Rose.
I assume you have them inside in trays or pots of soil?
Once they are sprouted, or at least show a strong eye they can be buried in the soil. I use zip lock baggies instead of pots because they take up less room (and this year I am starting about 300 of the little suckers). Once they have eyed up, I put a little soil in the bottom of the zip locks, put in the tuber, and cover it. I don't zip the zip lock, but they usually fold over and are essentially closed. I check them every day or two, and when the sprout starts pushing up, I add more soil. I continue to add soil until the baggie is about 1/2 full, and they are buried a good 3". I then cuff down the sides of the zip locks so they stay open.
Once they are exposed, they need to be under lights. (until then light doesn't matter since they are buried.) I use standard fluorescent bulbs in a cheap 4 ft shop light fixture.
Soil needs to be moist, but not really wet during this whole process. With the baggies, until I cuff them open, I rarely need to add any more water, after that I use a pump sprayer, so that I don't over water. Baggies are great for that too, because its easy to pull the sides away and spray water down to the bottom, so you are not just moistening the top of the soil.
Once I have little 4-6" plants growing and I can see a decent root mass (again the baggies make this easy), I stop spraying and water more normally. I still have to be careful, as I don't have drain holes in the bottom. I feel safest just dipping a dixie cup into a bucket of water for each baggie, so I don't "slip" with the watering can and douse them.
When it is getting close to planting time (for me mid May - end of May) I move them out to my screened porch to start hardening off. Last year I screwed up and left them out there in the rain and drowned a few. It didn't kill the plants, but it did kill the fine roots, so that when I planted them they had a very hard time until they rooted out again. A couple never really recovered.
Hope that helps.
