants become bushy. In shrubs and fruit trees, pruning is required to check excessive growth once in a year after their flowering. Likewise, training is essential to give a definite shape to the plant while stacking is a must in climbers to keep them upright. Regular weeding of plants is very essential to keep the garden free from pests and diseases. During summer and rainy season the plants should be protected from strong wind and scorching sun as the roofs are always exposed to these conditions. The protection against such extreme conditions can be provided by putting a screen or an overhead pergola structure made up of bamboo sticks which can last 3 to 4 years. For permanent structure, one can use wrought iron or aluminum but the cost will be high.
Apart from this, watering has a direct impact on the over-all performance of the roof garden as most of the plants may die due to inadequate or over-watering. The water requirement of the plant increases during its flowering stage and the frequency will be much higher if it flowers during summer season. Cactii and succulents require less frequent watering as compared to all other plants. Keeping this in view, watering is done when the soil just starts drying but always before it is completely dried up. In order to conserve the moisture when a person is away from his house for a few days or so, it would be an excellent idea to put one end of a saturated rope piece near the plant and other end in a bucket containing water. The same can also be achieved by wrapping the pot and the plant in a polythylene sheet.
There are many advantages of roof top plantation. Green roofs help moderate temperatures, improve air quality, reduce storm-water runoff and create habitat for birds and butterflies. They also create an oasis in a concrete jungle. No doubt, rooftop gardening does more than just bring plants