My husband used to get alarmed by the detailed plant lists that I make at this time of the year. It’s no wonder, really. Lengthy, detailed and involving huge expenditures, the lists are a two-dimensional harbinger of bankruptcy. I compile them while in the throes of catalog fever, an affliction that I catch on contact every January after exposure to the various vendors’ spring offerings. There is no vaccine or antidote, though the sight of an ominous checking account balance can reduce the symptoms. Eventually the fever passes, a semblance of common sense returns and the lists get whittled down to a more appropriate and fiscally sane size. My husband keeps calm during the worst of the fever, but I knew he breathes a sign of relief when it’s all over.
The list-making has begun for the year and at the top is a new hybrid plant, christened Digiplexis Illumination ‘Flame.’ “Digiplexis” sounds like either a muscle or a machine to exercise muscles, but it is actually a hybrid of two closely related plants. One of them is foxglove or digitalis, known to just about every gardener and flower lover. The other is the less well-known isoplexis, which hails from the sunny Canary and Madeira islands and is best described as foxglove’s shrubby cousin.
The best-known of the three isoplexis species is the Canary Island foxglove or Isoplexis canariensis, which grows to 5feet tall and 3 feet wide and bears yellow, red or orangey brown flowers. Unlike individual foxglove blossoms, which are fused into tube shapes with an enlarged lower lip, isoplexis blooms feature pointed petals of equal length, fused at the base. The shrubs are sparsely branched with narrow leaves.
The marriage of digitalis and isoplexis was arranged by plant breeders at the English seed and plant house, Thompson & Morgan. The new creation is classified as an “intergeneric hybrid” because the parents belong to different genera within the same plant family. As with many intergeneric hybrids, the plants are sterile, producing little or no seed. This is another change from foxglove, which tends to self seed readily.
Catalog copy is notoriously light on details, some of which are important. Perhaps the most significant detail about ‘Flame’ is that while it is heat tolerant, it is much less winter-hardy than common foxglove. Foxglove is hardy in USDA zones 3 through 8, meaning it can survive minimum winter temperatures as low as -35 to -40 degrees Fahrenheit. ‘Flame’ digiplexis is hardy in USDA zones 8 through 11, meaning that it can only survive minimum winter temperatures of 10 to 15 degrees Fahrenheit. My area, .located in USDA zone 7a, is technically outside the hardiness range for digiplexis. However, I may try it anyway in a protected spot with a lot of mulch for winter insulation. “Pushing the zone” and growing plants not technically hardy in a specific area is something of a competitive sport among gardeners.
Another ‘Flame’ feature that gets short shrift in the catalogs is its growth habit, which is closer to the shrubby isoplexis than the herbaceous digitalis. The plants develop woody bases and the clumps increase in size over the years. Presumably ‘Flame’ can be divided successfully if it gets large enough to exceed the boundaries you set for it. The dimensions given are about 3 feet tall by 1.5 feet wide. This makes it a good subject for large containers as well as garden beds.
‘Flame’s’ selling point is the big, colorful foxglove-like flower stalks, glowing with individual flowers that combine sunrise shades of yellow, peach and rose. They look like they would be wonderful for cutting, though their longevity in a vase is still a mystery. According to the catalog copy, the plants flower repeatedly from spring through frost, sending up new shoots throughout the summer. I am only guessing, but I would suspect that digiplexis, the offspring of a sun lover and a part shade lover, is somewhat less shade tolerant than foxglove. Planting it in a sunny, protected spot is probably the best bet, though if that spot receives a bit less than the 6 hours per day that is standard for real sun lovers like roses, it will probably be fine.
Should you buy this flashy newcomer, whose good looks have wowed customers at industry trade shows? At a retail price of about nineteen dollars plus shipping and handling, it is not inexpensive. On the other hand, as flashy investments go, it is a lot cheaper than a new sports car. The jury is still out for me, but Digiplexis Illumination ‘Flame,’ with its febrile colors, is securely on my fever-induced spring plant list. We’ll see if it still looks alluring when the fever subsides.