I'm fortunate to live in a zone where I don't have to container grow my bananas, but do have to occasionally wrap them in blankets when we have a freeze. The three bananas you are asking about are not cold tolerant bananas at all and would not make it in the ground here in coastal Louisiana. I would imagine that they are in stress now due to being indoors. None of those 3 like temps in the 40's, much less the 30's. With the crazy weather we are having, I would wait until night time temps get closer to 50.

Steve

" Is it too early to bring these outside?"

Yes.

Based on my experience in zone 5, Chicago area: To maximize growth, if you keep them in pots, take them outside in late May, and, if you plant them in the ground, do it in late June. This is because the meristem (growing point) is below the soil surface and the ground temperature lags the average air temperature by about a month. If planted in the ground in May, the plants will survive but barely grow until about the middle of July, but, for the same reason, you will get a lot of growth in September and early October (because the ground is still warm).

If you keep them in pots, a trick is to water them only with warm (about 100 deg. F.) water to encourage growth. Also, it is better to use black pots exposed to sunshine to keep the meristems warm while the air is cool. Using these tricks, early May might work well for you.