I going to chime in here a bit.
NE Wisconsin
In the fall starting mid late October the semi evergreen, and full dormants start to die back.
The hard dormants will die back completely to the ground and stay that way until the snow melts of late March early April.
The S/E never completely die back all the way, showing some green even when frozen solid.
When they are buried under a foot of snow or more I don't know what is happening, but in years with little or no snow cover they will start growing anytime the weather warms above freezing for a few days, then a hard freeze will kill off new growth. I consider this wasted energy for the plant, and have started covering plants with shredded leaves wherever I can to minimize ground thaw and prevent this wasted energy loss.
Evergreens stay green right up to a hard freeze, and they attempt to grow at every opportunity.
They also look the worst come real spring and take the longest to recover.
I don't buy southern plants anymore unless I know someone else in a northern climate has had success with them first.
I found out the hard way that for some reason some evergreens do rather well up here, while others were given a death sentence as soon as I put them in the ground.
This also happen with a few of the S/E but not very often.
By mid late April my plants are starting to grow gangbusters, shrugging off overnight freezing temps with no problems, the S/E's look the best at this time as they started growing with the melting snows, the hard dormants all have short stub fans that will catch up in a few weeks, the evergreens look like a mess at this time with a few shoots poking out here and there, by June they will look as good as the others.
If I could, I would plant new arrivals late April because it's the start of our rainy season, but it's also the reason most can't be dug for shipping.
I start planting seedlings around the end of May, we are a week or so past last average frost date, and it's safe to plant tomatoes.
