HOME INTERIORS Raising the roof

My WORK has been high in the sky this week, planting a rooftop garden in London. Like much of the country, it’s been bitterly cold and very windy.

The tops of roofs provide little shelter making it colder and more exposed than at street level – and it’s important to remember this fact when choosing plants for such situations.

At street level or in courtyards in towns and cities, the heat and shelter provided by buildings creates microclimates where even slightly tender plants can survive.

But higher up, whether it is balcony gardening or on the rooftop, plants need to be tough enough to brave the elements, and not get blown to bits by the wind or freeze in the chill.

Summer also bri n g s challenges in these exposed areas – because there is typically no shelter from sunshine, plants will dry out very quickly.

Also, many terraces or balconies may be situated beneath another balcony so you can’t rely on rainfall to keep them hydrated.

The plants that survive best in elevated situations are those that also thrive by the sea or are drought resistant. Their leaves are adapted to withstand the desiccating effects of salt-laden winds and retain moisture. For example, the leaves of escallonia are slightly sticky which repels salt, elaeagnus has leathery leaves with a silvery underside and hebes have double thickness skins.

Silvery looking shrubs such as lavender, santolina, stachys, corokia and olearias have fine layers of hair that protect leaves from drying out.

Dwarf pines with their needle-like leaves, grasses and sedges are also suitable, as are plants with tough leaves such as phormiums and cordylines.

Of course, you’ll also want colour – again think of resilient plants that grow at the seaside such as pinks, thrift, osteospermum, valerian and erigeron.

The type of container you use is also important. Small terracotta pots will dry out very quickly but If there is no space around your home for a garden, create one on a balcony or the roof there are plenty of other options that are non-porous such as metal, plastic, fibreglass and resin.

Ensure they are suitable for outdoors and won’t crack or deteriorate through exposure to ultraviolet light. If you are using metal pots make sure they are suitable for wet environments. Mild steel will rust unless it has been powder coated, galvanised or painted in a water-resistant coating.

With metal containers I often try and ensure some type of insulation by introducing a coating of foam or polystyrene sheeting between the compost and the outer metal layer. Galvanised steel dustbins are an inexpensive option once they have some drainage holes drilled through the bottom.

If you are using wooden containers they need to be treated with a preservative. And wherever you are setting them, allow for good airflow all around so they won’t rot.

Old wine or vegetable crates can double up as plant containers – line them with hessian or moss to contain the compost. Mediterranean herbs such as rosemary, thyme and mint would look great planted like this and they are also plants that have adapted to manage their native drought conditions.

So specimen choice and container choice are key.

However, as with all container gardening, you’re responsible for their feeding and watering requirements as they are not able to obtain this for themselves from the earth.

Simple irrigation systems are your best bet for plants surviving in these situations – it need not be a huge investment but it is definitely worth it to keep your elevated greenery green and you won’t need to get up there with a watering can quite so often.