Black Knight Blue Throatwort

Black Knight Blue Throatwort (Trachelium caeruleum 'Black Knight')

Black Knight Blue Throatwort brings rich, dark blue-purple flower clusters that make summer containers and sunny borders feel deeper and more finished. The rounded blooms sit above clean green foliage, giving you a polished look that works in both modern and cottage-style plantings. It flowers for a long stretch, so you get steady color when many annuals start to look tired. If you want a reliable cut flower look in the garden, this plant delivers strong stems and long-lasting bloom.

Distinctive Features

This plant produces dense, domed umbels of small, dark blue-purple flowers that read as a bold mass of color from a distance and detailed texture up close. Bloom typically runs from early summer into fall, especially with regular trimming of spent stems. The habit is upright and well-branched, creating a full clump that holds its shape in beds and larger containers. Mature size is commonly about 18 to 30 inches tall and 12 to 18 inches wide.

Growing Conditions

• Sun: Full sun to part shade, with some afternoon shade helpful in hotter climates.
• Soil: Moderately fertile, well-drained soil that holds some moisture but does not stay soggy.
• Water: Moderate, keep evenly moist during establishment, then water when the top layer begins to dry.
• Zones: USDA Zones 9 to 11, and grown as an annual in colder regions.
• Notable Traits: Lightly fragrant blooms, strong stems, and excellent performance as a cut flower.

Ideal Uses

• Focal Point: Plant a tight group in a border or a large pot as a focal point where the dark blue-purple bloom can anchor the color palette.
• Containers: Use in patio pots to add height and a florist-style flower form that stays attractive for weeks.
• Cut Flower Gardens: Grow for sturdy stems that hold well in arrangements and add rich color as a bouquet filler.
• Mixed Borders: Combine with lighter flowers and silvery foliage to create contrast and a more layered, designed look.

Low Maintenance Care

• Deadheading: Trim spent flower stems to encourage continued bloom and keep the plant looking fresh.
• Watering: Avoid drought stress in heat, since consistent moisture supports stronger flowering and fuller growth.
• Feeding: Feed lightly through the season, especially in containers, to support continuous bloom.
• End of Season: In cold regions, treat as seasonal, and in warm zones cut back after flowering to refresh growth.

Why Choose Black Knight Blue Throatwort?

• Deep Color: Dark blue-purple flower clusters add depth and contrast that elevates summer plantings.
• Long Bloom: Flowers from early summer into fall with simple trimming of spent stems.
• Cut Flower Value: Provides strong, long-lasting stems that bring a florist finish to arrangements.
• Easy Structure: Upright habit and a 18 to 30 inch size range add height without overwhelming nearby plants.

Black Knight Blue Throatwort is a smart way to add saturated color and clean structure through the heart of the growing season. Pair it with whites, yellows, and soft pinks for contrast, or use it to deepen a cool-toned palette with blues and purples. Keep it in sun with good drainage and steady moisture, and it will keep producing fresh bloom for months. If you want one plant that looks arranged even before you cut a stem, this one fits.