That should not be an issue at all. they are biennieal. Sow a mere 1/8" and 1/2" apart, dust with soil, mist with water and germinates in 6-10 days. Keep them moist and plant in direct sunlight if you are concerned about the temperature. The only issue would be frost and I think you have quite a while before that is an issue and they are long blooming. After they are through blooming for the summer cover the area gently with burlap or some kind of mulch that will protect from the winter; they should come back next year. I planted a cpl seeds in spots around the flower garden because they tend to spread out and will spread out taking over the garden, FYI