Cosmos Rubenza Seeds

Cosmos Rubenza – Cosmos bipinnatus

A richly hued annual with velvety ruby-red blooms that fade to antique rose — ideal for cutting gardens, pollinator borders, and romantic summer displays.

Cosmos Rubenza is a half-hardy annual known for its dramatic colour shift: deep wine-red petals open boldly and gradually soften to dusky rose, creating a painterly effect across the season. The semi-double blooms sit atop airy, fern-like foliage and sway gracefully in the breeze. Loved by bees and butterflies, this Fleuroselect award-winning variety brings height, movement, and vintage charm to borders, wildflower plantings, and cottage-style schemes. Long stems make it a standout for cut flower arrangements. Easy to grow and drought-tolerant once established.

 

Seed Qty: Approx. 50

 

Sow: February – April (indoors) or May (direct)

Germination: 7 – 14 days at 18–21°C

Soil: Well-drained; loam, chalk, or sandy; neutral to slightly alkaline

Height: 60 – 90 cm

Flowers: June – October

Good Companions: Ammi majus, calendula, cosmos ‘Purity’

Avoid Pairing With: Shade-loving or moisture-demanding plants

 

Growing Notes

Sow indoors from February to April in trays or modules, covering seeds lightly with 5 mm of compost. Maintain 18–21°C and keep moist until germination (7–14 days). Transplant seedlings when large enough to handle, spacing 30–40 cm apart. Harden off before planting out after the last frost. Alternatively, direct sow outdoors in May once soil has warmed. Deadhead regularly to extend flowering and harvest stems when buds are just opening for the vase.