It depends on the plant. I think most of the annuals you mentioned would bloom even under 24 hours of constant light. Try setting the lights at 18on/6off and see from there. If they don't bloom, cut the lights to 12/12. Early spring flowers will bloom under lots of light, but fall blooming plants need that 12hrs of darkeness since it simulates fall.

Not that you asked, but, you might have a problem with sunburn when you move HPS grown plants outdoors. I have experienced this with regular HPS, presumably because of lack of blue and violet light that cause plants to synthesize pigments that protect them from ultraviolet. Maybe, your Hortilux bulb has enough blue to mitigate this problem or, maybe, it doesn't. MH grown plants typically don't have a sunburn problem.

Thank you stacysgreenhouse. I appreciate the input and I will do as you suggested. I would have never thought to do 18 hours, so again, thank you.

Thank you struwwelpeter. The reason I spent the extra money for the 1000 watt hortilux was to get the blue -- from the limited knowledge I have, I need the HPS for the plants to flower. I'll let you know if they sunburn -- I'll try putting them in the shade and slowly moving them into the sun a little at at time.