How does your (rooftop) garden grow?
Special to the Daily
they call it the hobbit house: Within the European-themed Vail Village sits a home with a slanted, green-growing roof. It’s a predecessor to the Betty Ford Alpine Gardens’ Alpine Center, which sports both a rooftop garden and a green roof. The two buildings prove it’s not only possible, but also quite practical to grow plants on rooftops.
But there’s a big difference between green roofs and garden rooftops. Garden roofs provide extra outdoor living space on top of a home; it’s truly a livable area, with concrete pavers and planters, or other means of designing a garden atop a home. Green roofs, on the other hand, employ sedum and other perennials to replace shingles or metal with a vegetative material, which grows 12 to 18 inches high.
“ A green roof (requires) decreased maintenance and lowers energy costs,” says Nick Courtens, senior horticulturalist at the Betty Ford Alpine Gardens. “A garden roof caters to someone who does more gardening and wants to control what they grow.”
A truly high country garden
Homes planned with flat roofs become candidates for rooftop gardens, a place where homeowners can grow herbs, edibles and flowers in planters. However, garden roofs require proper waterproofing so it “works like a normal roof,” says Pedro Campos, principal of Zehren and Associates.
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Since people walk on the roof, the surface and elements such as railings must be up to code.
“It takes very careful planning with a structural engineer so it can withstand (roughly) 150 people,” Campos says.
Often, rooftop terraces showcase planters organized around gathering spaces and captivating views.
“It’s a clever way to take advantage of the site without adding another story,” Campos says.
“In a residential area, it’s really intriguing because it’s where you get the best views — sunrise or sunset or mountain views. It also (creates) an element of surprise, or privacy, where you’re seeing around neighbors, but you’re not able to be seen. You truly feel like you’re on a crow’s nest on a ship; it gives a commandeering view of what’s around you.”
The Alpine Center’s garden rooftop provides various gathering areas, with staircase access on each side.
“It adds a lot of value with a smaller footprint,” Campos says. “It can take on any kind of aesthetic. It can be more classical or more contemporary — with clean, sleek right angles. There’s a lot of flexibility in design.”
However, it does require its fair share of maintenance. Irrigation is critical for a garden roof, and homeowners end up using more water for a garden roof than a green roof. It also requires seasonal cleaning, though the fact that many of the planters are raised means less bending over. Rooftop gardens provide better growing conditions than the ground because they remain a little warmer, due to the surrounding concrete, which tends to warm better than soil, both day and night, Courtens says.
“It gives me the chance to grow things earlier,” he says. “But the process of building planters is pretty complex, with layers of waterproof membranes.”
Other considerations of the High Country’s weather should be calculated when planning a rooftop garden.
“It can be windy, so you have to be careful with it and secure furnishings,” Campos says. “The main thing is, it really needs to be planned integrally; there’s much more involved,” he says. “It’s a whole other ball of wax, but you can have an entire community garden (on a roof).”
A green roof, or living roof, involves a completely different type of design, with more sedum and perennial mixes, which grow year-round. Though rooftop gardens aid the environment, green rooftops offer a “great way to reduce the impact environmentally,” Campos says. Either way, “environmentally, you’re reducing the heat island effect, especially where pavement and homes go up and raise the temperature. Even a rooftop garden is better (than a regular roof because) it’s better to have plants than not,” he says. “ It’s a strategy to lower temperatures and soften buildings (so they) blend into the landscape; it’s a lot softer to look at because it doesn’t have reflectivity or glare.”