The link or whatever it's called has disappeared so I'll just say what I do. Round about now I pot up the tubers in pots or trays using general purpose compost Leaving the crown uncovered. Water them but don't soak the compost. I have a cold greenhouse but have used a warm windowsill. After a few weeks the shoots appear . When they are about 3 inches tall I use a craft knife and cut them off the tuber including a tiny bit of tuber if I can or you can cut just below a pair of leaves. I use either 3 inch pots singly or maybe 3 in a slightly larger pot. For compost I use general purpose but mixed with grit or perlite. I've discovered they need well drained compost or they rot. Place the cutting into the compost and water to moisten then put pot into polythene bag not forgetting a label. They should be kept just moist and root quite quickly in my experience. Pot on when you see roots. The original tuber will re sprout and can be planted out when there are no more frosts.
Do you have a warm place you can put them? If so, I would pot them up into largish pots of a good compost with a little added extra fertiliser. Then water and keep in a warm frost free place. If you do not have a frost free place, Wait a bit before planting out.
i have never planted dahlias before. I would appreciate any help I can get and it will be greatly appreciated. I just bought few tubers. Some are all attached to the main stoke and some are separated. If I separate few more and plant them in the tray on my kitchen windowsill will they grow? Thank you.