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Australian Guide to Growing Dahlias in Pots

These plants grow from underground tubers and are ideal for growing in large pots.

Dahlias are one of my favourite flowers to grow in the garden. They provide masses of gorgeous blooms from late spring right through the summer and into autumn. 

These plants grow from underground tubers and are ideal for growing in large pots. In fact, I have two dwarf dahlias that I’ve been growing for a number of years now.

I have one planted in a sunny spot in the garden and another one in a large pot that also gets plenty of sunlight. I find that the one in the pot always springs to life sooner than the one grown in the ground.

The potted dahlia also seems to flower for longer, right into autumn. I believe that the reason for this is that the soil in the pot warms up faster than the ground soil and retains its warm temperature for longer.

Here’s everything you need to know to grow dahlias in pots successfully.

Choose a large pot

For your potted dahlia, you want to choose a large pot that is at least 30 cm in diameter. The one I’m using is a lovely stoneware pot that is 35 cm in diameter. 

dahlia in pot 2 | Plant care

This accommodates my dwarf dahlia well as it thrives and grows. Make sure that the pot has plenty of drainage holes and choose a sunny spot to place it.

Select the perfect variety to grow in your pot

For growing in pots, I prefer the dwarf dahlias because they’re a nice compact bushy plant and produce lots of colourful flowers. As the plant is relatively compact, you’ll find that the flowers won’t need staking when grown in a pot.

Dwarf dahlia | Plant care

Taller varieties of dahlias will have to be staked to keep the flowers from falling over as they get quite top-heavy. 

If you choose to grow any of the taller varieties, place three stakes around the edges of the pot before you put the plant in. This will avoid damage to the tuber and will support the growing plant if you fasten some twine to the stakes to make a sort of cage.

You can grow dahlias from seeds, tubers or by purchasing a plant from a nursery. I purchased mine as a nursery plant that was already blooming because I adored the colour of the flowers.

Seeds are best sown in spring unless you start them indoors because they’ll need some warmth to germinate. You can plant tubers in the winter as they’ll be dormant until the soil warms up.

Or, do what I did and visit your local nursery and purchase a plant or two that already has flower buds on it for some instant gratification.

Potted dahlia | Plant care

You’ll want to ensure that you only place one plant in each pot so that the roots and tubers have enough space to grow.

Use a premium potting mix to grow your dahlias in

Your dahlias will thrive when they’re grown in a premium potting mix that drains freely. Most quality mixes will also contain some fertiliser that will usually feed your plants for around 6 months.

Caring for your potted dahlias

Caring for your potted dahlias is fairly easy. All you have to do is keep the plant watered while it’s in active growth. Dahlias prefer moist soil that drains freely.

Once your plant starts to produce flowers, try to deadhead these as often as you can as this will force the plant to produce more and more flowers. The flowers are also great for bringing inside and putting in a vase.

dahlia in vase | Plant care

For my potted dahlia, I like to add some slow-release fertiliser pellets in early spring to give them a boost through the growing season. I use one that is designed for flowering plants to ensure that it contains plenty of potassium.

You could also opt to use a liquid fertiliser and apply this every two weeks as part of your watering schedule. Once again, select a liquid feed that is specifically made for flowering plants.

In late autumn or early winter, your plant will die down and you can then cut it back all the way to the soil level. Don’t worry, it will spring back into life once the weather warms up in spring.

Generally, there’s no need to lift your dahlia tubers over winter. I live in the southern part of Victoria and don’t even move my pot during winter.

However, if you do live in a cold region that gets heavy frost, you can just move your pot to a sheltered spot where it won’t get frosted.

FAQ

Will potted dahlias come back every year?

Absolutely! I have had a dwarf dahlia growing in a large pot for a number of years and it comes back again every spring and produces masses of gorgeous blooms.

Do dahlias like sun or shade?

Dahlias prefer a sunny spot in your garden. They need a minimum of 6 hours of sunlight daily in order to thrive and produce plenty of lovely flowers.

Photo of author

Annette Hird

Annette Hird is a gardening expert with many years of experience in a range of gardening related positions. She has an Associate Diploma of Applied Science in Horticulture and has worked in a variety of production nurseries, primarily as a propagator. She has also been responsible for a large homestead garden that included lawn care, fruit trees, roses and many other ornamental plants. More recently, Annette has concentrated on improving the garden landscape of the homes that she has lived in and focused a lot of energy on growing edible plants as well. She now enjoys sharing her experience and knowledge with others by writing articles about all facets of gardening and growing plants.

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