A green roof generally means carpeting of plants on a roof, which improves the energy performance of buildings, and reduces storm water runoff. Though many urban dwellers have flowerpots or container gardens on their roofs, these aren’t providing the energy savings that green roofs do.
If someone set out to create a vegetable garden that would provide some of those benefits. While his garden far from carpets his roof, it does sit right against the roof membrane, helping to insulate his house, while providing fresh food for his family.
If you’d like to start a green roof garden of your own, here are some things that you might want to take into consideration:
Safety First and foremost, you want your garden to be safe. This isn’t just about protecting those on the roof from falling off. Since roofs are generally windy places, you’ll also want to protect passer-bys from falling tools. So install fencing and securely tie down all equipment. Consult your local department of buildings for any necessary permits and regulations about fence height.
Weight Wet soil is heavy. So too is a foot of wet snow on top of that soil. So you’ll want to figure out the sustainable weight load of your roof (consult a structural engineer), as too much load in the wrong places can cause structural damage. In most cases, you’ll need to use a planting medium instead of soil.
For the wood roof, a mix of 15% state permatil, 15% vermiculite, 25% compost, and 45% state is suggested. Since the nutrients have been consumed, the compost gets renewed at the start of every season, but otherwise, he estimates he will not need to replace this. When it snows, he makes sure to push the snow off the beds and hasn’t had a problem with weight load yet.
Containers You’ll need a container that is lightweight but allows drainage. For maximum energy benefits, it should sit flat against the roof. Now a day’s many use a modular planting system designed for green roofs made by Green Grid. So that the plant roots don’t burrow into his roof membrane, he lines the recycled-plastic trays with a fabric weed block. He’s also seen roof gardens created in wading pools, feed sacks, and even recycled tires.
Watering In the hottest months, you’ll need to be watering daily. Jeff solved the problem by running a garden hose up the side of his building and attaching it to drip lines and a timer system. This allows him to go away for several days at a time without worrying about his plants dying.
Plants Selection of plants is very important for green roof and few considerations are given here before selecting the plant varieties:
- Space and spread of plant foliage
- Depth of the soil: If it is lawn- 6-8 inches, if shrubs- 12-24 inches,& if tree- 36-120inches
- Plants with vigorous root should be avoided instead shallow tooted plats are preferred.
- Plants capable of withstand windy condition should be selected.
- The shape, colour, and texture of foliage should be complimentary to design features and should not clutter e.g. big plants create clutter in small spaces and tend to dwarf nearby small plants. Foliage plants are best suited to green roof.
- Plants are alive and growing element of landscaping, so growth rate, full-grown size of the plant has to be taken into consideration.
- If roof is not getting sufficient light shade-loving plants are suggested.
Plants for green roof:
- Foliage Plants: Cordyline terminalis, Begonia acutifolia, Pileas etc.
- Climbers: Hedra helix, Philodendron scandens, Ficus pumila etc.
- Ferns: Nephrolepsis exalta, Clorodesmis sp.etc
- Ground covers: Gynura aurantiaca, Sansvieria trifasciata, Ficus elastic, Helxine soleirolii, Monstera acuminate, Setcreasea pupurea
- Lawn: Cynodon dactylon(Durva), Digitaria sp.(Crab grass), Nasella sp.(Mexican Feathry grass) etc.
- Hedges: Dodonaea pupurea, Clerodendron splendens, Lantana camera, Acalypha sp.etc.
- Trailers: Chlorophytum comosum, Zebrina