You can pot them up in milk cartons - you can get 3-4 to a carton- (staple the top shut, lay on side, cut the new "top" off leaving enough of a tab to write the name on) in Feb or March & grow them inside until danger of frost is passed then plant them in the garden just as you would an annual or perennial- carefully so as not to break off too many roots- although they really don't mind if you do they just put out more-- lovely things that they are!-- You can get a month or more head start on blooming by doing this- just be sure to harden them off before you plant them out. We have a neighbor that starts all hers- they're about a foot tall when we plant them out for her & she has really early blooms- & they're still blooming now at the end of the season.

Plantlady - how are you holding the cartons - in a dark cool spot? We expect freezing temps outside till at least sometime in April, and usually don't plant out annuals till the end of May. I don't have a sunny enough location in the house to have foliage - it would be spindly and weak. How long does it take the tuber to throw up foliage after you plant it? I might try this starting 30 days before planting out. We additionally have the problem of cool night time temps in May and sometimes into June. We don't get 'Hot Summer Nights' till July and August.

Alyrics,
Like you, I don't have enough sunny windows either. However, if I did, I would find that the dahlia plants might get too tall and lanky if I started them in a window and left them there.

What I do, is start them under lights ( or a window), and when they are about an inch or so high, I take them to the garage. On good days they go outside, and I haul them back in for the night or cold days. This way, they get the full sun they like ( and not filtered by the window), and they don't tend to get as tall and lanky. Also the cool weather and wind makes them get heavier stems which do them well in the summer. Mine grow about 4 feet tall, and make a spectacular show.

That is a really neat idea that plant lady has about using the milk carton. They will take up less space, and you are recycling at the same time ( a bonus). Be sure that you put drainage holes in the bottom. I like the idea of the tab for labelling. Thanks for the great tip, plantlady. Are you suggesting the 1 quart size, or the 2 quart size? I guess it depends on the size of the tuber. I had one tuber last year that measured over 1 foot long....a beautiful plant as well.

We use the 1/2 gal size but we don't put holes in the bottom as they don't get a lot of watering- none at all until they get about 6" tall & then minimal water until planted out -you just have to not get them too wet. We use the Moisture Retention Miracle Grow potting soil so there's very little watering done at all while they're in the milk cartons.

Would using the 1 gal. jug work as well? (with the tops cut off?) I was also thinking of using the large coffee tins? Would they work or would the metal do something to the plants?

We use the cardboard cartons because they are shallow & when you are starting the tubers you just lay them on their side on the soil then barely cover all but the eye end with soil. The eye end gets left out of the soil- so they're lying there with their heads out & their bottoms under about 1/4- 1/2" of soil. I think the plastic & the coffee cans would be too tall- you could cut the plastic ones down to about 4" though.