Delphinium Highlander Bolero is a perennial known for its vertical presence and vibrant color. This cultivar is popular for adding height and elegance to garden designs.
Delphinium Highlander Bolero: Unique Characteristics
Delphinium ‘Highlander Bolero’ features distinctive double blooms, typically deep purple or purplish-blue with white centers. Each flower is densely packed and frilled, forming a lush, rounded head on sturdy stems.
‘Highlander Bolero’ grows 30 to 40 inches (75-100 cm) tall, sometimes reaching 4 feet with flower spikes, and spreads 16 to 20 inches (40-50 cm) wide. It blooms for weeks from early to mid-summer. Its sterile blossoms last longer than other delphinium varieties. This plant attracts bees, butterflies, and hummingbirds, and is generally ignored by deer and rabbits.
Planting Delphinium Highlander Bolero
Site Selection and Soil Preparation
Delphinium Highlander Bolero thrives in full sun and needs a location sheltered from strong winds to protect its tall flower spikes. It requires fertile, well-draining soil that is consistently moist. An ideal soil pH is neutral to slightly alkaline (5.8 to 7.0).
Prepare the soil by enriching it with compost or well-rotted manure to enhance fertility and drainage. If soil is acidic, add lime to adjust the pH. For heavy or clay soils, add grit to improve drainage, as delphiniums struggle in wet winter conditions. Space multiple delphiniums 12 to 20 inches (30-50 cm) apart for air circulation.
Planting Steps
When planting Delphinium Highlander Bolero from a nursery container or bare root, dig a hole deep enough for the root ball. Set the plant at the same soil level as its original pot, ensuring the crown is not buried too deep. Backfill with prepared soil, lightly firming it around the base to remove air pockets.
After planting, water thoroughly. Apply mulch around the base to retain soil moisture and keep roots cool, but avoid piling it directly against stems to prevent rot. For bare roots, ensure the pointed side or sprout side faces upward before covering with soil.
Ongoing Care for Delphinium Highlander Bolero
Watering
Delphinium Highlander Bolero prefers consistently moist soil. Water deeply once a week, especially during dry periods. Water at the base of the plant, keeping foliage dry, to prevent fungal diseases. Ensure soil is moist but not waterlogged to avoid root rot. Newly planted delphiniums may require more frequent watering until established.
Fertilizing
Delphiniums are heavy feeders and benefit from regular fertilization. Apply a balanced, slow-release fertilizer or well-composted organic material in early spring. During active growth and flowering, apply a balanced liquid feed every two to three weeks. Avoid excessive nitrogen, which promotes foliage over flowers. Yellowing foliage or stunted growth indicates a need for more fertilizer.
Staking and Support
Due to their height and tall flower spikes, Delphinium Highlander Bolero often requires staking to prevent stems from flopping or breaking. Install supports in spring before plants reach full height, when they are about 12 inches tall.
Methods include using three canes around each plant, forming a cage with twine as the plant grows. Single bamboo canes can also be used, tying the plant to the support with natural twine in a figure-eight pattern, from the base to just below the flower head. When inserting stakes, avoid damaging the root system.
Deadheading and Pruning
Deadheading spent flower spikes encourages continuous blooming and redirects energy into producing more flowers. After the first flush of blooms, cut spent spikes back to small, flowering side shoots. For a second flush in late summer or early autumn, cut flower stalks almost to the ground, leaving basal foliage intact.
In late fall, after flowering and foliage wither, cut the plant back to 2-5 cm (1-2 inches) from the ground. This pruning prevents fungal diseases and prepares the plant for winter. Wear gardening gloves when handling delphiniums, as all parts are toxic if ingested.
Troubleshooting Common Issues
Powdery mildew, a common fungal disease, appears as white or grayish patches on leaves and stems. It thrives in humid conditions and is prevented by good air circulation, avoiding overcrowding, and watering at the plant’s base to keep foliage dry. If it appears, remove infected leaves and apply a fungicide.
Slugs and snails are common pests that cause damage, leaving ragged holes and silvery trails. Young plants are vulnerable. Deter them with horticultural grit around the base or slug baits. Aphids suck plant sap, leading to curled or distorted leaves. Manage them with insecticidal soaps, neem oil, or by encouraging natural predators.