Ruling the roof; Four storeys up, plants chosen to withstand the elements flourish in a rooftop garden full of charm.
IN HER south-facing Primrose Hill garden, Catherine Horwood grows mimosa and olive, clematis and roses, bamboo and grasses, oldfashioned pinks and drought-loving succulents. She harvests blackcurrants by the bowlful, picks lemons straight from the stem and can choose from two varieties of apple - grafted on to the same tree. Her garden would be a peach of a place if it were at ground level, like most people's, but what makes it more remarkable is that Horwood's plant-packed plot is a breezy four storeys high - and her borrowed landscape, on a clear day, is the Eye, the Gherkin and Canary Wharf.
"I used to have a traditional long, thin garden in north London," says Horwood, an honorary research fellow at Royal Holloway, University of London.
"When I moved here, three years ago, I thought I wouldn't be able to grow my favourite herbaceous plants, but I have quite a few that are happy in pots, such as hostas, hardy geraniums and crocosmia. I love clematis and I've found that they are tougher than people give them credit for. I can't bear not to have roses and have discovered that they can tolerate wind; Roserie de L'Hay, for example, is gorgeous and, like all the rugosas, is as tough as old boots."
Horwood also used to have a seaside garden, which gave her experience in knowing what would thrive on a rooftop. "The conditions are similar to the coast, because it can be extremely windy, which is also drying, and we face due south, so the sun beats down. Hence I focus on Mediterranean plants. I tend to grow either plants that crouch low, out of the wind, so that even the tulips I choose are short, or tall plants that sway and swish with the wind, such as bamboos and grasses."
Seaside gardeners have to put up windbreaks, and so did Horwood. "I wired a green-mesh windbreak to the boundary railings, and then attached rush screening in front of it. You must not stop the wind completely, or it whips over the top, which is even worse." She uses her container plants to manipulate the view and lend a little privacy. An Italianate cypress tree is strategically placed to disguise the block's TV aerial and standard forms of roses and shrubs such as Pittosporum tobira add height higher up and take up less space lower down. "Even the blackcurrant and my fruit trees - plum and apple - are columnar, like maypoles, with the fruit growing from short side shoots."
Succulents are perfect because they are impervious to wind and need no watering at all, she says, but she brings them indoors for winter. As the roof garden runs alongside her glass-fronted living room, it's an easy matter to range them along the two steps just the other side of the sliding glass windows, which, facing south, keeps them cosy.
The roof garden has all the trappings of a garden on the ground. The floor is paving slabs, softened with pillows of bright green mind-your-own-business and self-seeded alpine pinks. There is a little garden shed tucked into a corner, which resembles a sentry box for a rather small soldier. The star feature is a handsome pergola painted sea-green under which the dining table and chairs are positioned. Its beams are covered with a sheet of split bamboo and are charmingly strung with small pots and baskets of succulents, just as tropical orchids would be.
Two trellised walls at either end have atmospheric circular moon windows cut into them that make, says Horwood, wonderful through views; she bought the panels for a snip at B&Q. The pergola and the various benches, pushed against the walls with pots slotted behind them so that the visitor is surrounded with aromatic rosemary and lavender, turn the roof garden, says Horwood, into a great summer living space for family and friends. There was a full-size patio heater but alarmingly, it blew over, so Horwood brought in safer bets: a pair of infrared wall heaters attached unobtrusively to the struts of the pergola, along with spotlights. "Lighting is terribly important when you can see out of your living area straight into the garden," she says.
Horwood is delighted that she can grow bulbs without fear of squirrels digging them up, but other familiar pests manage to wreak havoc.
Slugs come in as eggs, in the pots, and so do vine weevil. "I originally hung up lots of my containers because vine weevil can't fly, but I soon realised that they simply walk out of a pot and up the ropes, along the pergola strut, then down the nearest rope to the next pot."
The top of the lift shaft, which was an eyesore until Horwood had it decked over, has become a deep display bench for special plants such as alpines, which are cosseted in a tufalookalike trough that is made of much lighter plastic. "This is where I grow plants I had in my last garden, in miniature; it's the perfect level for seeing things close-to." It's also the perfect level for sniffing fragrant plants, like the oldfashioned pinks Horwood keeps in check with a surrounding circlet of bamboo hoops. Later in summer, their perfume will be replaced by lilies she has selected for their sublime fragrance: Casablanca and regale. Seeds don't come in on the wind, but they appear to go out on the wind, says Horwood, and are responsible for a new landscape greening four storeys down.
The euphorbia characias she grows seeded itself in the cracks of the paving at ground level, and created a small bank of euphorbias at the back entrance to her block of flats. Nobody is complaining.