Growing Dahlias in Pots: The Questions I Get Asked The Most

One of the most common questions I get each year is “Can you grow dahlias in pots?”

The short answer is YES - absolutely. Dahlias grow beautifully in containers and are perfect for patios, decks and smaller gardens. But there’s one reason that many potted dahlias fail… and it’s surprisingly simple.

Most people plant them in pots that are far too small.

The Real Reason Your Potted Dahlias May Struggle

It’s not that dahlias don’t grow well in pots - it’s just that they don’t like being cramped.

Many of the popular dahlia varieties grow over 1 metre tall, which means they need plenty of root space to support all that growth! Plus, when planted in small containers, their soil dries out incredibly quickly during the summer. That means your dahlias need watering constantly (that means every single day on peak summer days!).

And if you go away for a few days and forget? You often come back to very sad (or completely dead) dahlias. The ultimate heartbreak!

The Three Things Dahlias Need in Pots

If you get these three things right, most dahlias will grow happily in containers.

1. Plenty of space

Choose a pot large enough for the roots to develop properly - and don't overcrowd your tubers!

2. Free-draining soil

Use a good quality compost that allows water to drain easily.

3. Consistent watering and feeding

During the summer I usually water daily and feed weekly (more on this below). Dahlias are hungry plants and regular watering, feeding (and pinching!) helps them produce lots of flowers.

Size Matters When Potting Your Dahlias

The key to success when growing dahlias in containers is choosing a pot that’s large enough.

For example, on my patio I grow dahlias in three large galvanised water butts that measure around 60cm wide x 75cm tall. In containers this size, I can comfortably plant three dahlia tubers together - as the larger soil volume helps retain moisture, meaning the plants stay happier through the warmer months.

However, on the deck near our garden office, I use slightly smaller containers. These pots measure around 35 - 45cm wide, and in pots this size I plant one tuber per container.

This summer I’m also creating a mini container garden using beautiful wicker planters that I've treated myself to from The Basket Company. These planters vary in size from 35cm - 55cm, so I’ll plant:

• one tuber in the smaller pots

• two tubers in the larger ones

As with Planting Dahlias in Raised Beds (which I recently wrote a blog about) the rough rule I use is keeping around 30cm of space between my dahlias, regardless of the vessel I'm potting them into. So this means, for small pots, it's easy to see why you would only plant one tuber per pot.

So... What Size Pot Do I Need For My Dahlias?

Because many dahlia varieties grow tall and produce large root systems, choosing the right container size is essential. As a general guide:

Small pots (35–40cm wide) → plant one tuber

Medium pots (45–55cm wide) → plant one to two tubers

Large containers (60cm or more) → plant two to three tubers

Larger pots hold moisture for longer and make watering much easier during warm summer weather. When in doubt, it’s always better to go bigger with your container.

The Best Soil for Dahlias in Pots

Dahlias grow best in rich, free-draining soil - and so, for containers, I usually recommend using a good quality multi-purpose compost.

Good drainage is really important because dahlia tubers don’t like sitting in very wet soil, particularly early in the season (in fact, they may rot if you get this wrong!). Adding a small amount of slow-release fertiliser when planting can also help support healthy growth, but this isn't essential.

How Often Should You Water Dahlias in Pots?

Dahlias grown in containers need more regular watering than those planted in the ground. During the summer months I will:

• water them daily

• feed them once a week

The main thing to remember is that containers dry out much faster than garden soil, especially during warm weather. Checking the soil regularly will help prevent your plants from drying out completely.

The Best Dahlias for Planting in Pots and Containers

As I've already stressed - most dahlias can be grown successfully in containers if the pots are large enough. However, some varieties are particularly well suited to container gardening.

For smaller pots, I'd recommend dahlia varieties like Totally Tangerine, Princess Nadine and Mary Evelyn. These plants stay slightly more manageable in size while still producing beautiful flowers throughout the summer. They’re also brilliant for pollinators!

If you’re planting in larger containers or statement planters, you can grow some real showstoppers. Dahlia varieties such as Rancho, Yvonne, Temple of Beauty, Great Silence and Sam Hopkins all perform beautifully in bigger pots where their roots have plenty of space to grow.

The key is to match the size of the variety to the size of your container - which sounds simple, but it's easy to get this wrong!

5 Common Mistakes When Growing Dahlias in Pots

If your potted dahlias haven’t thrived before, one of these might be the reason.

1. Using pots that are too small

This is by far the most common issue. Dahlias need plenty of root space to grow well.

2. Letting the soil dry out

Containers dry out quickly in warm weather, so regular watering is essential.

3. Not feeding regularly

Dahlias are hungry plants and benefit from weekly feeding once they start growing strongly.

4. Poor drainage

Waterlogged soil can cause tubers to rot, so using free-draining compost is really important.

5. Planting too many dahlias in one pot

Overcrowding leads to weak plants that struggle to thrive (or no plants at all!).

Can You Grow Dahlias on a Patio or Balcony?

Absolutely - yes! Dahlias are actually one of the best plants for container gardening because they flower for months and produce plenty of blooms for cutting.

With the right containers you can easily create a mini dahlia garden on a patio, balcony or deck, mixing different varieties and colours to suit your space. It's one of the many reasons I love them as, no matter what your garden situation, a dahlia can bloom!

Even just a few pots can quickly transform an outdoor area into a flower-filled summer corner and I encourage everyone (no matter how big or small or your garden is!) to give it a go.

Got further questions or want to show off your potted beauties? Tag us on Instagram @dahliabeach (we've also posted a simple step-by-step guide over there) — we love seeing what you’re growing.

A little reminder that at this time of year (April) some of our most popular dahlia varieties begin to sell out; so if you’ve been thinking about growing dahlias in pots this summer it’s worth getting your order in soon!