The bold beauty of Delphiniums at the Abby Garden

With each year, I continue to be amazed at the evolution of the design of the flower borders at the Abby Aldrich Rockefeller Garden. One of my favorite perennials that provides an architectural detail and stunning colors to the borders is delphinium.  

Pagan Purples delphiniums on the west side of the garden 

Delphiniums have long been a staple in traditional and formal perennial gardens and have had a presence in the Abby Garden design for decades. As they mature, they make their presence known as their flower spikes called racemes, shoot up to five or even seven feet. Their height is intended to draw your eye in and break up the long 180-foot flower beds. Their rich flower colors of blue-violet, white, pale lavender-blue, and pink give the borders a burst of color early in season.  

Delphiniums demand a cool-to-temperate climate to perform at their best. Our summer climate on the southern tip of Mount Desert Island, with those foggy mornings and cool nights, makes us well situated for delphiniums to thrive. They also prefer well-drained loamy soil, with a pH of 6.5 to 7.0 and should be watered regularly, especially during dry periods. 

Morning Lights at the south end of the garden 

For us, delphiniums start growing in early May. The new growth will begin to emerge from the crown of the delphinium and the base of the previous year’s flower stalks. The previous year’s growth looks like hollow, decaying stumps. It is hard to imagine that something so stunning can transform out of the stumps. When this new growth begins to appear, it is highly susceptible to widespread slug and snail damage, which causes small holes and tears in the foliage, affecting the aesthetics of the garden display. We begin laying down organic slug and snail bait every month to try and combat the population early on. We also handpick the snails and slugs and dispose of them when we observe them in the early growth of spring.  

Delphinium support is time consuming, but so worth it, and part of the annual maintenance for these plants. The goal is a formal upright look, but it is also crucial to protecting the tall, heavy flower stalks from breaking during high winds and rain. We start the support by encircling the plant with three-foot-tall pieces of pea brush to ensure all the flower stalks of the plant are growing straight. It is imperative that the flower stalks are not lying on the ground or growing crooked for our formal display. The pieces of pea brush are left supporting the delphinium until the flower stalks are tall enough to stake individually. This is done just before the flowers open the first week of July.  

In addition to the pea brush, flower stalks are supported with bamboo stakes in such a way that the stakes disappear when the flowers are in bloom. Curated over generations by garden staff, a paint color has been formulated to match the mid-green color of the flower stalks of the plant. When the bamboo stakes are painted, they are almost invisible to most garden guests.  

We insert the painted bamboo stakes tightly against the flower stalk and marry the stake to the plant using thin cotton twine tied in one-inch increments graduating up the flower stalk, stopping just shy of the budding top. As the flowers open, the bamboo stake is well camouflaged within the plant. Once the delphiniums start to flower, their blooms will continue for approximately two to three weeks, carrying the garden into early August. 

We have several different cultivars of New Millennium Series of delphinium planted on both east and west sides of the border garden—Pagan Purples, Cobalt Dreams, Morning Lights, Blue Lace, and Sunny Skies. These hybrids have been bred to be hardier, more disease-resistant, temperature tolerant, and are available in a more expanded blossom spectrum than previous varieties. 

Cobalt Dreams

Cobalt Dreams is the earliest to bloom in the borders each season. I love the true-blue cobalt color this delphinium brings to our borders by July 4th, before we greet the first visitors to the garden. Slightly shorter than some of our other delphiniums, it stands around five feet tall when mature. Cobalt Dreams is true to its name with bright blue cobalt-colored florets and a contrasting white eye. The eye, that cluster of short flower petals in the center of the flower, can also be called a bee. I think the rich blue hues pair well with the bright oranges, yellows, and reds on the garden’s east side, the hot side of the garden.  

Erin with Delphinium Pagan Purples 

Pagan Purples towers at over seven feet when mature and repeats throughout the garden borders. Its flowers come with spectacular double-bloom florets in a deep blue purple with unique brown bees. Pagan Purples is our most widely used cultivar in the garden design. It stands the tallest among the other cultivars and has proven to be more long-lived through our winters than some of the others, and its color is unmatched. Between its height and beautifully colored blooms, Pagan Purples adds a dramatic presence to the mid-July garden.  

Morning Lights is distinctly lighter in color than many other varieties, with friendly mauve to light blue double florets and complimentary white bees. I enjoy seeing the color of the blooms change as they mature. They are lighter when they first open, beginning at the bottom of the flower spike. As the rest of the flower spike opens, the blooms darken a bit, and a migrating mauve color shines through. Morning Lights are planted on the cool-colored west side of the border garden, where they nicely complement the palette of pale yellows, pinks, blues, and light purple flowers.  

Blossoms of Morning Lights

In addition to the spectacular show the delphiniums bring to the summer borders, they are also a hit for the garden’s many pollinators. They draw in an impressive number of bees by offering a stable landing pad. Our gardeners often find bumblebees sleeping in the delphinium blooms in the early morning hours while removing spent flowers and dead leaves from the plants in the flower beds. Butterflies and hummingbirds capture the nectar and there is a special magic when hummingbirds dance at your eye level, close enough to touch or feel the vibrations of their wings.

The delphinium plants found in these borders are grown from seed by the Preserve’s plant propagation team at McAlpin Farm. This allows us to transplant in older two- or three-year-old plants as replacements. Older plants are ideal replacements since it can take them three years to perform at their mature size. Delphiniums do not reliably over-winter for us. They are particularly susceptible to a wet and warm winter, when we may lose some to rot. This is also common when there isn’t a heavy snowpack to insulate them during the coldest parts of winter.

Delphiniums depend on a well-balanced fertilizer of nitrogen, phosphorus, and potassium to thrive throughout the season. Nitrogen promotes leafy growth, lush foliage, and is crucial to overall plant growth and vigor. Phosphorus encourages root development and flowering, ensuring the plants have strong root systems and vibrant blooms. Potassium helps with disease resistance and enhances flower blooms. We fertilize our delphiniums with a slow-release organic granular fertilizer once in May when their new growth begins to emerge from the ground, and again in mid- to late July to support continued growth and sometimes even a second flush of blooms in mid- to late August.

It is undeniable the way that delphiniums capture your attention when you walk into the Abby Garden in July. They are frequently commented on by our guests, which is understandable given their tall, vibrant blooms. They put on quite a spectacular show and, along with many other beautiful flowers, transform the Abby Garden into a living work of art for a few short weeks. 

Story and photographs by Erin Paxton, Garden Manager, Abby Aldrich Rockefeller Garden 

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