Easy. Set up a bank of a half dozen 40 watt flourescent bulbs with mirror reflectors and gro bulbs and timer for long days.You could in fact grow them forever this way as you harvest seed and sow and restart the whole growth cycle year round. I doubt the seed need any rest period if you provide the light,soil, and water -their off... Would be fun.

In 7b you might want to spring for snapdragon plants which will bloom most of fall and early winter. Enjoy the color. Violas also although the deer and cottontails make short work of those as they browse. Ken makes an excellent point regarding the 'vermin'. They, plus the scavenging birds of winter will eat much of what you thought you sowed or disturb the soil so the seeds fall deeper than intended and never come up. Guess that's why Mother Nature has flowers making so many seeds.

Annual poppies - the peony/opium type, Shirley poppies, California poppies, etc. - all germinate very rapidly from seed and it is still not too late to try again.

If you are here in Oklahoma, I've had the best luck with Oriental and corn poppies and the like by broadcast sowing the seeds on the soil surface in fall or winter---any time from November to February. They need daylight to germinate, so don't cover them. They'll germinate in winter or spring and you'll have blooms from mid-Spring through around the end of June, depending on the weather and also depending on how far north in the state you are. I'm very far south in OK, so our poppies finish up here as soon as it gets hot, which usually is June but sometimes late May. For California poppies, I've had success with them by broadcast sowing them on the soil surface in earliest spring. They really need sandy soil though, so if you don't have that, they will struggle.