Growing Guide: Delphiniums (Delphinium spp.)


Few flowers boast the majestic allure of the Delphinium. With their towering spires of blooms in an array of breathtaking hues, these regal beauties command attention wherever they're planted. Whether you're an experienced gardener or just dipping your toes into the world of perennial delights, delphiniums are sure to captivate your heart and elevate your garden to new heights.

Delightful Delphiniums: A Growing Guide

Meet the Delphiniums

Let's start with a formal introduction to these splendid blooms. Delphiniums, belonging to the genus Delphinium, are members of the buttercup family, Ranunculaceae. Their name is derived from the Greek word "delphis," meaning dolphin, owing to the shape of their buds, which supposedly resemble the playful marine mammals.

Varieties Galore

One of the joys of cultivating delphiniums is the sheer variety available to gardeners. From the majestic Pacific Giant hybrids to the more diminutive Belladonna group, there's a delphinium to suit every garden style and preference. Some popular cultivars include Delphinium 'Magic Fountain', 'Guardian', and 'Black Knight', each offering its own unique charm and character.

Planting Delphiniums

Now, let's roll up our sleeves and get down to the nitty-gritty of planting these enchanting blooms. Delphiniums thrive in rich, well-drained soil with a slightly alkaline pH. Choose a sunny spot in your garden with at least six hours of sunlight daily, although some afternoon shade in hotter climates can be beneficial.

When it comes to planting, ensure you dig a hole twice as wide as the root ball and amend the soil with compost or well-rotted manure to boost fertility. Gently place your delphinium in the hole, backfill with soil, and water thoroughly to settle the roots in place.

Caring for Delphiniums

While delphiniums may exude an air of aristocracy, they're surprisingly low-maintenance with proper care. Here are some tips to keep your delphiniums thriving:

  1. Watering: Delphiniums appreciate consistent moisture, especially during dry spells or when grown in containers. Water deeply, allowing the soil to dry slightly between waterings to prevent root rot.
  2. Support: Given their lofty stature, delphiniums may require staking to prevent toppling over in gusty winds or heavy rains. Install stakes or use discreet plant supports early in the growing season to provide ample support without detracting from their natural beauty.
  3. Fertilizing: Feed your delphiniums with a balanced fertilizer in spring as new growth emerges, and again after the first flush of blooms to encourage a second round of flowering. Avoid high-nitrogen fertilizers, as they can promote lush foliage at the expense of flowers.
  4. Deadheading: To prolong the flowering season and encourage repeat blooms, deadhead spent flowers regularly. Snip the flower stalks back to a set of healthy leaves to stimulate new growth and budding.

Pest and Disease Management

Like any garden plant, delphiniums aren't immune to pests and diseases, but with vigilance, you can keep these issues at bay. Watch out for common pests such as aphids, slugs, and snails, and take prompt action to mitigate their damage. Additionally, provide adequate air circulation around plants to prevent fungal diseases like powdery mildew, and avoid overhead watering, which can exacerbate these issues.

In the grand tapestry of the garden, delphiniums undoubtedly take center stage with their towering spires of blooms and vibrant hues. Whether you're seeking to add vertical interest to your borders or create a show-stopping focal point, these regal beauties won't disappoint. With proper siting, planting, and care, you can enjoy the splendor of delphiniums in your garden for years to come, weaving a tale of beauty and grace that unfolds with each passing season.

Frequently asked questions

Where is the best place to plant delphiniums? Delphiniums thrive in full sun or partial shade. Choose a location in your garden that receives at least six hours of sunlight daily for optimal growth and flowering.

Do delphiniums like sun or shade? Delphiniums prefer full sun to partial shade. While they appreciate ample sunlight, some afternoon shade in hotter climates can help protect them from scorching heat.

What is the best feed for delphiniums? A balanced fertilizer, such as a 10-10-10 formulation, applied in spring as new growth emerges and again after the first flush of blooms, can provide the necessary nutrients for healthy growth and flowering.

Do delphiniums need a trellis? While some taller varieties may benefit from staking or support to prevent them from toppling over in windy conditions, delphiniums generally do not require a trellis.

Do delphiniums spread? Delphiniums do not spread aggressively like some groundcover plants. They grow from a central crown and gradually expand over time, but they typically maintain a clumping growth habit.

Should I deadhead delphiniums? Yes, deadheading spent flowers regularly can prolong the flowering season and encourage repeat blooms. Snip the flower stalks back to a set of healthy leaves to stimulate new growth and budding.

Does delphinium multiply? Delphiniums can multiply through division, where you can separate the crown and roots of established plants to create new specimens. Additionally, some varieties may self-seed under favorable conditions.

Are delphiniums fast growing? Delphiniums are not considered fast-growing plants. They have a moderate growth rate, with their towering flower spikes gradually developing over the growing season.

Do delphiniums like acidic or alkaline soil? Delphiniums prefer rich, well-drained soil with a slightly alkaline pH. Amending the soil with organic matter can help improve fertility and drainage.

What to plant next to delphiniums? Complementary companions for delphiniums include other sun-loving perennials such as daylilies, salvia, catmint, and lavender, which can provide contrasting textures and colors while sharing similar growing conditions.

How long do delphiniums last? With proper care, delphiniums can live for several years, returning reliably each spring to grace your garden with their exquisite blooms.

Will delphinium self-seed? Some delphinium varieties may self-seed under favorable conditions, producing new plants from dropped seeds. However, not all cultivars exhibit this tendency, and deadheading spent flowers can help control self-seeding.

Are delphiniums poisonous to dogs? Yes, delphiniums are considered toxic to dogs if ingested. It's essential to keep pets away from these plants to prevent potential poisoning.

Are Larkspur and delphinium the same thing? Larkspur (Consolida spp.) and delphiniums (Delphinium spp.) belong to the same family, Ranunculaceae, and share similar characteristics, but they are distinct genera with some differences in growth habit and flower structure.

Are delphiniums perennials in Canada? Yes, delphiniums are perennials in Canada and can withstand the cold winters of the region, provided they receive adequate protection and care.

How do I keep slugs from eating my delphiniums? To deter slugs from feasting on your delphiniums, you can employ various methods such as applying slug repellents, setting up physical barriers like copper tape around plantings, or introducing natural predators like predatory ground beetles.

What are the benefits of delphiniums? Delphiniums not only add vertical interest and vibrant color to the garden but also attract pollinators like bees and butterflies with their nectar-rich flowers, contributing to overall biodiversity and ecosystem health.

How do you get rid of delphinium worms? Delphinium worms, the larvae of the western yellowstriped armyworm, can be controlled through handpicking, applying organic insecticides like Bacillus thuringiensis (Bt), or introducing natural predators such as parasitic wasps.

Can you grow Delphinium in pots? Yes, delphiniums can be grown in pots or containers, provided they receive adequate sunlight, moisture, and well-draining potting soil. Taller varieties may require staking or support to prevent them from toppling over in containers.

Are delphiniums poisonous to cats? Yes, delphiniums are toxic to cats if ingested. It's essential to keep cats away from these plants to prevent potential poisoning.

Is monkshood the same as Delphinium? No, monkshood (Aconitum spp.) and delphiniums (Delphinium spp.) are different genera belonging to the Ranunculaceae family. While they may share some similarities in appearance, they are distinct plants with different growth habits and toxicities.

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