After spending the winter tucked away in storage, your dahlias are probably itching to get back into the garden. While you could just wait for spring to warm up the soil, there’s a great little trick to get a head start on the season: “pre-starting” or waking them up early indoors.
Why You Should Pre-Start Your Dahlias
The biggest perk of starting your dahlia tubers early is that you’ll see those gorgeous blooms much sooner. By the time the weather is warm enough to plant outside, your dahlias will already have a head start with established shoots. Instead of spending the first few weeks of summer just trying to break through the dirt, they can focus all their energy on growing tall and pumping out flowers.
Another huge plus? It’s a total game-changer for pest control. Slugs and snails absolutely love tender, young dahlia sprouts. By pre-starting them, the plants are already a bit taller and sturdier by the time they hit the garden, making them much less of a snack for those garden pests.
Watch Out for Late Frosts
Since your pre-started dahlias will already have green growth above the soil, they’re a bit more sensitive to the cold than a dormant tuber. A surprise night frost can easily zap those fresh leaves if they aren’t protected. Luckily, since we usually wait until the weather stabilizes to move them outside, this isn’t a huge issue—but keep some garden fleece or an old blanket handy just in case you need to tuck them in during a cold snap.
When to Move Them Outside
Once May rolls around and the threat of frost has passed, your pre-started dahlias are ready to be transplanted into your flower beds or into their permanent outdoor pots.
The Best Spots for Indoor Growing
Just like the adult plants, dahlia tubers need the right environment to wake up properly. The best spots to get them going are:
- A sunny windowsill (ideally facing east or west).
- A sunroom or conservatory.
- A cold frame.
How to Pre-Start Your Dahlias
Ready to get growing? Here’s my step-by-step guide to waking up your tubers:
- Start by soaking your healthy tubers in a bucket of water overnight. This helps rehydrate them and gets the growth process moving.
- Grab a pot with good drainage and cover the hole with a piece of broken pottery or a large stone. This ensures water can flow out freely so the roots don’t get “wet feet” and rot.
- Fill the pot with loose, high-quality potting soil. Plant the tuber about four inches deep, cover it back up with soil, and give it a good drink of water.
- Place the pot in a warm, bright spot and keep the soil consistently moist (but not soggy).
- Once you see green shoots poking up and the outdoor temperatures are safe, you can move your dahlias into the garden or a larger planter.
A Pro Tip for Container Dahlias
If you’re planning on keeping your dahlias in pots for your porch or patio, save yourself some work by starting them in a large enough container right from the beginning. And don’t forget—once they start growing, it’s a good idea to start feeding your dahlias with a little fertilizer to give them the nutrients they need for those show-stopping blooms!
