Crepe myrtle/lycoris

These two plants are not native to the PNW but you do see crepe myrtle and it is beautiful to see color in a tree/shrub during the fall. However; they don't do exceptionally well here either, I have seen many a specimen that looks like it partially froze and dead wood in the plants. Do we get that much colder than places in the south where they grow? Is that why they don't do as well here?

The other lycoris, spider lilies, I have trade for bulbs here twice and have planted them and never have I ever had them even come up. What gives?

Just hoping someone knows better than I about these two plants.

I have Crepe Myrtle - they do well here (in my zone: 7b) if you site them in full sun in good, well drained soil. They are low maintenance & take well to pruning, too. Mine are shrubs - there are some varieties sold that are shorter & would work in a smaller garden.
I noted that mine came through this past winter without any damage whatsoever.
I grow Heleniums, Eremeris, Lilies, Crocosmia & Erysimum at the base of one, and no problems. The oldest plant is about 10 - 12 years old or so.
Lycoris - I have planted a number of times - did not do well so I decided to move on to something else. Don't know if the issue is a heat deficit or what?

I don't have any Crepe Myrtle, but sure would enjoy it. I've tried Lycoris as well, with nothing but failure so I gave up on it.

I guess my curious mind wants to understand why they(lycoris) don't do here in the PNW. It is consoling to know others have not had success either and it definitely a climate thing?