Delphiniums, belonging to the genus Delphinium within the Ranunculaceae family, are celebrated for their striking vertical racemes of vibrant flowers. Their symbolism and popularity in American cut flower gardens are deeply intertwined with their unique botanical characteristics, which present both challenges and immense rewards for gardeners.
The most defining feature of the delphinium is its flower structure. The common name "larkspur" (often used interchangeably, though botanically distinct for annual species) originates from the shape of the nectar-secreting petal, known as the sepal, which forms a long spur resembling the hind claw of a lark. This intricate morphology contributes to its symbolic meanings. The genus name Delphinium itself comes from the Greek "delphis," meaning dolphin, alluding to the bud's shape. Historically, the flower has symbolized a wide range of sentiments, from heavenly aspiration and protection due to its sky-blue hues to lightness and levity because of its airy, towering form. In the language of flowers, it can also represent an open heart and ardent attachment, making it a powerful communicator in floral arrangements.
For delphiniums to thrive as a cut flower crop in US gardens, specific horticultural needs must be met. They are classified as herbaceous perennials, typically hardy in USDA zones 3-7, though they are often grown as annuals or short-lived perennials in warmer climates. They demand full sun exposure for strong stem development and intense flower coloration. Well-drained, fertile, and consistently moist soil with a neutral to slightly alkaline pH is crucial. Their tall flower spikes, which can reach heights of 6 feet or more, are highly susceptible to wind and heavy rain damage, necessitating staking for support. These requirements make them a high-maintenance but high-value crop for dedicated gardeners.
From a cut flower production standpoint, delphiniums are unparalleled for their role as a "line flower" in floral design. Their towering, densely-packed flower spikes provide essential vertical structure and dramatic height to arrangements. The color range, especially the iconic deep blues, light blues, and purples, is difficult to find in other cut flowers, making them highly sought after. White and pink cultivars offer additional versatility. To maximize production, gardeners practice successive sowing and diligent deadheading to encourage a second, though often smaller, flush of blooms later in the season. The primary challenge is their relatively short vase life of 5-7 days, which is managed by proper harvesting (when the bottom third of florets are open) and immediate hydration in a floral preservative solution.
The cultivation of delphiniums in the US has been greatly advanced by the development of specific series and cultivars bred for garden performance. The Pacific Giant Hybrids are a classic choice, known for their robust spikes and wide color range. The Magic Fountains series offers a more compact plant, better suited for windy sites without sacrificing flower quality. For the highest quality cut flowers, the New Millennium Series from New Zealand is renowned for its exceptionally strong stems, dense flower spikes, and improved disease resistance, representing a significant botanical advancement for commercial and serious amateur growers.
