When to Start Dahlias Indoors in Minnesota (And How to Pot Up Tubers Early)
So, you got your hands on those dahlia tubers, and you’re dreaming about armfuls of blooms this summer. Then the weather man calls out…
BLIZZARD
If you’re staring at your dahlia tubers wondering, “Now what am I supposed to do with these until May?” don’t worry. You actually have great timing.
Let’s talk about how to hold onto those tubers—and even give them a little head start—until we can safely plant them outside here in Minnesota (usually around May 15).
When to Start Dahlias Indoors in Minnesota
If you live in Minnesota, you can start dahlia tubers indoors about 4–6 weeks before your last frost, which is typically around May 15 in southern Minnesota.
That means right now is actually perfect timing to pot them up and let them wake up.
Starting dahlia tubers early gives them a head start so they’re already growing when it’s finally warm enough to plant them outside.
And after a long Minnesota winter, it’s pretty fun to see something green growing again.
What to Do If You Bought Dahlia Tubers Too Early
Good news: you have two easy options.
You can either pot them up early and start growing them indoors, or you can store them safely until planting time.
Both options work just fine.
Option 1: Pot Them Up for an Early Start
If you're itching to get your hands in some dirt (I get it), you can pot up your dahlia tubers now.
All you need:
A small pot or container
Regular potting soil
Your dahlia tuber
Place the tuber in the pot with the eye facing up (that’s where the sprout will come from). Cover it with a few inches of soil and give it a light watering.
Then place the pot somewhere bright inside your house.
Over the next few weeks the tuber will wake up and send up little green shoots (sometimes this can take 2-4 weeks). When planting time arrives in May, you’ll already have a strong plant ready for the garden.
It’s basically giving your dahlias a head start on summer.
Option 2: Store Them Until Planting Time
If you're not ready to start growing them yet, you can also store your dahlia tubers until it’s warm enough to plant them outside.
Dahlias like to be stored somewhere that is:
Cool
Dark
Above freezing
Good storage spots include:
An unheated garage
A basement
A cellar
Place the tubers in a box with peat moss or wood shavings to keep them from drying out.
Check on them every couple weeks just to make sure they aren’t shriveling. You can mist them lightly if they look dry.
Why Starting Dahlias Early Can Be Worth It
On our flower farm, I often pot up some of our dahlia tubers early so they wake up and start growing.
Once they start sprouting, I can take cuttings from them to grow even more plants.
(That’s a whole topic for another blog.)
But even if you’re not taking cuttings, starting dahlias early can give you bigger, stronger plants when they finally go into the garden.
And if you’re new to dahlias, here’s the thing to know: they might look fancy, but they’re actually very generous plants.
Plant one tuber and you’ll get:
🌸 Blooms from mid-summer until frost
🐝 Bees happily buzzing around your garden
💐 Armfuls of flowers for your kitchen table
Even better? The tubers multiply every year, so your flower stash keeps growing.
Once you start growing dahlias, it’s very hard to stop.
Ask any dahlia grower. We all start with just a few.
Where to Buy Dahlia Tubers Near Mankato
If you’re thinking about dabbling in dahlias this year, we’d love to help you get started.
We’ll have a variety of dahlia tubers available at our upcoming sale:
📍 The 507 Outskirts, New Ulm, MN
📅 March 21st
⏰ 9:00am – 12:00
Come grab a few tubers, ask all your dahlia questions, and start dreaming about a backyard full of blooms.
Fair warning though…
You might come for three and leave with ten.
It happens to the best of us. 🌸
FAQ: Can you plant dahlia tubers outside in early spring in Minnesota?
No. Dahlias are very frost sensitive and should not be planted outside until the danger of frost has passed. In southern Minnesota, that’s usually around May 15. Until then, tubers can be started indoors in pots or stored in a cool, dark place until planting time.