Roof gardens are a great option for getting a little closer to nature if you don’t have enough outdoor space. They can create a little haven for you and for wildlife like birds and butterflies too.
Here’s how you can set up your own roof garden and pick plants that will thrive in it:
Setting up your roof garden
To begin with, you need to make sure your property can safely handle the extra weight of having a garden on top of it. A structural engineer can tell you if this is the case.
If you don’t already have access to your rooftop, you might want to install an opening rooflight, such as one of our sliding rooflights.
If you do have access to your rooftop then perhaps you might consider a walk-on glass rooflight. These are made from toughened glass so they can deal with the weight of people walking over them. Walk on rooflights can add that wow-factor to your roof garden, as well as providing additional light into the room below.
You also need to make sure you are not breaching any local building regulations. Then there are the practicalities of maintaining a roof garden. Consider if you have a good water source and sufficient drainage.
Roof gardens tend to be exposed to windy conditions, so you need containers that won’t be toppled over easily. Opt for containers that are low and wide rather than tall and thin. You may also need to fix them. To help with the wind exposure, you can use a wire mesh around your garden. You can also use windbreak plants like certain waxy cuticles or climbers.
Choosing the right containers will also help keep your plants alive and healthy. The wind and sun exposure on roofs means plants are likely to lose moisture quickly, so containers made from non-porous materials, like metal or plastic, are better than others like terracotta, which lose moisture. You can also use containers with drainage holes in their base.
Using soil and compost
Because roof garden plants have less access to nutrients, your compost needs to provide them with plenty of nourishment. To retain moisture, you can also mix materials like perlite into your compost.
Choose lightweight soil specifically for rooftop gardens.
Plants that grow well on roof gardens
Plants that naturally thrive in sunny and windy settings, like coastal or mountain areas, are your best bet.
The Rock Rose (Cistus) is a colourful aromatic evergreen plant that blossoms in hot sunny weather but can also withstand colder temperature of up to -5°C.
Other aromatic evergreens like rosemary and thyme also do well in sunny, dry and windy conditions. When it’s hot, the oil from the plants give off a lovely scent. Oregano, a Mediterranean rocky hill native, is another wonderfully fragrant choice.
Grasses and succulents
Ornamental grasses can help add a touch of drama to your roof garden. Juniper and phlomis, which are common on Mediterranean hillsides, are a good choice as are pinks and thrifts, which do well on rocky coastal landscapes.
Succulents are particularly trendy at the moment but they have always been a staple for roof gardens. Stonecrop (Sedum spp) is the most established roof garden succulent and comes in a huge variety of colours.
Although flowers require more maintenance than other plants, the colour they add makes it worth it for many gardeners. Gazanias, also called the African daisy, comes in a variety of colours from yellow to red and is sometimes two-toned. The only care they need is being watered occasionally, even though they are generally drought-proof.
Swiss trailing gereniums are popular around Europe, where their vividly coloured pink and red flowers can be seen tumbling down balconies and hanging baskets.They require little care apart from being watered and occasionally cutting off wilted flowers.
Fuschias do well in containers and can even survive in full shade which makes them a great choice for adding some vibrant colour to your roof garden.
If you prefer the look of wild flowers, Aster alpinus is a gorgeous choice with its thin purple petals and yellow centre – butterflies love this alpine flower too. Yarrow, another wild flower, is commonly used as a medicinal plant and is a great choice for rooftop gardens because it is very hardy. When in bloom, between June and November, it creates a beautiful bed of white flowers. You’ll need to buy cultivated yarrow since wild yarrow is a weed.
If you’d like to get more than beauty from your garden, there are several vegetables that will do well on rooftops. Lettuce, courgettes, spinach, kale and swiss chard are all good choices. You may also have some success with cucumber and cherry tomatoes.