I recently picked up some large 50L pots for my dahlia tubers because I've heard they prefer bigger containers. However, I've also read that they dislike overly wet conditions, so I'll make sure to choose a good potting mix. I'm considering planting my tuber in a smaller 8-inch pot for now until it starts growing leaves, and then moving it to the bigger pot. My concern is whether I should be worried about the last frost since I don't have a greenhouse or shed space. I do have a pergola canopy set up, but it's open to wind. Is frost only an issue for dahlias that are directly planted in the ground?
5 Answers
It's best to lift and store dahlia tubers during winter for strong growth next year. I once kept mine in a pot on my patio, and while it survived the winter, I can’t guarantee it will do the same in future years. Check out 'in the garden with Eli and Kate' on YouTube for a great tutorial on how to store them properly!
If frost is in the forecast, I would definitely put some fleece over your dahlias. That way, they can stay safeguarded.
Bringing them inside is the safest bet when frost is expected. Dahlia tubers can get ruined in temperatures below freezing, so watch the forecast closely! In-ground tubers are generally safer as long as they’re mulched, but those in pots need more protection.
Frost actually poses a bigger threat to dahlias in pots compared to those planted in the ground, since the soil in the ground acts as an insulator. As long as your potting mix drains well and you keep it on the drier side, your tubers might handle the light frost just fine. If you're really unable to bring them indoors, just be cautious during the chilly nights!
I planted mine a couple of weeks ago and buried them down deep. Unless you’re in a really cold area, they should be fine against light frosts. If any shoots start popping up, just cover them with a cloche overnight to protect against the cold.
Thanks for the tip! I'll make sure to keep an eye out for shoots and cover them.