Giant Knapweed Seeds

Giant Knapweed Seeds – Irish Plants Direct

 

A dramatic and long lived perennial with large, lemon yellow, thistle like flower heads up to 10 cm across, emerging from papery brown buds.

 

They forms sturdy clumps of lance shaped green foliage and blooms from early to mid summer. Its bold structure and vibrant colour make it ideal for borders, wildflower meadows, and naturalistic planting.

 

This hardy perennial thrives in full sun and moist, well drained soil. It attracts bees, butterflies, and other pollinators and is excellent for cut flowers and dried arrangements. 

 

Seed Qty Approx 1gram

 

Sow February to May indoors or direct outdoors from March

Germination 14 to 28 days at 18 to 22°C

Soil and Position Moist but well-drained loamy, chalky, or sandy soil in full sun

Height/Spread 100 to 150 cm tall, 40 to 60 cm spread

Flowering June to August (second year)

 

Sowing Instructions

 

Sow seeds 3 mm deep in trays or modules and keep at 18 to 22°C until germination. Transplant into individual pots when large enough to handle. Harden off and plant outdoors after the last frost. Space plants 40 to 50 cm apart. For best results, sow early and allow plants to establish before flowering the following year.

 

Grow and Maintenance

 

Water regularly during dry spells and mulch in spring. Deadhead to prolong flowering or leave seed heads for winter interest. Divide clumps every 3 to 4 years in spring or autumn. Suitable for borders, meadows, and pollinator planting. May self-seed in open ground.

 

Uses and Benefits

 

Large yellow thistle like blooms

Attracts bees, butterflies, and hoverflies

Hardy perennial with bold structure

Perfect for borders, wildflower meadows, and cutting

Excellent for dried arrangements and naturalising

 

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