this is the first full winter season for growing in a hoophouse (12x32). I have green and purple varieties of lettuces, cabbages, and brussels sprouts. in each case, the dark purple plants seem to be doing a bit better than their green leaved counterparts. So either the purple is better at photosynthesis in low winter light, or could it be the darker leaf color absorbs more solar heat, allowing just a bit more growing time at the margins of growing temperatures. thoughts and observations?