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

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Entries in perennial (10)


Coreopsis Perennial Flower: Big Bang Red Shift

This photo is the copyright of Sunny Border Nursery.Most Coreopsis perennials have difficulty surviving winter regardless of the hardiness zone they grow in. Imagine the excitement when a new cultivar was introduced this spring to change that. Red Shift, part of the Big Bang series, promised to be winter hardy. And there was more: The flowers would be large and eventually would bloom in red. And there was still more: The color of this plant would shift from cream to red as the season changed from summer into fall. All that buzz made me grab several pots of this plant when I found them at the nursery. Apart from its other attributes, a red Coreopsis is a rare find.

In early summer, the flowers open in a creamy yellow. Each bloom has a gold button center that is ringed with ruby-red where the petals meet the gold. As the plant matures, the color shifts. On later-opening flowers, the red ring streaks towards the outer tips of the petals. Finally, in cooler weather, newer flowers appear with another color shift that turns them ruby-red. Because this is a long blooming plant, it is possible to have three different versions of the colorations on one plant at the same time. So unique is this phenomenon that no two flowers of this perennial ever look alike. The above image from Sunny Border Nursery aptly illustrates all of the variations.

I am so pleased with the Red Shifts that I planted. This perennial is more than just eye-catching. Every flower bed is enhanced by its presence. In most cases the plant blooms reasonably upright. Unfortunately, the one that I saved for myself was a bit leggy and kneeled towards the sun after it was planted. Being the eternal optimist, I would like to think that this occurred because the plants at the nursery were too crowded and had begun crawling in search of light. Those growing in my clients’ gardens are more upright but not soldier-like. Most Coreopsis plants are sun worshippers; one expects that they will bow to reach for the sun. However, this plant will grow upright and sturdy if the gardener follows the suggestions added in the modifications to this article that appear below.

This new variety will grow 30 to 36 inches in height with an 18 inch spread. As Coreopsis go, the flowers are huge, measuring 2 inches across. This is a floriferous plant, a heavy bloomer from early spring until fall. Of course, dead heading improves the continuity of bloom. The plant is hardy from zones 4 to 8 and I can hardly wait until spring to test its touted hardiness. It prefers sun, a well drained soil and is drought tolerant. It attracts butterflies as well. Above all, its unusual color variations allow it to blend easily into most gardens. I didn’t expect red to work in my English style gardens, but it did. The cream coloration made it happen.

December 3, 2009. I have just received an e-mail from the breeder of this plant, Darrell Probst, offering  additional information about winter hardiness and stem sturdiness. Winter hardiness is directly related to the number of rosettes that will have formed at the base of the plant in the fall. The more rosettes, the better the plant will be able to sustain the winter. Regarding the stems: the more sun and the fewer rosettes that it starts out with in the spring, the sturdier the stems will be. In the spring, thin out the rosettes at the base. The remaining ones will be sturdier and will bloom the longest.


Comtesse de Bouchard: a Pink Flowering Vine for the Perennial Garden

Problem solving is an exciting aspect of perennial gardening. When my neighbor installed a swimming pool last season, municipal by-laws compelled him to secure his back yard. He chose to surround his property with a beige-colored vinyl mesh fence. My challenge was to camouflage that portion of the fence that divided our two properties.

The  plan was to cover the fence with flowering vines. I began the project by planting bluish-purple Clematis Durandii, purple-blue Clematis Jackmanii and vivid mauve-blue Clematis Elsa Spath.

This selection established a richly colored background to showcase perennials that would ultimately grow in front of the vines. Once the blue-purple theme was in place, I found an on-line supplier from whom I was able to purchase 2 unusual flowering vines: Schizophragma hydrangeoides Moonlight, with white flowers and Schizophragma hydrangeoides Rosea, blooming in pink. These arrived by mail, rather small in size, grew very little and did not bloom this first season. However the Clematis vines were mature when I bought them and they bloomed impressively.

The Clematis are happy in their location because the upper portions get sun and the roots are shaded by the perennials. Now that I see how well they have grown here, I am ready to kick it up a notch, so to speak. Next spring I plan to insert cyclamen-pink Clematis Comtesse de Bouchard between the purple-blue Clematis to create additional color drama. I understand that the pink petals might fade in the afternoon sun. I’ll take that chance. I have 40 feet of fence to cover and experimenting will be fun.

Comtesse de Bouchard belongs to that class of vines that needs trimming in the spring because it blooms on new growth. The truth is that I have never trimmed Clematis in the past. I want the vines of the previous season to act as supports for the following year’s growth; in winter, these now-brown bushy vines offer textural interest to the garden as well. Some gardeners report that Comtesse needs hard pruning. I wonder if it’s because the dense and heavy vines threaten the integrity of their support structures.

This pink Clematis was chosen because it is one of the most popular vines of its species. It produces flowers 5 inch wide. The petals, the texture of crêpe paper, appear to smother the vine in pink. It blooms from midsummer until early fall, in sun to part shade; it is hardy in zones 4 to 9 and can reach a height of anywhere from 6 to 12 feet. Some growers even report success growing this cultivar in full shade.

Because it is dense and heavy, it needs a strong structure for climbing. Trellises made of light-weight wood are too weak. A sturdy fence, an arbor or a pergola are all ideal supports. Like most Clematis, it will require help to establish itself upright for the first few years. Then, the previous season’s vines will trap some of the upward reaching new growth. The gardener will only have to assist part of the vine to climb. I am fortunate that my neighbor sunk his fence posts into reinforced concrete for strength and chose vinyl wire mesh fencing. The wires eliminate the need for cord or stakes to support my vines. All I need to do is to insert a petiole into the mesh. By naturaly twining itself around the wire, the petiole will keep the vine growing in an upright direction.


Meet Aster Alma Potchke, a Late Season Perennial

This hardy New England Aster grows 3 feet tall in zones 3 to 8 for about 4 to 6 weeks during September and October. Its intense magenta-pink flowers, offset by light gold center eyes, will electrify the autumn garden. For best results this plant needs a southern exposure; otherwise it will kneel and crawl to follow the sun. Once it kneels, it cannot be straightened out. Once it starts crawling, it cannot be returned neatly to its upright posture. If there is no southern location, it is worth investing a few minutes to stake the plant in early July to prevent the kneeling and crawling. When staking, ensure that the stems are not crowded together. Leave a lot of room for air circulation around to prevent mildew.

Some gardeners dislike the legginess of this impressive plant. This Aster sheds leaves at its bottom to expose its stalks. These naked ankles may be camouflaged by planting mid height perennials to hide the view.

Aster Alma Potchke is not invasive and it is not an aggressive spreader. As long as it grows in an upright position, it will not appear messy as some other Asters and Chrysanthemums do. By the third year, it may become necessary to reduce the size of the plant. This is easily done by slicing through the root ball to remove excess growth.

While this is not a totally carefree perennial, the extra attention that this plant may require comes with a big payoff. Gardeners will be rewarded with a tall, intensely colored, plant that puts on a bold performance in the autumn garden. When it grows upright it is majestic.


Scintillating Sedum: a Succulent Perennial

Of all the perennials that I have planted in my clients’ gardens so far this season, the one that seems to attract the most attention is Sedum “Frosty Morn’. This is an unusual plant because its foliage is incredibly attractive to the eye. The center of each leaf is shaded silver-blue-green with wide margins of cream. The combination of these two colors creates a shimmer that tugs at the eye. It’s hard to glance away from it. Unlike most other Sedum that do triple duty as specimens of architectural foliage, bright autumn floral displays, and a drought  resistant nature, this variety is grown mostly for its foliage. Its  flowers are non-descript.

I deliberately do not use this perennial as a specimen. I insert it into foliage compositions of jade-green Sedum, silver-blue Artemisia or Dianthus and purple Sedum. Somehow it becomes the glue that binds these collections together and enhances all of the other plants simply by growing among them.



Bergenia, the Perennial with the Patent Leather Leaves

Plant green leather and watch what it does to the texture story in the garden.Bergenia cordifolia, is a leathery-leaved, part-shade perennial that prefers moist soil. An elegant glossy leafed plant, it serves as a great foil for the silver-freckled foliage of Pulmonaria, feathery Astilbe, multi-green Hosta or the enchanting Heuchera Hercules. Plant several of these perennials together in a shade garden to create a symphony of textures..

In early spring, Bergenia produces purple, pink or white flowers. It is disappointing that the visual impact of this perennial is not evident for the first few years, especially if one purchases a small-sized plant. Perhaps that is why it is not used more widely. It’s worth being patient because a mature clump of Bergenia can produce a rich, almost iridescent, flower bouquet, when very little else is blooming in the garden. In autumn, its evergreen leaves may turn bronze or red, adding its own drama to the changing of the leaves. Bergenia is hardy in zones 4 to 9. Depending on the cultivar one chooses, it will grow from 8 to 24 inches in height, and from 1 to 2 feet wide.