Step by Step Guide to Creating Your Rooftop Garden
Last week, we talked about the remarkable benefits of planting a roof garden on your property and the different types of roof gardens. Today, we’re going to learn the step by step process of planting such gardens, including the right plants to make the most of the space on your roof. Please read on.
1. Evaluate the Loading Capacity of Your Roof
This is a very important step to consider for an efficient rooftop garden. Different roof structures have different loading capacities - the amount of weight a roof can comfortably support. You need to evaluate how much weight your roof can handle, including the vegetation, plant containers, weather loads (such as snow), equipment, and people who’ll be accessing the roof. You may have to consult a structural engineer to advise you on how much the roof can handle and some of the preliminary designs you can adopt.
2. Check for the Relevant Building Codes
Before you begin the construction, check with the relevant authorities in your area whether rooftop gardens are allowed and whether your roof (and property) meets all the requirements. Also, if you’re a tenant in a property, seek permission from your landlord before you begin the construction.
3. Plan for Sun and Wind Exposure
Your plants will need about 6 to 8 hours of sunlight a day. Ensure to monitor the sun exposure for 1 to 2 weeks to have a clear picture of how the exposure changes throughout the day. Also, rooftops usually experience stronger winds than the ground levels, especially for several stories high buildings. You need to monitor wind exposure to determine how it will affect the vegetation; too much wind can damage or kill plants. If the wind is too much, consider structural windbreakers such as trellises or means to enhance frequent watering - wind can dry out the soil. Ensure to also install fall protection such as wind resistant demarcation for your safety.
4. Look for Heat and Drought-Tolerant Plants
There’s a high potential the sun and wind will be intense on the rooftop, which makes stronger plants a better choice for the garden. This includes plants like magnolias, honeysuckles, and ornamental grasses. Avoid large plants (and large-leaf plants) as they’ll weigh down your roof and can be challenging to place in containers or protect with windbreakers. Give priority to plants native to your area - they can adapt to the garden more easily than non-native plants. Regular watering will still be essential.
5. Building the Garden
This is where the actual construction takes place. You need to start by laying water- and root-proof membrane like a heavy-duty pond liner to cover the roof and keep the water and roots from reaching the roof surface. Next, cut into the containment frame to allow water to run into the gutter. You’ll then need to add a substrate layer, usually about 7 to 20 centimetres thick depending on the plants you intend to grow. To avoid undesired vegetation growth, use a substrate mixture of 70% and 30% organic and inorganic material, respectively. The final layer includes what makes the garden green. You can decide to have plant cuttings, plug plants, seed mixture, or pre-vegetated green roof blankets.
And just like that, you’ll have created an efficient roof garden!