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Allan designs and plants flowering gardens in Montreal, Zone 5 [USDA Zone 4] .

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Entries in rooftop gardens (2)


Plant Gardens in the Sky; a book review about penthouse gardening

Roof Terrace Gardening, Michele Osborne, Aquamarine.

Gardening in the sky is not a novel idea. As far back as 600 or 500 BC, the Babylonian king Nebuchadnezzar ordered the construction of urban hanging gardens to please his wife, saddened when she was separated from the plants of her homeland.

Today, many urban dwellers choose to incorporate adjacent rooftops into their living spaces. Here, on these very desirable roofs, terraces, and balconies, they create lush outdoor gardens that enhance the quality of their lives by adding a natural balance to city living.

High above the bustle of densely populated areas, urbanites living in these privileged spaces are able to experience air that seems purer, a sense of freedom and privacy, brighter daylight, infinitely more sunlight, and closeness to nature that is often associated with mountaintop experiences. At these heights, people are more likely to be aware of the ever-changing shapes of clouds, the colorful drama of sunrises and sunsets, and the majesty of thunderstorms.

With strategic planning, apartment dwellers that are fortunate enough to include a rooftop into their living quarters, a concept sometimes known as a penthouse, can enjoy many of the benefits of a garden. However, the approach to achieving a quality outdoor life, high above a densely populated urban area, requires an approach different from that used to create a bucolic retreat in a back yard or on an estate.

A rooftop garden design must take into consideration building and zoning regulations, structural integrity of the apartment building, irrigation and waterproofing, physical access for both enjoyment and maintenance, and weather elements that are harsher at great heights than they are at street level.

In this very practical mass-market publication, the author offers a variety of inspiring design ideas that meet the needs of most aspiring rooftop gardeners. Readers will learn how to plan a design for a multipurpose outdoor space that takes into consideration one’s needs for entertaining, relaxation, play, and contemplation.

The author has also includes suggestions for furniture, containers, ornamentation, lighting, water features, and the selection of plants. Readers will be guided into choosing vegetation, not only for beauty, but also for privacy, shade, accents, visual background filler, and for growing food. The plant recommendations are influenced by the ability of certain vegetation to withstand the exposed, harsh conditions associated with windy, sun drenched rooftop gardens.

Michele Osborne graduated from the Sorbonne in Paris as a linguist before moving to England. There, her passion for art and architecture inspired her to become a landscape designer. Working privately and with developers and architects, she has completed projects both in England and abroad. 

Designing many roof terraces in London's East End and Docklands allowed her to discover views of the city, which she found so exhilarating that she decided to abandon her Victorian terraced house in favour of a converted telephone exchange, where she could build her own roof garden. She is a winner of the prestigious Guardian's Britannia Home - builder's Award for "Best Landscaping" and her work has been exhibited at the Museum of Garden History in London.



Succulent Jade Garden Sculptures with Hot Pink Trim a plant that needs no irrigation beyond its establishing year. Instead of the gardener, nature is its primary caregiver. That right!  Simply plant it and forget it, even if the soil is clay. Welcome to the world of the no-care perennials of the Sedum family. Swollen, succulent foliage, resembling jade sculptures in both color and texture, enable these plants to withstand extended periods of drought and neglect. A shallow root system and water conserving habit also make this plant an ideal candidate for use in rooftop gardens.

Overhead shot of Sedum Carl in a client's gardenSedum will not interfere with any gardening scheme as it blossoms when most other perennials have completed their flowering cycle. Throughout the season, it supplies a neat, semi-gloss texture to garden compositions; the forms of the upright varieties resembls serene broccoli-shaped flower bouquets that seem to ground the flamboyance of other plants around them.

Alternating Sedum Carl and Hosta in the first season of a planting.Allowed to remain intact for the winter, its dead heads provide visual interest to gardeners and food for birds. As a design element in the garden, this plant is one of my favorites. Strategically planted, it may transform any messy flowerbed into an attractive, interesting garden composition.

However shade, wet soil, and a placement unaligned with the sun, will prevent this plant from performing impressively. Some believe that it will grow successfully in shade. That is stretching the point. While it may grow in reduced sunlight, it does not thrive there with the same robustness that it displays in a sun-filled location. In addition, wet soil will cause its root ball to decay. A sunny, well draining placement is best. Fastidious gardeners should bear in mind that some varieties of this, otherwise upright, disciplined plant might sprawl horizontally if they are not aligned with the sun’s path.

I found a Sedum plant of unknown pedigree in the first garden I tended. A neighbor, who previously had owned our property, placed it there. When I mentioned how much I admired this dignified plant, and asked where I might find another, he dug up mine, sliced the root ball in half, and handed me two plants. When a rootless stalk of one of the newly propagated Sedum fell away, he inserted it into the soil, like the peg of a tent tether, promising that it would grow into a third plant that same season. It did!

The Sedum propagating trick took place almost fifty years ago. Since then, the lone plant that I found in my flowerbed has generated hundreds of gift plants for anyone who admired it.

Recently, a client installed a new front walkway and asked for suggestions how to landscape around it. The first, and most effective, treatment did not sit well with her. Originally, I recommended bordering both sides of the walkway with small round boxwood shrubs, to delineate the concrete  from the grass. When the client found the round, neat shapes of the Buxus too severe, we agreed upon a treatment of alternating mid-height Sedum with low growing Hosta. The images above describe the final plan.

At the time, I could not propagate sufficient Sedum in my garden to complete the project, nor could I locate more of the same. The name of the strain growing there had always been a mystery. Therefore, I had no chopice but to select stock from among the newer varieties currently offered by the trade. I chose Carl, [a.k.a. Karl]  because it was the tallest Sedum available that season.

However, I had not expected Carl’s florets to bloom in a color so impressive. The almost-iridescent, dark, fuchsia-pink [a.k.a. magenta-pink] was a welcome change from the duskier shade, usually associated with Sedum. In the end, I was pleasantly surprised with the color impact that Carl created and the client was delighted with her newly trimmed walkway.