Palm Tree Care in Winter in NE USA
I have 6 potted palm trees that did beautifully this summer here in New Jersey. This is the second winter I have had them. Last winter I kept them in a SE facing porch room (unheated) with an electric space heater on a timer. The room has temporary plexiglass panels over the screening to keep out the wind. In the spring once we passed frost, I took them outside. They took a while to show life/growth but did. What can I do better this winter? I don't have any other space to put them that would be better.
Palms need, in general, to stay in temps above 45F, so if you can keep your space at least that warm, that might help.
Also, adding more light might help. You might install some supplemental light in the form of fluorescents, maybe an inexpensive 2-tube fixture for each palm, with one cool white and one warm white in each , installed above each plant. This article has more information: https://www.gardeningknowhow.com/houseplants/hpgen/fluorescent-lighting-for-indoor-gardening.htm
Another important point is to reduce watering. Test the soil deep inside the pot - an electronic moisture meter works well. The soil should be allowed to reach the slightly damp stage, about halfway between dry and moist on the meter, a little closer to the dry side is best.