Dahlias are very frost tender whether seed or tuber raised. Any hint of a freeze will turn them to mush. I wouldn't risk it. Have you got somewhere you could put them to slow them down a bit: light, cool but frost free?

Yup.

Maybe put them outside during the day and bring them in at night? You would get a head start at the hardening off process so once it's warm enough to plant them outside you would be in good shape.

If they get too tall, pinch 'em off. In the long run that will result in bushier plants - a good thing.

Kevin

flora said: Any hint of a freeze will turn them to mush.

and i will say that any hint of FROST.. will do mostly the same ...

ken

Thanks for the advice. What's the best way to pinch them off and will they be okay in their three inch pots until transplant time?

if you look.. VERY CLOSELY ... you might.. its been a very long time.. see tiny dormant buds at each leaf to trunk interface ...

you could cut above any of those.. to trigger them into growth ...

just as i used to do.. when i was cutting flowers from them

ken

Ken is correct. You can pinch them anywhere along the stem and they will send out new shoots from where the leaf meets the stem. It's hard to say if they will outgrow their 3 inch pots. Keep an eye on the bottom of the pot. If you see a lot of roots coming out the bottom drainage holes, it's probably a good idea to repot into something larger.

Kevin

they should do ok in small pots. It slows them down somewhat, a kind of Bonsai effect, but that should be helpfull in your case.

After starting annual stuff from seeds for the balcony and potting up Dahlia tubers to give them a head start for several years now, I am delighted every season about the kind of growth explosion the plants go through after being transplanted into open soil or window boxes.

As long as you get your Dahlias through to the transplanting without overwatering (fungus) or keeping them too warm, they should recover.

And do prune them after transplanting in case they got extremely leggy and have thin stalks/shoots that tend to bend/break. They regrow new sturdy shoots in no time in a nice sunny border.
Good luck, bye, Lin