Cosmos 'Sensation Dazzler' Seeds

Cosmos bipinnatus 'Sensation Dazzler' is a robust Half-Hardy Annual (H2). Native to the sun-baked highlands of Mexico, it is biologically hardwired to thrive in full sun and surprisingly lean, dry soil. It belongs to the legendary "Sensation" series, bred specifically for colossus bloom size and strong, tall stems that are perfect for professional-grade cutting.

The "Starvation" Rule: One of the most critical aspects of Cosmos biology is its dislike of rich soil. If grown in manured ground or treated with high-nitrogen fertilizers, the plant will put all its energy into massive green foliage, often failing to produce any flowers at all. For the best floral display, plant 'Dazzler' in the poorest, leanest part of your garden and avoid feeding entirely.

Late-Season Biodiversity: As an RHS Plant for Pollinators, 'Sensation Dazzler' is a vital late-summer resource. Its simple, open-faced architecture provides a perfect landing platform for bees and butterflies. Because it continues to bloom prolifically until the first November frosts, it provides essential nectar at a time when most other garden resources have vanished.

Cosmos is one of the easiest and fastest plants to raise from seed, making it a perfect project for beginners or children.

How to Sow:
Sow indoors from March to May for early summer blooms, or direct sow outdoors in May or June once the soil has warmed. Sow seeds 5mm deep into moist seed compost. Germination is exceptionally rapid, typically occurring within 7-14 days at a constant temperature of 18-20°C. If sowing indoors, no specialized heat mat is required; a bright windowsill is perfect.

Where to Plant:
They demand full sun and thrive in poor, well-drained soil. They are the perfect solution for established borders that need a burst of vertical colour or for creating a seasonal screen to hide unsightly fences. Space plants 45cm apart to allow their airy, architectural habit to develop fully without overcrowding.

Ongoing Care:
To encourage a sturdy, multi-stemmed plant, pinching is essential. When seedlings reach 15-20cm tall, pinch out the top growing tip; this prevents the plant from becoming too "top-heavy" and toppling over in late summer storms. Consistent deadheading is also vital—the more you cut for the vase, the more the plant will reward you with fresh buds until the hard frosts of November.

The intense, electric carmine-crimson of 'Dazzler' looks spectacular when paired with fresh, zesty, or cooling partners from our range:

• 🍋 Larkspur 'Limelight Mix': The Zesty Clash. This is a bold, modern combination where the lime-green and creamy-white vertical spikes of the Larkspur provide an electric contrast to the deep red of 'Dazzler'. The lime-green tones make the crimson petals appear even more saturated, creating a professional-looking, high-energy border.
• ☁️ Ammi majus: The Classic Softener. For a more romantic aesthetic, plant 'Dazzler' alongside the pure white lacy umbels of Ammi majus. The white lace breaks up the mass of red, adding an airy "wild meadow" feel to the border that keeps the display feeling fresh and cooling during the peak of summer.

Sow indoors in spring or direct sow once the soil warms for an unstoppable harvest of vibrant crimson blooms from mid-summer until the autumn frosts.