C. 'Vyvyan Pennell' producing dense blossoms in full sun, May 2020. In February 2021 the pussy willow looming behind would land on the row of double-flowered cultivars with extreme malice.
Given the influence of this month's selection, and the impact of Pennell's Nursery upon the clematis trade in the mid-to-late decades of the last century, it's a wonder C. 'Vyvyan Pennell' has only now become a Clematis of the Month. In his 1989 book Clematis, Barry Fretwell credits Pennell's Nursery with helping to lift clematis from the doldrums when they embarked on concerted breeding work with the genus in the 1950s. Pennell's pursued the first breeding line to introduce lavender/purple filaments to the color roster of clematis flower parts, with both C. 'Richard Pennell' and C. 'Walter Pennell' in 1974. Their previous introduction, 1959's C. 'Vyvyan Pennell', was a parent in both cultivars. The success of C. 'Vyvyan Pennell' has carried forward into such "modern" favorites as C. 'Dorothy Tolver' (1993) and C. 'Bieszczady' EARTHQUAKE in 2006. It is no exaggeration to say the double form of C. 'Vyvyan Pennell', produced on old wood in mid-spring, is opulent. The inner petaloid sepals are often nearly as long as the outer sepals and are generously abundant. The full expansion of the flower can take two weeks, giving the impression of a lengthy bloom period. The initial color when double might be what is meant by the word “mauve”, which to my mind is dusty rose lavishly tinted with lavender, but by the time the double blossom has nearly finished its performance, the overall shading has gone distinctly blue, as pictured here in a specimen waiting to be planted.
Unlike some spring double clematis, such as C. 'Louise Rowe', which may produce double, semi-double, and single flowers as the season progresses, the later flowers of C. 'Vyvyan Pennell' are most often single, and of a more violet hue than one would guess. One might not know it for the same cultivar! There are those among us who prefer the simplicity and depth of color of the single version over the double. In partial shade, C. 'Vyvyan Pennell' will flower well enough, but will be more rangy in habit than the advertised 2.5 to 3 meters (8 to 10 feet), and the double flowers will have a more anemone-flowered form, with the petaloid sepals displayed as a central tuft, although more filled out than spikey doubles such as C. 'Multi Blue'. In late winter do not remove more than ½ the length of the vine and fertilize with a heavy hand to produce the most luscious flowers. If, as mentioned above, you prefer the single form, you may whack away with impunity, hard pruning to a third of a meter, although you'll wait a little longer for the first batch of single flowers, and your specimen may try to slip in a semi-double flower or two.
The International Clematis Society was delighted to see C. 'Vyvyan Pennell' giving a good account of itself at Healey's Cyder Farm in Cornwall.
The double flowers age to blue, or something like it.
Of course sometimes nature does the pruning for you. The plants of C. 'Vyvyan Pennell' at the Rogerson Clematis Garden were crushed by a 10-meter tall pussy willow coated with several centimeters of ice. They took the brunt of the weight of the multi-trunked base. After the woody carcass was removed, all three clematis were cut to the ground. They rebounded with handsome lengths of single blossoms in time to join their neighbors for peak bloom in the middle of a heat dome. With ample water, the single blooms of C. 'Vyvyan Pennell' withstood three days of record heat, 42°C climbing to 43.8°C, and peaking at 45.5°C. From crushed ice to a bake oven, C. 'Vyvyan Pennell' performed unfazed.
Being scrunched by a behemoth pussy willow and of necessity hard-pruned did not prevent a charming array of single blossoms on the hottest weekend on record in the greater Portland area.
In the author's garden C. 'Vyvyan Pennell' and C. montana hybrid 'Jenny Keay' (syn. 'Jenny') flower together in the shade of a Magnolia stellata, star magnolia.