It's not really giving off any heat... [Because holding an actual lightbulb for an extended period of time would likely burn his palms.]

As long as they stay in here, they'll handle the cold better. That, or maybe I'd bring in the healthiest and you can keep them as sort of... insurance plants.

[Gokudera's just standing still, holding onto the ball of light and wondering if he can take his focus off. Probably not.]