Trachelium caeruleum White Knight - seeds

Trachelium caeruleum 'White Knight' is a variety of Trachelium with white flowers, originally selected for cut flowers. It is appreciated for its long flowering period with very uniform umbels, which open up to reveal pure white flowers. This perennial relative of bellflowers can flower in the year of sowing in Mediterranean climates, making it suitable for use as an annual in less favourable climates. Beautiful in a vase, as well as in the garden, its inflorescences are highly attractive to butterflies and pollinating insects. Planted between stones in a rock garden or wall, or scattered throughout flower beds, it creates clouds of charming flowers. It can also be grown in pots. Once well established in the ground, Trachelium caeruleum can withstand dry summers.

Trachelium caeruleum 'White Knight' belongs to the family of campanulas. It is a horticultural selection derived from the blue Trachelium, distinguished by its white flowers. This cultivar usually blooms a week after 'Black Knight'. The original species, with blue flowers, is native to Southern Europe and North Africa. Mostly grown as an annual, its root system can withstand temperatures down to -10/-12 °C (14/10.4°F) in dry soil. The foliage may partially persist in mild winters, otherwise, the stems die and regenerate in the following spring. It is particularly vulnerable to cold and wet conditions.

Trachelium caeruleum forms a clump of angular, abundantly leafy stems that branch out and turn woody at the base over time. The plant reaches a height of approximately 50 cm (20in) and a width of 40 cm (16in), depending on growing conditions. The lanceolate leaves have serrated margins. In the 'White Knight' cultivar, both the stems and leaves are glossy medium green. Flowering begins in May-June in the south and June-July further north. If the soil remains slightly moist and spent flowers are regularly removed, the plant will continue to bloom continuously until October. In very dry Mediterranean regions, flowering diminishes in July-August and resumes with the return of rain. The 10-15 cm (4-6in) wide inflorescences are composed of numerous tiny tubular flowers with spreading 5-lobed corollas. The flowers emit a sweet vanilla fragrance and are nectar-rich. After pollination by insects, small pear-shaped fruits containing very fine seeds are formed, which self-sow in dry stone walls or rocky soils. Plants grown from seeds may not necessarily be identical to the parent plant.

Trachelium caeruleum 'White Knight' will be wonderful in perennial borders, rock gardens, in walls, wild gardens, or in pots. This plant softens heavy floral displays and complements medium-sized grasses and asters perfectly. It can be paired with Alstroemerias, Chinese peonies, and old roses, both in the garden and in vases. In a dry Mediterranean garden, let it self-sow wherever it pleases, as it will flower even in shady areas, alongside Ivy-leaved Toadflax (Cymbalaria muralis) or wall rue Asplenium ceterach. Try growing some of these plants in large pots that you can store in a greenhouse or orangery, they will thrive and create a splendid effect!

Cut flower tip: pick the flowers when they are 75% open, trim the stems, and quickly place them in water. They will last for 10 to 14 days.