How to grow dahlias in pots

Dahlia 'Roxy'
Dahlia 'Roxy'

While everything else in the garden is fading, the blousy blooms of dahlias are still going strong. But how do you grow them in pots and what are the best varieties to try?

You can now buy much more compact plants, thanks to advanced breeding techniques. These will provide you with bushy plants with interesting foliage and flowers that hold themselves above the leaves. The dark-leaved cultivars are a feature in themselves.

Planting up

Plant tubers in John Innes No.3 loam-based compost and insert slow-release fertiliser tablets at planting time to keep the plant well fed. Use pots at least 30cm in diameter to give the tuber plenty of room to grow. As the shoots reach 10-12cm, pinch out the tops to boost bushy growth.

Feed and water

Remember that dahlias are really hungry plants, so will need regular feeding and watering; if they get too dry, they are susceptible to powdery mildew. Once in flower, deadhead regularly, which will keep them going and encourage them to produce more flowers.

Good types to try

It rather depends on the size of your pot, but if you want a dwarf form, D. ‘Roxy’ is a good bet as it has bushy deep burgundy foliage and vibrant deep pink blooms. Other small varieties that pack a punch include the deep orange ‘Bishop of Oxford’, with its dark foliage.

Anemone-flowered dahlias look elegant in pots. Try ‘Mystic Illusion’, which has rich dark foliage and striking yellow flowers that aren’t too tall and don’t need staking.

If you have a large pot, appreciate huge, showy blooms and are prepared to stake them, try the pink ‘Sir Alf Ramsey’. You may get only one flower per month but when you do, it will have been worth the wait.