If you are using seeds you should first buy small flower containers and potting soil /perlite mix , the perlite helps to keep the soil airated , so it does not get to firm, put the seed about a half inch to an inch into the soil , keep your containers indoors in a light fairly warm room , you should have no problem getting them to sprout, after the start to sprout keep them indoors until they are almost to big for the container, then take them outdoors and plant them, you should have no problem then.

It is hot for transplanting plants. Maybe not in the shade but it the sun. Get them in shade outside first to reduce the chance of shock.

Always water. It covers up for many problems. Miracle Grow is great but use Root Stimulator at first. Of course, good, deep, soil with lots of good humis is great with a layer of mulch.

In your zone you should be able to direct seed now and still get good results by late summer. After seeds sprout be sur to thin according to packet directions. Sunflowers will definitely do well and are so easy for excellent results. Actually all of the ones you have should do well for you, Just get them in the prepared soil and water.