Once seen, the stately beauty of well-grown British delphiniums will never be forgotten. Nothing in the garden among herbaceous perennials can hope to rival the colors, the size and the presence of a delphinium elatum hybrid.
The Breeding of Award-winning Delphiniums
Delphiniums are perennials that are native to many regions throughout the world, with Australia and the Polar Regions the only areas apparently lacking this charming plant. In their native setting, most are found in the mountains. Although over 300 species exist within the genus delphinium, the most widely hybridized form has been the species elatum.
Historically, delphinium elatum was hybridized as early as the 1500’s. Initial breeding work was principally accomplished among professional gardeners, but within the last half century, amateur gardeners dedicated to this plant have been almost singularly responsible for continuing the breeding work on these plants. Plants are crossed, seedlings grown, more crosses are made and on and on it goes, with careful selections made based upon strict criteria for color, size, shape, vigor and durability. The work these dedicated gardeners have accomplished has led to the development of plants characterized by tall, tapering spikes of flowers, often-reaching 6 feet or more. The color range is broad, excepting a very recessive yellow and no orange and red. The years of breeding have led undeniably to some of the most awe-inspiring flowers we have available today.
Following the painstaking breeding and seedling selection process, the best of the young delphiniums are trialed at the Wisley trial gardens for several years. These trial gardens, sponsored by The Royal Horticultural Society, are internationally recognized and have a long and acclaimed history of outstanding contributions to the horticultural profession. The plants in the trials are painstakingly observed by professionals and are ranked on very specific criteria. It is only after this extensive process that a plant may ultimately be selected to receive the prestigious Award of Garden Merit. Such selections are then introduced to the gardening public as named cultivars and afterwards, are only reproduced vegetatively. In this way, exact clones of the award-winning delphinium selection are produced.
Unfortunately for us, British delphiniums are only available in the United States from hand-crossed or open-pollinated seed. Specific cultivars are not available because the plants are not bred here and they cannot be shipped here due to quarantines and inspection requirements. Gardeners however can obtain seed from the Delphinium Society and raise the plants from seed each year. Fortunately the wait for a bloom is not long, as the plants produce bloom about 41/2 months after the seeds have produced their first set of true leaves. And yes, they are hardy in most of Maine and probably, in all of Maine where there is a reliable snow cover.
The Successful Culture of Delphinium in Home Gardens
Growing delphiniums is relatively easy, as long as one accepts certain gardening responsibilities. On the one hand, they require a bit more care and attention than most other herbaceous perennials but on the other hand, there are no mysteries for achieving success with them. A green thumb is not a prerequisite. The Delphinium Society members gladly share their experience gathered over the past 60 years, so you may remain calm and confident knowing that there is an excellent support group standing ready to make you a champion of the British Delphinium.
Here is how we learned.
At Plainview Farm, we planted several young delphinium seedlings in one of our display gardens. We went into this enterprise with the expectation of another hopeless delphinium experiment as had been tried so many times with the Pacific hybrids. Death at the hands of winter was a certainty! Well, the doomed seedlings were placed in a sunny and rather windy site and were planted in relatively heavy soil with no amendments. In other words, if this experiment was to work, it had to be on our terms. No special attention was provided.
The next spring, these plants emerged unscathed and in July, we were graced with the most spectacular blooms we had ever seen. There they stood, growing in our garden having defied a nasty winter and, admittedly, blatant neglect. Five feet of plant, with the top 30" being a dense, tapered spire of deep blue and looking gorgeous. That was five years ago and the plants remain to this day. One can only imagine what might have happened if we had cared for them!
Delphiniums are generally easy to please. With regard to soil, they can be grown successfully in clay, gravel or loam, as long as it is well drained. Their tolerance of wet soils is minimal and it is this condition above all others which typically kills them. Measures taken to prevent waterlogged soil, particularly in the late fall and early spring will go far to keep the plant healthy and productive. Provide full sun, routine watering and supplemental fertilizer at least two times per season and you will have set the stage for spectacular flowers.
Staking is necessary because the heavy blooms will break from the weight of rain and the violence of the wind. An annual application of compost is always advisable. Cutting back the flowers after bloom and then cutting the stems back to one inch above ground after the leaves have withered will promote the establishment of numerous eyes for the following season.
The practice of thinning the plant can be the most difficult since it requires the removal of growing stems, a task most gardeners flinch at doing. Adherence to this practice is however extremely important. The result of thinning (reducing the number of stems) encourages a strong crown, a well-developed root system and it establishes a proportional balance of upper growth to growth below the soil. Allowing an overabundance of flowers in the early years is detrimental to the long-term health of the delphinium. For thinning then, the rule in the first year is to allow no more than 2 stems or the plant should not be allowed to have more stems than the age of the plant plus one for its first five years. After five years, limit growth to 6-7 stems.
In the border they should be placed at the rear and other plants should be planted to cover the foliage after flowering. Heights of these delphiniums can range from 3 to 6 feet. Unfortunately, delphinium raised from seed will not always come true so odd happenings may occur with height and color.
That’s part of the fun!