JoeReal

PhilMusa: As long as your basement is a few degrees above freezing and you don't water, you don't need to take out the leaves. That's what I do every winter for my cold sensitive plants. I just haul them in. I clean only the dead and yellow leaves. I keep them in the dark. Sometimes when the temperature gets too high, like about 13 deg C (> 55 deg F) or more (it happens in my garage), then I turn on the bright CF lights for a few hours, water sparingly if the pot becomes really dry. This keeps their leaves green. Most tropical plants become inactive when temperature falls below 55 deg F, that is my guideline when to flip the switch on inside the unheated garage. So if you have a greenhouse, that would be a nice guideline too.

The way most tropical plants gets damaged during the onset of the colder months is due to chilling injury. The chilling injury occurs when temperature is cold (different plants have different temperature tolerances) in the presence of strong PAR (Photosynthetically Active Region) lights. When the leaves get hit by these lights, electrons in the chloroplasts gets energized, but the rest of the photosynthetic appratus is still asleep (metabolically inactive) due to cold temperature. The energized electrons with nowhere to go will damage the surrounding tissues when it dissipates its energy. So it is better to keep it dark when it is cold. You can see the injury similar to bleached or burnt leaf, because they literally burn from the inside. And we are talking about above freezing temperature here.

Below the chilling injury when it gets colder still is the freezing injury. Freezing injury is of course debilitating when temperature gets below freezing point. Ice crystals simply damaged the tissues physically. Freezing can be caused by frosts or simply cold freezing air temperature. Banana freezes below 0 deg C (32 deg F) by a few degrees (4-8 deg F below pure water) due to the solutes in their sap. Drier bananas will survive much lower freezing temperature than the wet succulent ones because their solute gets concentrated when they're drier.