I have some trident maple seedlings all the leaves have dropped except the ones at the top, that is the new growth. They are orange in color, but won’t pull off easily as the other older leaves. Is this something I have to worry about, they are in my unheated greenhouse, right now it’s in low 30s in central Illinois and next week is supposed to be in the 40s-50s. Is there anything I need to do, except watch them die?