How to Plant Dahlia Tubers for a Summer Full of Colour

Everything You Need to Grow Spectacular Dahlias from Tubers – From First Planting to Full Bloom

There’s something truly magical about dahlias. Whether you’re a seasoned gardener or just starting out, planting a few tubers in spring is one of the simplest ways to guarantee a sensational show of flowers right through summer and into autumn.

We’ve been growing and trialling different varieties of dahlias for decades and can honestly say they never fail to impress – whether in borders or pots.

They come in all shapes, sizes and colours, from the aptly named Dahlia ‘Dinner Plates’, dazzling with massive blooms, to the adorably playful Dahlia ‘Pom Pom’ Mix, and the best part? You don’t need a huge garden to enjoy them. With a bit of care and attention, a single tuber can become a bloom-filled plant you’ll be proud of.

So, whether you’ve already received your tubers or you’re just thinking of trying your first few this year, here’s everything you need to know about planting and maintaining dahlias.

What Are Dahlias?

Dahlias are half-hardy perennials that produce bold, often flamboyant blooms from midsummer right through to the first frosts.

At YouGarden, we’ve carefully selected varieties that offer maximum flower power and garden performance – including dinner-plate giants like ‘Café au Lait’, the bold Dahlia ‘Blackberry Ripple’, and the star of the show itself, Dahlia ‘Fringed Star’, amongst so many other varieties.

With their vibrant colours and dramatic forms, they’re real show-stealers in beds, borders, patio pots or even cut flower displays. Dahlias are also fantastic for pollinators – bees and butterflies can’t resist their open-centred forms.

What Are Tubers?

When you order dahlias as tubers, you’re receiving a chunky, slightly knobbly root system – they look like a bunch of small potatoes joined together.

These tubers store all the energy the plant needs to spring into life once the weather warms. Tubers are ideal for gardeners because they’re easy to handle, straightforward to plant, and give a great head start over seeds or plugs.

Once established, they bulk up each year, producing even more flowers the following season – and you can lift and store them over winter for repeat displays.

With just a little care, dahlias will reward you with months of fabulous, flamboyant colour – they’re an all-time garden favourite for a reason!

When Is the Best Time to Plant Dahlia Tubers?

Mid to late spring is the ideal time to plant Dahlia tubers in your garden – around late March to early May, at a time when you feel almost certain the worst of the frosts are behind us.

Tubers can be started off indoors in pots from March to get earlier blooms or wait until the soil outside warms up if planting directly. Remember, they hate cold, wet soil, so it’s always better to delay, rather than rush.

How to Plant Dahlia Tubers: Step-by-Step

1. Dahlias love a sunny, sheltered spot with rich, free-draining soil. If your soil’s heavy, work in plenty of compost or grit first.
2. Check the tuber is firm and healthy, with a visible central crown or eye – this is where shoots will appear.
3. Dig a hole about 10–15cm deep. Lay the tuber on its side with the eye (or old stem) facing upwards.
4. Backfill with soil and water lightly. Mark the spot – shoots can take a couple of weeks to appear.
5. If you want to grow in a container, use a 50cm wide pot filled with free-draining compost. Keep indoors in a frost-free spot until planting out after the last frost.

Ongoing Care for Dahlias

Once shoots are around 20cm tall, pinch out the growing tip to encourage bushier plants and more blooms.

As long as you incorporate some organic matter in the planting hole when growing directly in the ground, your Dahlias shouldn’t need any feeding. However, you can boost the flowering of those in containers by applying a potassium-rich liquid fertiliser once a fortnight, from July to September.

Be sure to water regularly, especially in pots or dry spells, but don’t overdo it early on or you risk rotting the tuber.

Deadhead spent blooms to keep the show going and support taller varieties with stakes before they get top-heavy. After the first autumn frost blackens the foliage, lift the tubers, clean them up, and store them somewhere dry and frost-free over winter – a garage or shed will do.