flower boxes for fall/winter in zone 8b

I'm planting and maintaining the flower boxes in front of a doctor's office, at his request. At the present I'm slowly replacing the summer flowers/herbs with some that will hopefully make it through our mild winters. The boxes are under an overhang so are somewhat protected. So far I've planted nasturtiums. I've seeded some specialty kale, chard and mustard for leafy color and some herbs (parsley, I think). Nothing that I've seeded has come up. Just wondering if the soil is too hot for germination. Any ideas??

I had to look twice for where you were since you asking if the soil was too hot!