How to plant dahlias in pots

1. Choose the right variety

Which types of dahlias are best for pots? Choose dwarf or low-growing varieties. These compact types stay nicely shaped and don’t need overly large pots. They also tend to flower abundantly.

If you prefer a taller variety, just be sure to use a larger, deeper pot to support the weight of the growing plant. Each dahlia tuber needs about 30 to 60 centimetres of space, so in most cases you’ll only plant one tuber per pot.

TIP: Combine colours with your pot style and surroundings for a cheerful and stylish look. Scroll down for our favourite varieties for containers.

2. Choose the right pot

You can use many types of containers, but drainage is key – make sure your pot has holes at the bottom. Dahlia tubers do not like wet feet. The pot should be at least 35–40 cm in diameter, and ideally as large as possible. It doesn’t matter if it’s plastic, ceramic, terracotta, wooden, or metal. Even a decorative zinc bucket or old wine barrel will work beautifully. 

We love terracotta – it’s durable, breathable, and looks great too.

TIP: You can also use affordable builder’s buckets. Just drill a few holes (around 1 cm) in the base. Not so pretty? Tuck them behind your more decorative pots.

3. How many dahlias per pot?

We recommend planting 1 tuber in a 35–40 cm pot. If your container is larger than 50 cm, you can plant 3 tubers, or even 5 if they are compact varieties. 

Don’t overcrowd the pot: the plants will stretch toward the light and produce fewer blooms.

4. When to plant

Start planting dahlia tubers in pots indoors around mid-April. This gives them a head start and means earlier flowers. After the last night frost – usually after mid-May – you can move the pots outdoors. Keep an eye on the weather forecast. 

Let your plants get used to outdoor conditions slowly by placing them outside during the day, though we know this can mean a bit of pot juggling.

TIP: Indoors, dahlias tend to grow toward the light. Turn the pots now and then to keep growth balanced.

5. Choose the right potting mix

Cover the drainage holes with shards from old pots. Add a layer of hydrograins or gravel. Then fill the pot with general-purpose potting soil (preferably sustainably sourced).

Keep the soil light and loose – don’t press it down. Make a shallow hole for the tuber. Dahlias love warmth, so plant the tuber about 2 cm below the surface. Place it upright, with the old stem pointing up, in the centre of the pot.

TIP: Mix your soil with one-third compost and add a little organic fertiliser to the planting hole if desired.

6. Provide support

If you choose a tall-growing dahlia variety, it will need some support as it grows. You can use bamboo stakes from the garden centre, or a sturdy branch from your own garden.

As the plant grows, tie it loosely to the stake using soft plant ties. Rubber-coated wire is gentle and plant-friendly. You can also use a metal plant support – these usually have two legs and a curved ring to hold the plant upright.

TIP: Insert the support at the same time you plant the tuber, so you don’t accidentally damage or pierce the bulb later.

7. Care

After planting, water the soil lightly: don’t soak it. Use a watering can to moisten the soil gently rather than using a hose. Wait for the first green shoots to appear. Keep watering during dry spells, but always check if the soil is too wet. Keep slugs and snails away in the early stages. And don’t forget, cut your blooms regularly for lovely home bouquets or a cheerful gift.