Autumn sowing of hardy annuals

As a trial I sowed Cornflower, Coreopsis, Pansies, Honeywort, Lavateria, Sweet pea and was so delighted that they have all germinated and since been potted on. They are still in situ in my cold greenhouse and look very healthy at the moment but how do I overwinter them. I have an option to use a poly tunnel with automatic watering system or should I just place them outside with some frost protection? As a novice gardener I would appreciate any advise. Thanks