Some of the most spectacular dahlias are cactus and semi-cactus types. With their spiky blooms, their lineage can be traced back to a single surviving plant grown from a crate of tubers imported into the Netherlands in 1872.
Cactus and semi-cactus dahlias are some of the most eye-catching dahlias you can grow. Their star-like form means they stand up well to inclement weather, because they’re less prone to being weighed down by heavy rain than other dahlia types. They also need less staking than other varieties, which tend to have dense, heavy heads of petals. They make excellent cut flowers.
Care for cactus and semi-cactus dahlias as you would other types of dahlia: water well until established and in dry weather, pinch out the growing tip when the plant has reached 20cm in height, and stake taller varieties. Then, once in flower, feed fortnightly with a high potash feed, such as tomato feed, to keep the flowers coming. All dahlias are perennials so will come back year after year. However, in colder regions, you will need to lift your dahlia tubers and store them undercover, to protect them from frost.
Bear in mind that cactus and semi-cactus dahlias are not visited by bees or other pollinators, as the central part of the flowers are not accessible. If you want to grow dahlias for bees, choose single-flowered dahlias.
The difference between cactus and semi-cactus dahlias is in the flower:
- Cactus dahlias have fully double blooms, with very narrow petals from the tip to the base, that often curve inwards. They range in size from miniature to giant
- Semi-cactus dahlias have fully double, fluffy-looking flowers. The petals have a broader base at the bottom than cactus dahlias and are rolled in for about half of their length
Dahlia ‘Kenora Challenger’
Dahlia ‘Kenora Challenger’ is a tall-growing, semi-cactus dahlia, with dazzling bright white spiky blooms.
Height x Spread: 1.2m x 30cm
- How to grow Dahlia ‘Kenora Challenger’
- Buy Dahlia ‘Kenora Challenger’ from HW Hyde
Dahlia ‘Reputation’
This large-flowered cactus dahlia bears huge, bright magenta-pink blooms up to to 17cm across.
H x S: 1.2m x 40cm
- How to grow Dahlia ‘Reputation’
Dahlia ‘Trelyn Kiwi’
A compact cactus dahlia, ‘Trelyn Kiwi’ has pink-white blooms with a yellow central flush. Ideal for growing in pots.
H x S: 1m x 50cm
- How to grow Dahlia ‘Trelyn Kiwi’
- Buy Dahlia ‘Trelyn Kiwi’ from Pheasant Acre Plants
Dahlia ‘Pianella’
Carmine red with white tips, this semi-cactus dahlia is compact and suitable for growing in pots.
H x S: 90cm x 30cm
- How to grow Dahlia ‘Pianella’
- Buy Dahlia ‘Pianella’ from Le Rose di Firenze
Dahlia ‘Marlene Joy’
Cactus dahlia with huge white flowers with pink tips and a yellow central flush, up to 20cm across.
H x S: 1.5m x 90cm
- How to grow Dahlia ‘Marlene Joy’
Dahlia ‘Ryecroft Zoe’
One of the Ryecroft series of dahlias, ‘Ryecroft Zoe’ is a small-flowered cactus dahlia, bearing peach-pink blooms with a yellow centre, on stems 1.5m tall.
H x S: 1.5m x 90cm
- How to grow Dahlia ‘Ryecroft Zoe’
- Buy Dahlia ‘Ryecroft Zoe’ from Pheasant Acre Plants
Dahlia ‘Oakwood Goldcrest’
Dahlia ‘Oakwood Goldcrest’ is a hard-to-find semi-cactus dahlia, with large, lemon-yellow spiky blooms.
H x S: 1.1m x 30cm
- How to grow Dahlia ‘Oakwood Goldcrest’
Dahlia ‘Ruskin Bride
One of the Ryecroft series of dahlias, ‘Ryecroft Zoe’ is a small-flowered cactus dahlia, bearing peach-pink blooms with a yellow centre, on stems 1.5m tall.
H x S: 1.2m x 30cm
- How to grow Dahlia ‘Ruskin’s Bride’
Dahlia ‘Doris Day’
Dahlia ‘Doris Day’ is a small-flowered cactus dahlia, with small, bright red blooms.
H x S: 1.1m x 40cm
- How to grow Dahlia ‘Doris Day’
Dahlia ‘Frigoulet’
Dahlia ‘Frigoulet’ is a semi-cactus variety, producing dramatic bi-coloured red and white spiky petals. It’s a good variety for exhibiting.
H x S: 1.1m x 40cm
- How to grow Dahlia ‘Frigoulet’
- Buy Dahlia ‘Frigoulet’ from J Parker’s
Dahlia ‘Weston Miss’
Dahlia ‘Weston Miss’ is a miniature-flowered semi-cactus type, with pale yellow petals that stand out well at dusk.
H x S: 1.2m x 40cm
- Buy Dahlia ‘Weston Miss’ from Pheasant Acre Plants
Dahlia ‘Preference’
Dahlia ‘Preference’ is a small flowered semi-cactus dahlia, with yellowy pink blooms.
H x S: 1.2m x 40cm
- How to grow Dahlia ‘Preference’
- Buy Dahlia ‘Preference’ from Farmer Gracy
Dahlia ‘Reverend P. Holian’
Dahlia ‘Reverend P. Holian’ is a giant-flowered semi-cactus dahlia. Grow in rich soil for best results.
H x S: 1.2m x 40cm
Dahlia ‘Yellow Galator’
A medium-flowered cactus dahlia, ‘Yellow Galator’ has beautiful, sunny yellow flowers.
H x S: 1.2m x 50cm
Dahlia ‘Hollyhill Quintessence’
A seedling of classic show flower ‘Pink Jupiter’, Dahlia ‘Hollyhill Quintessence’ bears full, semi-cactus, white-centred pink blooms.
H x S: 1.2m x 30cm
- How to grow Dahlia ‘Hollyhill Quintessence’
Dahlia ‘Kenora Sunset’
Dahlia ‘Kenora Sunset’ bears large, bi-coloured, red and yellow blooms, measuring up to 17cm across.
H x S: 1.5m x 50cm
- How to grow Dahlia ‘Kenora Sunset’
Where to buy cactus and semi-cactus dahlias
- Dahlia tubers are available to buy from February. Most garden centres have a good selection but the best range can be found online
- Bear in mind that dahlias come in different sizes – some are dwarf types, suitable for bedding displays, others are medium-sized and good for pots, while some are large and better suited to a large border or cutting patch
- Check that you have the right conditions to grow dahlias – they need a sheltered, sunny spot
- If you’re buying tubers at the garden centre, check that they are large and plump, with no signs of rot or mould
