As an experiment I brought in a pot of them over the 2007-2008 winter here in Illinois. They did well under T5 High Output lights. They flowered in January 2008 and then again throughout the Summer 2008 outside. I didn't bring them in this winter and are now gone to flower heaven. I'm not sure how long they would go if I kept them up.

I have been able to keep window boxes of impatients full of flowers and very happy in a low light SE window for the past 2 winters. They were recently cut back a bit but are in full bloom now. I will put them out this summer and try again next winter. I would think they would be fine under the lights.

I usually start my impatien seedlings under florescent lights during the first week in March for translating outdoors around Mother's Day. No problems at all.

Additionally, I usually take cutting of new guinea impatiens before first frost in late October and keep them under lights until the following May. They flower the entire time under cool white florescent bulbs.

hummer_girl: I don't know if impatiens react negatively to that much light!

That doesn't sound like too much light at all!

Happy Growing,
Rokal