On January 25 2014, I blogged about moving my son’s houseplants from his place to mine at -20. I wondered at the time how they would fare after their (admittedly very short) exposure to such cold, dry air.
Well, 10 days later, all but one are doing fine. I even repotted two of them (they really needed it!), then repotted one of the two a second time after I accidentally knocked it over.
The one exception is a young Ficus elastica: one of those pots overcrowded with micro propagated cuttings that passes for a houseplant these days. It’s not that Ficus elastica is necessarily any less cold tolerant than the other houseplants, but it was the only plant that had not been fully covered. It was in a cloth bag with a few other plants, but being taller then they, its upper leaves stuck out into the cold. I estimate that it was only exposed to about 30 seconds of cold air (in two blasts, moving into the car, then out of the car into my house), but now you can see the youngest leaves have browned along the edges and even their surface is damaged: a sort of yellowish mottling that might under other circumstances look like thrips damage, but that I figure is damage to the outer layer of leaf cells: the cuticle.
My guess is that these leaves will probably die and possibly also the bud at the plant’s tip. If they don’t, I’ll probably cut them off. However, the lower leaves (the ones that were inside the bag) seem fine. I’m assuming the plant itself is essentially all right and that it will soon begin to recover from its ordeal.
So, take my word on this, only a few seconds cold can damage plants: wrap them well before you move them in cold weather!