Roof-Top Container Gardens
Apartment-dwellers who long for a plot to tend or gardeners with a wish for a secluded retreat can add a new dimension to their living space by using their roof. Create a garden with a view, high above the city streets.
Even the smallest area of an apartment roof can become a garden with a few carefully chosen and planted containers. But before you transform yours into an urban oasis, consider a few practicalities.
The most important thing to establish is whether your roof will bear the weight: this will mean having a structural survey. You can reduce the weight of your pots by using plastic or glass-fiber containers instead of terracotta, and for drainage, crumbled polystyrene instead of broken crocks. However, a tall plant, particularly in a windy spot, may need to stand in a heavy pot to prevent it from blowing over.
Good drainage is also crucial. In high summer, containers on a sun-baked roof will need watering every day -- but a roof terrace covered in puddles will not entice you outside.
Think about access to the roof, loo. Will you be able to move pots, compost and large plants up there? Can you fit an outside tap or irrigation system, or will you need to carry full watering cans up awkward steps?
Plants in High Places
Most roof gardens will need some screening, either from the elements or from overlooking buildings. Tall, wispy bamboos and grasses offer privacy without blocking out light, while trellis panels cloaked with climbers make a more sturdy windbreak.
If you are lucky enough to have a great view, frame it with a pair of sculptural plants. But if your outlook is less appealing, create focal points within the garden by including a few dramatic specimens to draw the eye.
Even in a limited space, a few substantial shrubs, such as a large-leaved fatsia will add interest and scale.
Long strappy leaves can be shredded by strong winds, but many trees and shrubs, including cotoneasters, elaeagnus and mahonias, are more resilient and make excellent roof-garden plants.
Resist the temptation to position all your pots around the walls. More creative arrangements, such as banks of plants at different levels, will make a much more interesting display and can help to make the space seem larger than it is. Following a theme or simple color scheme can also help to create an illusion of space.
Few roof gardens are large enough to store more than a few pots of bulbs out of season, so it is important to plan carefully. A bench that doubles as storage space can accommodate the few tools the container gardener needs.
Make every plant earn its space on the roof. Choose long-flowering varieties and plants with something to offer after their flowers have faded. The pure blue blooms of Chinese plumbago (Ceratostigma) make it a brilliant choice for summer color, and its leaves glow a brilliant red in autumn. Choose as staples plants that will provide interest all the year round and use evergreens as a backdrop for showy seasonal specimens.
Do not let the height of your garden deter you from experimenting with exotic or tender species. Heat rises from buildings and will give warmth to a sheltered roof garden even in winter.