But, of course, the traditional way to propagate the best named delphiniums is from cuttings, that was the method used for so many of the fine plants seen towering at the back of traditional British herbaceous borders over the years. The problem is that individual delphinium plants produce so few cuttings that, again, they can be expensive to buy a nd uneconomical for nurseries to produce.
But now there is another form of vegetative propagation that will guarantee top quality: tissue culture. Plants in the buttercup family (Ranunculaceae) have been famously tricky to propagate in the laboratory by tissue culture but now Clematis are routinely produced in this way, along with some hellebores, mainly hybrids of H. niger. There has not been success with Aquilegia, Hepatica or Ranunculus but a few - just a few - delphiniums have yielded to this technique.
The first of the Elatum Hybrids to be tissue-cultured were the pink-flowered cultivars, the University Hybrids, developed in a long-running breeding program by Professor Legrow, and concluded at the RHS Garden at Wisley. The first, Princess Caroline (‘Odabar’), was launched at the 1994 Chelsea Flower Show and, although a poor garden plant, its availability through tissue culture led to its widespread use as a cut flower. It was followed by ‘Red Caroline’(above, click to enlarge), ‘Red Rocket’ and ‘Coral Sunset’.
Much more recently the Highlander Series has become available. Developed in Scotland by Tony Oakley, this is a new series of five cultivars with a superficial similarity to one of my favorite of all perennials, ‘Alice Artindale’. Each sterile flower is fully double, with about fifty slender petals creating a flower like a frilly button. The flowers are carried in spikes of about thirty or more and five cultivars are currently available: ‘Blueberry Pie’ (deep lilac with a green center), ‘Crystal Delight’ (a very frilly pale lilac with a yellow-green center - right), ‘Moon Light’ (pale lilac bordered in blue with green center), ‘Morning Sunrise’ (white with a green center), and ‘Sweet Sensation’ (deep mauve-purple, tinged with blue-green). Without tissue culture they would be almost impossible to buy.
So, as we think about buying delphiniums, we must choose: pay the proper price for a really good plant, or buy a second rate plant for a cheap price. There’s only one answer, really. One really good plant is worth any number of second rate ones and now, with tissue culture, good plants are becoming easier to buy.
In the UK, a wide range of superb award-winning cuttings-raised delphinium cultivars is available in limited numbers from Larkspur Nursery Plants of the Highlander Series are available from Hayloft Plants and elsewhere; Princess Caroline (‘Odabar’) and ‘Red Caroline’ are available Burncoose Nurseries. In North America, even tissue-cultured delphiniums are very hard to find although ‘Crystal Delight’ (Highlander Series) and ‘Coral Sunset’ are available mail order from Hirts. There are clearly some great opportunities for mail order retailers.
* This is the second part of a piece entitled Buying Good Delphiniums which appears in the current issue of the Newsletter of the Ranunculaceae Group of the Hardy Plant Society. Anyone with an interest in hardy plants in the Buttercup Family (Ranunculaceae) should join. The first part was posted here in April.