Delphinium is a genus of about 300 species of annual and perennial flowering plants in the family Ranunculaceae, native throughout the Northern Hemisphere and also on the high mountains of tropical Africa. The genus was erected by Carl Linnaeus. All members of the genus Delphinium are toxic to humans and livestock. The common name larkspur is shared between perennial Delphinium species and annual species of the genus Consolida.
Perennial in most areas, though some are treated as annuals or biennials. They are known for their tall, erect stems topped with spikes of colorful flowers. Ranges from dwarf varieties that are 1-2 feet tall to the taller garden varieties that can reach up to 8 feet. The flowers are typically showy, with five petal-like sepals, one of which forms a spur (hence the name “larkspur”). Colors vary widely including various shades of blue, purple, white, pink, and even some with black or nearly black blooms. Flowers are arranged in clusters along the spike, which can be single or double flowered. The leaves are deeply lobed or divided, often palmate, and can be quite lush, providing a good backdrop for the flowers.
Delphinium Plants
Delphinium elatum (Pacific Giants)
- Characteristics: This tall variety is known for its striking spires of blue, purple, and white flowers. It’s part of the Pacific Hybrid group.
- Size: Grows 4-6 feet tall.
- Bloom Time: Early to mid-summer.
- Foliage: Deeply lobed, green leaves.
- Ideal Conditions: Prefers full sun and rich, well-drained soil with consistent moisture.
Delphinium belladonna (Belladonna Group)
- Characteristics: A more compact type with airy, loosely packed blooms that are often sky-blue or light blue.
- Size: Typically 2-4 feet tall.
- Bloom Time: Early summer with potential for rebloom in fall.
- Foliage: Finely divided, dark green leaves.
- Ideal Conditions: Thrives in full sun and moist, well-draining soil.
Delphinium grandiflorum (Chinese Delphinium)
- Characteristics: Shorter than many other varieties, it features large, single flowers in shades of blue and purple.
- Size: Grows 1-2 feet tall.
- Bloom Time: Late spring to early summer.
- Foliage: Delicate, fern-like leaves.
- Ideal Conditions: Prefers full sun and light, well-drained soil.
Delphinium ‘Black Knight’
- Characteristics: Part of the Pacific Giants series, known for its deep, midnight purple flowers with a dark center (bee).
- Size: Reaches 4-6 feet in height.
- Bloom Time: Early to mid-summer.
- Foliage: Deep green, deeply lobed leaves.
- Ideal Conditions: Full sun and fertile, moist soil.
Delphinium ‘King Arthur’
- Characteristics: Another Pacific Giant, featuring vibrant purple flowers with a white bee (center).
- Size: Grows to 4-6 feet tall.
- Bloom Time: Early summer.
- Foliage: Glossy, green leaves.
- Ideal Conditions: Full sun and well-drained, nutrient-rich soil.
Delphinium ‘Galahad’
- Characteristics: A tall, striking variety with pure white flowers and a strong, elegant appearance.
- Size: Reaches 4-6 feet in height.
- Bloom Time: Early to mid-summer.
- Foliage: Large, green leaves.
- Ideal Conditions: Requires full sun and moist, fertile soil.
Delphinium ‘Blue Bird’
- Characteristics: Features bright sky-blue flowers with a contrasting white or black bee.
- Size: Grows up to 4-6 feet tall.
- Bloom Time: Early summer.
- Foliage: Green, deeply lobed leaves.
- Ideal Conditions: Prefers full sun and well-drained, rich soil.
Delphinium ‘Magic Fountains’
- Characteristics: A more compact hybrid, perfect for smaller gardens or containers, available in shades of blue, lavender, and white.
- Size: Grows 2-3 feet tall.
- Bloom Time: Early summer.
- Foliage: Dark green, lobed leaves.
- Ideal Conditions: Thrives in full sun and fertile, moist soil.
Delphinium ‘Summer Skies’
- Characteristics: A light, sky-blue variety with a white center, part of the Pacific Giant group.
- Size: Can grow up to 4-6 feet.
- Bloom Time: Early to mid-summer.
- Foliage: Deep green leaves.
- Ideal Conditions: Full sun and moist, rich soil.
Delphinium ‘Astolat’
- Characteristics: Offers a mix of pinkish-purple flowers with a white bee, creating a soft, romantic effect.
- Size: Grows to 4-5 feet tall.
- Bloom Time: Early summer.
- Foliage: Green, lobed leaves.
- Ideal Conditions: Full sun and nutrient-dense, well-drained soil.
Delphinium ‘Percival’
- Characteristics: A beautiful white variety with a creamy, slightly tinted center, adding elegance to any garden.
- Size: Reaches about 4-5 feet tall.
- Bloom Time: Early to mid-summer.
- Foliage: Deep green leaves.
- Ideal Conditions: Prefers full sun and consistently moist, rich soil.
Delphinium ‘Guardian Blue’
- Characteristics: Known for its strong, dark blue flowers that are more resistant to heat compared to some other types.
- Size: Grows 3-4 feet tall.
- Bloom Time: Early to mid-summer.
- Foliage: Dark green leaves with a lobed shape.
- Ideal Conditions: Thrives in full sun and well-drained, fertile soil.
Delphinium ‘Excalibur’
- Characteristics: A compact variety with sturdy stems and bright, dense flower spikes in shades of blue, white, and lavender.
- Size: Typically grows 2-3 feet tall.
- Bloom Time: Early to mid-summer.
- Foliage: Green, lobed leaves.
- Ideal Conditions: Prefers full sun and fertile, well-drained soil.
Delphinium ‘Centurion Sky Blue’
- Characteristics: Features striking sky-blue flowers with a white or dark center.
- Size: Reaches up to 4-5 feet tall.
- Bloom Time: Early summer.
- Foliage: Deep green, lobed leaves.
- Ideal Conditions: Thrives in full sun and well-draining soil.
Delphinium ‘Blue Lace’
- Characteristics: Known for its soft, powder-blue petals and a contrasting white center, giving it a delicate appearance.
- Size: Grows to about 4-6 feet tall.
- Bloom Time: Early summer.
- Foliage: Dark green, deeply lobed leaves.
- Ideal Conditions: Requires full sun and rich, well-drained soil.
Delphinium ‘Cobalt Dreams’
- Characteristics: Offers vibrant, cobalt-blue flowers that are particularly eye-catching in garden settings.
- Size: Reaches 4-6 feet in height.
- Bloom Time: Early to mid-summer.
- Foliage: Green, lobed leaves.
- Ideal Conditions: Prefers full sun and nutrient-rich, moist soil.
Delphinium ‘White King’
- Characteristics: Features pure white blooms with a subtle cream or light green center.
- Size: Typically grows 4-5 feet tall.
- Bloom Time: Early summer.
- Foliage: Dark green, deeply cut leaves.
- Ideal Conditions: Thrives in full sun and well-draining soil.
Delphinium ‘Millennium Delphiniums’
- Characteristics: Part of a newer breed known for strong stems and vibrant shades of blue, purple, and pink.
- Size: Reaches 3-5 feet in height.
- Bloom Time: Early to mid-summer.
- Foliage: Deep green, attractive leaves.
- Ideal Conditions: Prefers full sun and rich, well-draining soil.
Delphinium ‘Pink Sensation’
- Characteristics: A unique pink variety with light, soft petals and a white or dark bee.
- Size: Grows to about 3-4 feet tall.
- Bloom Time: Early summer.
- Foliage: Green, lobed leaves.
- Ideal Conditions: Full sun and fertile, moist soil.
Delphinium ‘Dark Blue with Bee’
- Characteristics: Offers deep blue flowers with a distinctive white or black bee in the center.
- Size: Can grow 3-5 feet tall.
- Bloom Time: Mid-summer.
- Foliage: Dark green leaves.
- Ideal Conditions: Prefers full sun and rich, well-drained soil.
Delphinium ‘Princess Caroline’
- Characteristics: Features light lavender-pink flowers with a white bee, perfect for adding a romantic touch to gardens.
- Size: Reaches 3-4 feet tall.
- Bloom Time: Early to mid-summer.
- Foliage: Deep green, lobed leaves.
- Ideal Conditions: Thrives in full sun and nutrient-rich soil.
Delphinium ‘Guardian Lavender’
- Characteristics: This sturdy type has light lavender blooms with a white center, great for cutting gardens.
- Size: Grows up to 3-4 feet tall.
- Bloom Time: Early to mid-summer.
- Foliage: Green leaves with a lobed pattern.
- Ideal Conditions: Full sun and well-draining soil are essential.
Delphinium ‘Pagan Purples’
- Characteristics: Rich, deep purple blooms with contrasting white or black centers.
- Size: Reaches about 5-6 feet tall.
- Bloom Time: Early to mid-summer.
- Foliage: Deeply lobed, dark green leaves.
- Ideal Conditions: Full sun and well-drained, fertile soil.
Delphinium ‘Moonlight Blues’
- Characteristics: Offers pale blue blooms with a soft, ethereal appearance and a white bee.
- Size: Grows 4-5 feet tall.
- Bloom Time: Early summer.
- Foliage: Dark green, lobed leaves.
- Ideal Conditions: Prefers full sun and consistently moist, fertile soil.
Cultivation
- Light: Prefers full sun but can tolerate light shade, especially in hotter climates.
- Soil: Needs well-drained, fertile soil enriched with organic matter. They thrive in slightly alkaline to neutral soil.
- Water: Requires regular watering to keep the soil consistently moist but not soggy. Mulching can help retain soil moisture.
- Temperature: They do best in cooler climates; heat can be detrimental, especially in the peak of summer.
- Support: Taller varieties often require staking to prevent the stems from breaking under the weight of the flowers or due to wind.
Care Tips
- Fertilization: Feed with a high-potassium fertilizer to promote blooms, especially before and during the flowering period.
- Pruning/Deadheading: Deadheading spent flowers can encourage a second bloom later in the season. After flowering, cutting back can promote bushier growth or a late season bloom.
- Pest and Disease: Watch for slugs, snails, aphids, and powdery mildew. Good air circulation, avoiding overhead watering, and proper spacing can mitigate many issues.