15 rooftop plants that will elevate your garden
Choosing rooftop plants is much like choosing plants for any garden. Plants must be able to grow in the growing conditions you have available, on a roof, where they may be exposed to intense sunlight that bounces off nearby buildings or can often be shade from those nearby structures. Rooftop gardens also tend to have limited space, but you may also need taller plants that can act as living screens. The following list of rooftop plants offers something to suit any noble situation.
Hardy to Zone 5, Dogwood Kousa (Cornus kosa) They remain small for a tree, with some varieties reaching only about 30 feet tall, making them an excellent foundation for a rooftop garden. In spring, the tree has small but pretty white to pink flowers, which transition to deep green foliage in summer. Autumn offers its own benefits, with purple-red leaves and fruits (which begin to appear in August).
Harry Lauder walking stick
A deciduous shrub with an unconventional common name, Harry Lauder Walking Stick (Corylus avelana “Contorta”) twists itself into seemingly unfathomable shapes that serve as fine sculptural botanical accents for a rooftop garden. The heart-shaped foliage on the shrub or small tree, which can reach 10 feet tall and is hardy in zones 4-8, is also interesting.
Juniper ‘Blue Star’.
It is also called single-seeded juniper. Juniper scales ‘Blue Star’ sparkles with thin needles with a pronounced silvery-blue cast. Hardy in zones 4-8, this low-growing juniper reaches about 3 feet tall and makes a good accent or container variety for rooftop gardens.
Dwarf hinoki cypress
Fan-shaped foliage and yellowish-green color are notable characteristics of the golden dwarf hinoki cypress (Chamisiparis is obtuse “Nana Lotia”). Extremely slow growing, this evergreen tree will only reach 3 feet tall at its mature height. It needs a regular watering schedule but is otherwise wonderfully low care. Hardy in zones 5-9, the evergreen brightens corners in a rooftop garden or works well with other plants in container sets.
Ideal for the shadiest areas of the roof, Astilbe ‘Fanal’ rewards gardeners with its rich crimson bloom in midsummer (usually July). A good mid-border perennial, astilbe shoots stems about a foot and a half tall and is hardy in zones 3-8. It does best in moist soil. Do not allow astilbe to dry out or its leaves will look wavy and torn.
Incorporating hostas into shadier spots in a rooftop garden is a great way to add beautiful foliage to a space. Most species are hardy in zones 3-8, and come in a range of colors and sizes so you can mix and match them to best fit your rooftop garden design.
With the brain
Also called bug weed, ajuga (Aguja Reptans) is a flowering ground cover that attracts butterflies and hummingbirds. This perennial needs regular watering on rooftops but its low growth makes it a good choice for hotter situations. ‘Silver Beauty’ (shown here) is one good choice, as is ‘Bronze Beauty’ which has deep blue flowers and bronze-tinged foliage. Ajuga is hardy in Zones 3-9.
Loved for its scent of English lavender (Lavandula angustifolia) is a member of the mint family and native to the Mediterranean region, so it tolerates the windy and dry conditions of a rooftop garden well. Its beautiful gray-green foliage reaches about a foot and a half in height, making it well-suited for containers or full rooftop garden beds. It is hardy in Zones 5-9.
Most daylilies are fairly hardy, and their prolific blooms provide rooftop gardeners with a good way to add color to full sunspots. They come in a wide range of sizes and colors but in general, the foliage reaches a height of about 1-2 feet. Most daylily species are hardy in zones 3-9.
Well suited for low-growing borders or the front of flower beds and lamb’s ears (Byzantine Staches) It has a distinctive soft, feathery texture to its silvery-gray foliage. It tends to spread into the ground, so it may be best for containers in rooftop gardens in Zones 4-10. If the purple flowers become leggy in the summer, cut them off and new flowers will often form.
With fragrant flowers that droop like grapes, showy wisteria is a hardy, woody vine. Wisteria ‘Blue Moon’ is more rewarding with three blooms per growing season; The plant is hardy in zones 4-9. Its wandering vines are a wonderful accent on a trellis or rooftop garden.
Honeysuckle ‘Golden Flame’.
This variety of honeysuckle (Lonicera × Hicroti “Gold Flame”) is a great way to attract hummingbirds and butterflies to your roof garden. It begins blooming in late spring, with delicate pale pink to deep purple flowers that are incredibly fragrant. Hardy in zones 5-8, the honeysuckle vine reaches about 20 feet tall, making it well-suited for a trellis or atop a rooftop porch structure.
Creamy white flowers adorn the vines of this self-clumping plant, which can reach an impressive 60 feet tall. However, climbing hydrangea (Hydrangea petularis), Hardy in zones 4-8, it is easy to prune and rewards with spring flowers as well as a stunning fall color shift, when the green leaves turn bright yellow.
Ornamental grasses are hardy, low maintenance and provide year-round interest. These grasses also make excellent rooftop plants and blue fescue (Festuca glauca) It is one of the best for this use. It stays shorter, at only 10 inches tall, so it does well in containers and holds up well in windy conditions. It is hardy in Zones 4-8.
On the other end of the ornamental grass size spectrum, incense herb, in particular, can reach 7 feet in height Miscanthus sinensis “Gracelimus.” It does best in full sun and can be used at the back of a rooftop garden border or as a screening plant for an unsightly view. It is hardy in Zones 5-9
Seedweed, also known as Chinese silverweed, can be invasive in some areas So check local restrictions before planting them.