I don’t know where the rumor started that dahlias don’t do well in containers.
Sure, some of them are big, so you need an equally large container, but they do extremely well in pots. There’s no reason you can’t bring dahlias into your life in a pot.
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You can add a little color to your patio with some low-growing decorative dahlias or make a big, dramatic statement in the garden with a handful of dinnerplate tubers and a bold container.
The cottage garden vibe is right within reach, even if you don’t have a yard (the cottage is also optional).
Growing dahlias in containers differs slightly from growing them in the ground, but it’s no more difficult.
In fact, in some ways, it’s easier to help them thrive in a container because you can adjust the environment more easily.
Are you ready to make it happen? Great, let’s dive in. Here’s what we’re going to discuss:
What You’ll Learn
Before we jump in, let’s talk a little bit about dahlia anatomy. These plants grow from edible tubers that look like tiny, pointy potatoes.
This plant was actually first cultivated for its roots rather than the flowers, but it’s the flowers that made it such a popular garden option.
These tubers grow wide rather than deep, spreading as the plant continues to develop. From the eyes of those tubers emerge leaves and long stalks that will hold the flower heads.
Most dahlia types can support the weight of the flowers, but we humans have bred a few that become so top heavy that they need support.
All that is to say that you need to be choosy about containers and the cultivar that you select. So let’s talk about the first element of that equation to start.
Pick a Container
In order to pick the best container, we need to consider the dahlia’s underground structures. Since the tubers spread outwards rather than growing deeper, you want a pot that is wider than it is deep.
I never suggest that people fill the bottom of their containers with rocks because it doesn’t improve drainage, which is usually the goal.
But in this case, if you decide you like the look of a tall container, feel free to put some rocks in the bottom to add some weight and take up some room. It’s not necessary, but it’s an option that’s available to you.
The thing to keep in mind here is that you need about 18 inches of depth for the tubers to grow in.
So if you choose a big old pot that is 24 inches in diameter and 36 inches deep, you could fill up a foot or so of the base with rocks if you wanted.
The material of the pot doesn’t matter much, so go with what you love. Terra cotta can be a bit delicate, but it’s affordable and drains well.
Plastic is also affordable and it doesn’t heat up like terra cotta and metal can. Glazed ceramic and concrete are always good options if you want something substantial.
Regardless of what you end up with, the pot must have drainage holes. Dahlias are very sensitive to rot, so if the container doesn’t drain well, the tubers will be toast before you can blink.
If you’re reusing a container, wipe it clean with soapy water. You’ll be sorry if you spread some awful disease to your new plants just because you didn’t clean the pot out.
If you want to be able to more easily move your pots, whether to change up the display or follow the sun, you might want to put your containers on casters.
Choosing a Potting Medium
These days, we’re lucky enough to have lots of killer options for potting soil. Look for one that is water retentive and porous, so it drains well.
A good mix for dahlias will typically contain some combination of rice hulls, sphagnum moss, perlite, coconut coir, or composted plant matter.
I personally love FoxFarm’s Ocean Potting Soil.
It contains sphagnum moss, aged forest and ocean plant matter, sandy loam, earthworm castings, bat guano, and fish meal to give plants a loose, rich bed.
Plus, the company that makes it is a small, family-owned business based out of California.
I highly recommend it for pretty much all container growing. If you want to give it a try, purchase a 12-quart bag on Amazon.
Best Dahlias for Containers
The one thing that will set you up for success more than anything else, except possibly providing good drainage, is choosing the right cultivar.
If you pick an extremely tall, heavy cultivar, you’re going to have a bigger challenge on your hands.
That’s not to say that there are any dahlias that can’t be grown in containers – they all can. But consider how much work you want to put in to maintain these plants and help them to thrive.
For instance, while it’s possible to grow dinnerplate dahlias in a container, the pot needs to be huge. They grow five feet tall or more and need staking, so you’ll need at least a 10-gallon pot.
Look for smaller types. Trust me, the visual impact won’t be small. The following are just a few of the excellent options out there:
Bishop of Canterbury
‘Bishop of Canterbury’ seems tailor-made for container life. The three-foot-tall plant can be pinched back to keep it shorter and encourage more blossoms.
The plum-colored petals surround a center of golden-black disc florets, catching all the attention in the garden. Mix it with a trailing option like yellow petunias for twice the impact.
Get started by picking up two, four, or eight tubers at Eden Brothers.
Small World
As the name implies, ‘Small World’ brings a world of dahlia delight in a petite footprint. The plant reaches about a foot tall and is covered in round pompoms of pure white blossoms.
Eden Brothers carries packs of two, four, or eight tubers.
Totally Tangerine
Honestly, every time my ‘Totally Tangerine’ plants start to bloom, I have to do a double-take.
I’ve seen them a million times, but the vibrant anemone flowers made up of pink, tangerine, purple, and fuchsia hues are just so unique.
While there are lots of flowers and the plant grows up to three feet tall, the blossoms aren’t heavy, so ‘Totally Tangerine’ works well in a pot.
Witness the beauty for yourself by picking up two, four, or eight tubers at Eden Brothers.
Sowing Seeds
You can absolutely start dahlias from seed in containers.
In fact, it can be a nice way to extend the growing season because you can start the seeds indoors and bring the seedlings outside when the time is right.
Seeds can be sown indoors about 12 weeks before the last predicted frost date in your region, or after the last frost for starting outdoors. Sow the seeds about a quarter-inch deep in the soil.
One trick I learned from a friend who breeds dahlias is to plant the seeds closer to the edge of the container than the center.
Once the growing roots hit the side of the container, they start to rapidly swell and develop into tubers.
This will happen eventually regardless of whether the roots come up against something solid, but it will happen faster if they do.
Use a spray bottle to mist the soil. You want to moisten the soil without moving the seeds around.
If the plants are growing indoors, put them under grow lights for about eight hours a day. Outdoors, keep the containers in a spot that receives eight hours of direct sunlight.
Planting Tubers
In your filled container, plant the tuber about four inches deep in the soil.
Ideally, you should center the eye of the tuber in the pot, but it doesn’t really matter. The tuber will eventually fill out the pot anyway.
If you want to be extra careful to avoid rot, fill the container up to about six inches below the rim and place the tubers inside.
Barely cover them with soil. Let the soil dry out to the bottom of the tuber between watering.
Once the tuber sends up a stem, add a few more inches of soil. When the stem reaches above the rim of the pot, fill the pot the rest of the way.
This process takes more time, but it allows the tuber to dry out more readily.
Maintenance
When you plant your seeds or tubers, add any sort of support that you plan to use at that time to lessen the chance of disturbing the roots.
Remember, shorter types don’t need support, but taller types might. This could be as simple as a stake, or you could use tomato cages or special flower supports.
I think flower support rings look better in containers, personally. These four-millimeter wire cages from HiGift can be purchased in 15.8- or 24-inch heights on Amazon.
You might need to drill holes in the side of the container and affix the support to the side of the pot using wire.
Once the plants are between six inches and a foot tall, pinch them back to a flower bud to encourage bushier growth.
As the tubers are developing, you need to be extraordinarily careful not to overwater. Remember, dahlia tubers are extremely prone to rotting.
The soil should be allowed to dry out to the middle of the tuber between watering.
If you live in a hot region, when the heat of summer rolls around, you might want to provide your plant some relief if the container is sitting on concrete. That could mean setting the plant somewhere that will be shaded during the hottest part of the day.
Remember that any pest or disease that can attack in-ground dahlias can attack ones that are growing in a pot well.
Our general guide to growing dahlias will walk you through what to watch for. I find that potted flowers seem to have more trouble with aphids and spider mites than in-ground plants.
In the fall, lift the tubers and overwinter them unless you live in USDA Hardiness Zones 9 or 10. Our guide to lifting dahlia tubers explains the process.
Once you lift the tubers, you probably want to do some dividing before you repot them the following spring. You should also use fresh soil, and remember to clean those pots!
Dahlias are Delightful in Containers
Not everyone with a green thumb or a passion for flowers is lucky enough to live somewhere with a big yard full of lots of unoccupied sunny spots.
In fact, most of us probably have to make do with something less than ideal. That’s why I’m such a fan of growing things in containers.
It doesn’t matter what your garden situation looks like. So long as you have a few square feet of sunny space and a sturdy container, you can enjoy everything that dahlias have to offer.
Last but not least, let’s get down to the important stuff. What cultivar are you growing? Where are you keeping your potted beauty? Did we miss a particular favorite of yours that you’d like to call out? Share the details in the comments.
And don’t go just yet. If you have any interest in learning more about dahlias, you might want to stick around to check these articles out next:
I am really bothered by that badly photoshopped photo of the dahlias in containers at the end. I really wanted to believe it, but I think it is badly faked. There are multiple different bloom styles on single plants and thus my confidence in growing dahlias in containers is shaken. I wish I could see some pictures of real dahlias growing in small pots like that. I don’t even think you could grow two varieties in a single pot that small. Disappointed and confused. 🙁
I absolutely love dahlias. All of them. However, I have no success with growing them, either inground or in pots. Something likes to dine on them and does so much damage that I end up tossing them. I might try it again this year.
Hi Kathryn, that is one of the downsides of dahlias. Those tubers are tasty to pests, herbivores, and humans! It sounds like you might benefit from growing in a container to try and keep them away from pests.