Making the most of all the growing space available in cities is key to a sustainable urban existence. Rooftop gardens are proliferating as people seek to grow their own food and flowers and green urban spaces.
Although urban rooftop gardens can be a wonderful idea, there are certain considerations and elements to be taken into account to ensure that such a project is a success. As a garden designer I have worked on the development of a range of rooftop gardens around the world. Here are my tips for designing a garden of this type.
Determine the bearing capacity of the roof
Many flat roofs can be used to develop a roof garden. But it is important to realize that not all flat roofs will automatically be suitable for this purpose.
If you have a flat roof on which you want to create a garden, one of the first things to determine is how much weight that roof can support. Safety is essential. It is essential to check the structural integrity of the roof.
Ideally, you should consult a structural engineer who can tell you if the roof is currently strong enough to support the weight of people and a garden. The roof in question may need to be reinforced before it can be used.
Consider access and convenience
A rooftop garden can potentially become a refuge and a boon for people. But such a garden will need to be safely accessible for use. Think about how people will access the space, and also how easily it will be possible to import the materials that will be needed to create and maintain the garden.
One of the main challenges when it comes to rooftop gardens are the stairs that have to be taken to access them. It can be difficult to get the materials, tools, and other things you need to create and maintain the garden up and down those stairs. You may want to think about allocating space in the garden to keep these things in place (where space permits).
You can create a storage shed or a storage area for tools, for example. And you should also consider a place for composting on the roof itself, so you don’t have to haul heavy, bulky organics up the stairs. And when you can create your own compost for a rooftop garden, it can save you money and avoid having to import materials to fill pots and containers.
Water is another thing to think about carefully when creating your design. A garden that requires you to carry watering cans up stairs won’t be practical at all in the long run. So you need to build water into your plans right from the start.
Think about specific environmental characteristics
Before you even start thinking about what you’ll grow in a rooftop garden, how you’ll grow it, and what goes where, you need to analyze the site.
Rooftop gardens have a range of very specific characteristics. Often the key considerations for such a space can be the creation of windbreaks and shade. Roofs tend to be exposed and windy. They are also exposed to full sun and can heat up and dry out quickly. Careful consideration of water and irrigation, proper cultivation method and plant choices is essential. The solutions and installations you choose must be suitable for these specific environmental conditions.
Determine how you will grow, choose the growing method(s)
When choosing a growing method, you should remember that rooftop gardeners use a range of different options. As in other garden types, you can grow in containers, on the ground or in vertical systems, or in larger planters or raised beds. Often rooftop gardeners consider growing hydroponically, in water rather than soil, or even consider aquaponic systems – raising fish in addition to plants.
When considering the different options, be sure to keep weight in mind and consider how practical the option will be in your particular roof space. Only when you have taken a close look at the space and decided on a growing method (or methods) can you focus on the specific plants you are going to grow.
Designing for people as well as plants
A final basic consideration for rooftop gardens is that you should design for people’s enjoyment, as well as creating optimal environmental conditions for plants. City rooftop gardens are often not only exposed but also neglected. Create privacy by blocking sight lines to give a rooftop garden a private and tranquil feel. Rooftop gardens, however, can also offer stunning views. Thus, the enjoyment of particular views must be balanced with the desire for a more sheltered and private space.
These are just a few basic things to think about before focusing on the details when working on a roof garden design.