I also have been wondering about this. I rarely watered the entire growing season. The plants grow vigously and continue to bloom, but as of late, the temperature has dropped significantly and it has begun to rain a lot. Would the first frost suggestion still apply ? Or should they be dug up earlier if rainy conditions persist. I would imagine the tubers would rot in persistently cold wet soil.

I'd still wait for a killing frost. I find that letting them be knocked down by frost, cutting the stalks and then waiting a week or two to dig them that they store better.

tj

What's the best way to store them?

"I would imagine the tubers would rot in persistently cold wet soil."

You are correct... Even worse is the slow rot that eats the tubers inside out during storage, thought to be a result of heavy cold rains and fertilizing with nitrogen late in the season.

Not every dahlia grower receives a killing frost to mark the end of a growing season, so as long as the tubers have had three months of growth, you should have mature tubers that can make it through storage. There is no need for a killing frost... That is an unproven myth.

Thank you! If the soil gets a chance to dry out weekly in between showers, I'll leave them In the ground until frost, if not, I'm digging them up before then. I'd be saddened to have them rot on me after having them surpass all of my novice expectations all season long.