Dahlia 'Cactus Mixed' Seeds

Dahlia variabilis (Cactus Group) is a robust Half-Hardy Perennial (H2), typically grown as a high-performance annual from seed. What sets this group apart is the unique petal formation; each petal is rolled backwards into a tight "quill," resulting in an architectural, starburst appearance that catches the summer light spectacularly.

Superior Weather Resistance: Due to their spiky, quilled petals, Cactus Dahlias possess superior rain resistance compared to heavy "decorative" or "dinnerplate" varieties. Rainwater runs freely off the petals rather than becoming trapped within the flower head, meaning the blooms are far less likely to become soggy or rot during a wet British summer.

Building a Tuber Collection: While these Dahlias flower reliably in their first year from seed, they will still develop energy-storing tubers underground by autumn. If you find a particular colour or form you love, the tubers can be lifted after the first frost and stored in a cool, dry, frost-free environment to be replanted the following spring.

Dahlias are fast-growing and incredibly rewarding, typically reaching maturity and blooming just 12-14 weeks after sowing.

How to Sow:
Sow indoors from February to April. Sow the seeds onto the surface of moist seed compost and cover with a fine layer of vermiculite. Maintain a constant temperature of 20-25°C for rapid germination, which usually occurs within 7-14 days. When seedlings are large enough to handle, prick them out into individual pots, handling them only by the leaves to avoid bruising the delicate stems.

Where to Plant:
Only plant out in late May or June once all risk of frost has passed. They demand full sun and deep, rich, fertile soil. Dahlias are hungry plants; we recommend digging in plenty of organic matter or feeding weekly with a potash-rich fertilizer once the flower buds begin to form. Space plants 50cm apart to allow for vigorous growth.

Ongoing Care:
To ensure a relentless display, pinching and deadheading are vital. Pinch out the top growing tip once the plant has developed 3-4 pairs of leaves to encourage a bushy, multi-stemmed habit. Throughout the season, regularly remove faded flower heads to prevent the plant from setting seed, ensuring a continuous supply of fresh blooms until the first autumn frosts.

Cactus Dahlias have bold, intense colours and heavy heads, so they look spectacularly balanced when paired with airier companions from our range:

• ☁️ Cosmos 'Purity': The Bright Backdrop. The clean white silk-faces and fine, ferny foliage of 'Purity' create a soft, floating background that allows the spiky, intense tropical colours of the 'Cactus Mixed' Dahlias to truly stand out. This is a quintessential florist-style pairing.
• 🕊️ Ammi majus: The Texture Match. Mixing the architectural spikes of the Dahlia with the soft, frothy white lace of Ammi majus creates a professional-looking, tiered border. The airy lace fills the gaps between the heavy dahlia heads, creating a sophisticated and balanced late-summer display.

Sow indoors in spring for a riot of starburst blooms from mid-summer through to the very first autumn frosts.