DATE: Tuesday April 3, 2007
TIME: 7:30 p.m.
SPEAKER: Glen Patterson
TOPIC: [My] Roof Gardening
Glen Patterson spent his working life in the forestry industry and has long been a member of the Dendrology* Society. Collaborating with architects and engineers, he transferred his family garden to a new deck, high above Coal Harbour in downtown Vancouver. (* scientific study of trees).
It took 30 tonnes of earth, truckloads of cement, dozens of trees and shrubs, 250 metal hooks for wind-proofing, huge cranes and plenty of vision, but Glen Patterson created a high and mightily attractive garden. Three storeys high, in fact. "I never actually needed the hooks because the trees are so well pruned, the wind just flows through them," says the retired professional forester, who will share the story of his 200-square-metre Eden on top of the world with the Club at the April meeting.
Patterson, 85, came up with the idea of creating a rooftop garden after deciding a decade ago to downsize from a house to a condo. When he saw plans for a condominium and adjacent townhouse project on Vancouver's waterfront, he got in on the ground floor, so to speak, by buying a third-floor condo in the 28-storey building before it was built. He then negotiated to take over the adjacent townhouse rooftop, also under construction. After that came two years of negotiation, research and planning with engineers and architects and a Herculean effort by his Japanese gardener -- not to mention about $60,000 in materials and $40,000 in plants. The resulting garden has been the subject of magazine articles and is even featured in an American book called Green Roofs. Patterson chuckles guiltily when he recalls how the project manager for the development probably had no idea what a massive project was being envisioned. "I consulted an engineering friend and we decided to spread an extra two-inch thickness of concrete slab with three pounds per square foot of reinforcing steel inside it. I wanted a three-foot-deep pond, so we had to go down into the attic of the townhouse and that involved a tremendous amount of engineering too. Water weighs about 10 pounds per gallon and I have 1,500 gallons, so that's 7 1/2 tonnes."
Water-tight drainage was another challenge, so the roof was given a slight slope and Patterson installed five layers of rubber, gravel, filtration and insulation, with thin layers of cement between each. When the project manager expressed concerns, Patterson doubled it to 10. He also spent significant time researching soil, which is now a foot thick. "I wanted to have the best soil mix I could find, with good-quality compost and humus that plants love. But I quickly found out all big roof gardens made in the 1960s died because of the wrong soil mix. The organics quickly deteriorate on a roof garden." After talking to experts around North America and experimenting in his half-hectare home garden on the North Shore -- prior to moving into his new condo -- he finally settled on a combination of coconut fibre and black pumice for permeability. He also found a way to duplicate the rock features in his North Shore Garden, using cement to make imitation rock. "I had some expert artistic people who blew up cement through big rubber pipes into a steel mesh, then shaped it before it completely dried. "So I now have lovely rocks, including steps and three little waterfalls."
The roof is built to hold 250 tonnes and he has less than half that, including water. One of the biggest plants is a 100-year-old Japanese maple weighing about 3,000 pounds. "Two years before the move, my wonderful Japanese gardener of 30 years, Jim Nakano, chopped the roots off at a three-foot diameter and1 1/2-foot depth. He dug a foot-wide trench around it and filled it with sawdust in my old garden, and we left it like that for two years, to adjust. I wouldn't have believed it, but it was fine." After two years of planning and building the garden, Patterson finally moved his most valuable and treasured plants in five years ago, at age 80. They came over the Lions Gate Bridge on three flatbed trailers and were lifted by crane at dawn the next day. Because they're mostly shade-loving woodland plants -- rhodos, companion plants, perennials and a few succulents -- the filtered light between nearby apartment buildings is ideal.
While he doesn't own the adjoining rooftop, which is common property, Patterson notes he has exclusive occupancy that transfers with ownership, adding the $30-a- square-foot cost of building the garden is a small portion of the value of a million-dollar condo. "People who are surprised at the expense are usually driving around in a Mercedes Benz. A car depreciates, but this has increased the value of my apartment tremendously -- and is totally enjoyable, by me and the people who live above me," says Patterson, who developed a love of gardening with his late wife. "This is a sustainable garden," he says. "There's no mowing, no brush to cut, or hedges to trim. There are no raccoons, no sea otters, no deer. Watering is automatic. The only thing that has to be done is keep the trees pruned and once a year, we do a very systematic weeding." Even the metre-long fish in his koi pond have adapted to the move. "They're breeding now, so I'm giving some away to friends."
~ excerpted from an article written by Grania Litvin www.mcall.com