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

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Entries in long blooming plants (2)


Thalictrum Hewitt’s Double is a Singular Sensation

Thalictrum Hewitt's Double floating over the partially spent September flowerbed.The tall, frothy Thalictrum that grows in the flowerbed on my front lawn is in its third year of maturity. As one can gather from the photo, it is a conversation piece. Everyone thinks that it’s a tree. No visitor to my home, or neighbor on my street, has ever seen such a delight for the eyes. It touches the admirer in a profound way.

I first discovered Thalictrum, the species, about 18 years ago, when I purchased over 100 seedling perennials, all of which had plant tags that indicated  flowers in pink or flowers in blue. At that time, Thalictum aquilegifolium, was an unknown entity to me. However, since it promised to provide pink blooms, I added it to the assortment, without a second’s thought. I was eager to be surprised.

Over the years, this species perennial, a very different-looking plant from the Hewitt's Double variety, would grow successfully and fully easy-care in my back yard garden. Tall and upright during the months of June and July, its stately, elegant pale salmon-pink plumes appeared iridescent in the shade but faded in bright sunlight. These feathery heads added an ethereal mood to my garden. When allowed to grow and mature without propagation, they created a grove of pastel softness suitable for any fairy tale illustration.

The species delivered such an impact to my soul that I was motivated to seek out other varieties. Almost 15 years later, A. Hewitt’s Double, a Thalictrum with a longer bloom period  [June to late September] appeared in some nurseries and I decided, this time, to plant it on my front lawn, where growing conditions seem to pamper perennials more than my back yard does. I expected some similarities with the species, but those are few.

Closeup of Hewitt's Double flower head.One characteristic that sets this plant apart from others is its translucent lilac colored flower heads. They scintillate in sun – especially when they are backlit – and glow in part shade. These visuals create a nearly supernatural mood in the garden. What a bonus!

Another unusual characteristic about Hewitt’s Double is that it cannot grow upright, even with the help of heavy-duty stakes, which are unquestionably necessary. Its flower heads grow in such a precarious position, that heavy rain and strong wind will cause the heads to crack off from its otherwise formidable stalks.

Up until this year, I expected that staking the plant in a delphinium style, i.e., one very tall support behind the plant, would be sufficient to keep it from buckling over. It wasn’t!  By the end of summer, I had added an additional three stakes behind the first, each one taller and thicker than the last. None was able to prevent the plant from bowing over to catch the sun. And combined, they were no match for nature's pull.

Because several tall broomsticks together were no match for the pull of this plant, I resorted to using a one-inch wide steel I-bar, 6 feet tall. The perennial became upright as soon as I inserted this metal stake into the earth with the help of a mallet [it took at least 200 whacks to secure it in place] and tethered the plant to it. For that solution, I must thank my lawn service staff who came up with the idea and gifted me with this repurposed steel object.

Especially when held upright, an astute garden designer may have noticed in the posted image that the proportions of this perennial are not suitable for both the narrow width of the flowerbed and the height of the neighboring plants.

Hewitt’s Double towers awkwardly over the other perennials because none of them grow tall enough to anchor or integrate it into the color scheme. This impression, of one plant floating above the others, while it creates movement, also creates instability which makes me uncomfortable. That is reason enough to lift and place it elsewhere.

The rose patch that grows directly behind this flowerbed, and up against the elevated veranda, appears to be a better location. I intend to move the Thalictrum to the left of the pink Rose Bonica that appears in the far background.

I hope that both this rose, along with Rose Carefree Wonder to its right, will provide sufficient height, volume and shape to weave Hewlitt’s Double into the overall garden design. I expect that the iridescent lilac color of this unusual perennial will appear enhanced and even more amazing when it blooms next to the rich baby-pink of rose Bonica.


I’ve Got the Camp-anula Glom-erata Blues!

Campanula glomerata, the species, from glomerata, the species, planted over fifteen years ago, is gone. In a garden where neatness was paramount, it was an unwelcome visitor. It appeared messy in a new flowerbed that was barren and sparse, because all of the infant perennials were too tiny to fill up negative spaces. Furthermore, it self-seeded beyond my ability to control it. In addition, it sprawled all over, spread too quickly, bloomed for only two weeks, which is too short a time, didn’t look impressive, and didn’t project from far. Eventually, it was discarded when I found it wanting. I was happier gardener without it.

Today, my garden is filled with mature, stately perennials. There is less room for plants to self-seed. Large swaths of pastel colored flowers, that over time filled in the sparseness, are now better able to benefit from a  campanula's blue flowers. Furthermore, the hard-packed earth of yesteryears, that made maintenance a challenge, has been amended so that it is soft and workable. Plant spread is easier to control, seedlings are easier to dig out, and there are enough stately perennials in the bed to enhance lower growing plants.

I've begun to give Campanulas another chance; after all, they are blue - my favorite color. Two new varieties of Campanula glomerata attracted my attention. However, I am skeptical about the long term because I am not a diligent deadheader and that is what is required to keep the plants blooming throughout the summer.

Campanula glomerata Superba from Seemnemaailm.eeTwo years ago, I planted Campanula glomerata Dahurica in a client’s garden and I was happy with its performance.

Campanula glomerata Freya from Last year, I planted Campanula glomerata Freya in my own garden and was more than pleased.

A one and two year span is too short a time for a gardener to report definitively about these plants. Therefore, all I can share is that they appear to be neat, they bloom for two or three months, and they make me very happy. The technical information about them, that follows, has been gleaned from the trade.

Campanula glomerata Superba from Robsplants.comCampanula glomerata dahurica 'Superba' has bell shaped flowers that are purple-blue with a glistening almost metallic sheen; they are borne in clusters atop stalks twenty inches tall above the basal foliage. Its thick, low growing and spreading clump should be dug up for division every third or fourth year. Promising to bloom from May to July, if spent flowers are deadheaded and foliage trimmed, the leaves will usually induce a second flush of flowers and the plant will be less likely to reseed vigorously. This sun-loving perennial will be long-lived only if it receives regular irrigation, as it is not drought hardy.

Campanula glomerata Freya from Whiteflowerfarms.comCampanula glomerata Freya is shorter than Dahurica; it grows only sixteen inches tall. However, blooms make up about two thirds of its height. Instead of bells, full clusters of small star-shaped lilac-purple flowers are borne almost all the way up the stems. Unlike other glomeratas, this variety is more floriferous. Like other glomeratas, it requires dividing every three to four years and spent flowers must be deadheaded. It is sturdy, non-invasive, and compact. While this perennial may be planted in full sun or part shade, it grows taller in the shade. At this time, there is no consensus on how long Freya will bloom. Some promise that itwill flower continuously from May to August, some say May to July, and others report May and June. Mine need another season before I can report accurately on this subject.