You can sow them now, you just have to keep them going through the winter, a cold frame would help, but last year I sowed Lupins about now & they were fine outside without protection & got off to a head start in the spring, It was a very mild winter though. Try soaking them overnight before sowing.

They need a period of cold to help them germinate. I tend to sow mine in November and leave them outside in a cold frame. Having said that I get lots of self sown ones every year.