Illia

Welcome!

In your zone, I really wouldn't be too worried. I've got an unheated not too well insulated greenhouse in zone 8, and my 5 foot Namwahs survived several freezes (P-Stem, not the leaves) without any added protection for a while. My best advice is to keep that stem wrapped nicely with insulation, don't worry about the leaves if it is a cold hardy cultivar. If you want more warmth without money sucking heating, my best advice is to look into passive solar heating. (heating via water and/or cement; use a solid north backing on the greenhosue, preferably white to reflect heat and light, and use black pickle barrels to fill with water so they soak heat during the day and release it at night)


Edited to add - I'd keep the leaves if I were you until they are burned from frost. If it's a cold hardy variety. Otherwise it doesn't matter. A freeze at some point will kill them regardless if it kills the entire plant or not, all you need to worry of is the main stem and its base/corm.