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Dahlia Tubers

Dahlia tubers are available to plant in spring for summer blooms that are the show-offs of the border with their strong, sculptural shapes, sizes and host of dazzling colours. These popular, long-flowering perennials produce blooms through the summer right up to the first frosts. Choose an open flowered variety like dahlia ‘Waltzing Matilda’ to attract plenty of pollinators to the garden or the eye-catching cactus flowered type dahlia ‘Yellow Star’ to delight the eye. Find perennial colour to pair with your dahlias in our extensive collection of flower bulbs & tubers.

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Are dahlias perennials?

Dahlia plants are perennial. This means they return every year with fresh green growth in spring and blooms in summer. They’re classed as tender perennials because they don’t like too much cold. In the south, the tubers can be left in the ground with a thick layer of mulch but further North or in frost pockets, it’s better to lift the tubers and store them over winter until spring. Dahlias die back in the autumn, putting all their energy into their tubers to overwinter and sprout again come spring.

When to plant dahlias

Plant your dahlia tubers outdoors in May or until all risk of frost has passed in your area. You can get your tubers started earlier in the year in March by planting them in pots under cover or in an unheated greenhouse which may result in earlier blooms. Use a well drained, peat-free potting mix to start your tubers in pots. If you want to skip the potting, start with garden ready varieties fresh from our exciting range of dahlia plants at Dobies.

When you plant your dahlias into their final position, use a sturdy plant support like a stake to keep your plant upright to encourage long, straight flower stems to form. Mulch around the base of your developing plants to keep the roots cool and moist.

Do dahlias come back?

Dahlias do come back to flower the following year as long as you protect your tubers from frost. Do this by gently lifting the tubers at the end of autumn before the first frosts. Brush off any soil from your tubers and store them in a cool, dark place through the winter months. An unheated shed or garage is perfect. When spring comes around, simply soak your tubers in water for an hour to rehydrate them ready for planting in pots or fertile, free-draining ground.

When do dahlias bloom?

Dahlias start to bloom in midsummer. Early blooms appear in July, and carry on flowering through to early autumn and the first frosts. Encourage continuous blooms by regularly deadheading your dahlias. Dahlias flower much better when they receive long hours of daylight in the summer, so choose a spot that sees lots of sun when you plant your tubers.