Zinnias and green beans can be direct planted outdoors but they both need it to be warm before you plant them, whether started indoors or out. In your zone, wait till the end of May to start outdoors. These seeds need warm soil.

There are websites that have lists of how many weeks before last frost (May 15 in your zone) plants should be started, or if you need to wait till after last frost. They are a big help. Also, the back of the seed packet often contains this info.