The zinnias are sprouting! We planted zinnias and carrots on May 5, and when we came in on May 9, we found these little zinnia sprouts.
So far, we've watered them a little every other day because the Mars Regolith Simulant seems to dry out quickly. Both carrots and zinnias like full sun, so we have them in the window at the front of the shop which faces southeast. It gets pretty warm there when the sun is out, so that probably contributes to the MRS drying out.
Hopefully the carrots will sprout soon, too!