Moisture IS important for germination BUT also soil temp so if keept cool & alowed to dry should not have a problem.

Do all you can to get the bombs to dry very quickly. Keep your mix as dry as possible while still wet enough to form into the balls. Keep the size small for quick drying, no bigger than the diameter of a quarter....smaller yet is fine, too. Spread them out with a lot of space around them to speed drying time. Dry them in an area with low humidity, again to make drying go quickly. Summer air conditioned areas are good and so are heated winter areas if your outdoor areas are humid like mine usually are. Run a fan to increase air flow and speed drying, too.

If your wedding is a ways in the future, you can make up a few, dry them, and let them sit for a few weeks. Then break them up, and plant them, and see if they are duds. With quick drying, I think you will be okay.

Or, you could make some pretty envelopes and give seed selections.

Hi Leah,
I would think ordinary potters clay could be rolled in seeds and have them stick without further wetting? I'm with you that wetting might mildew the seed, etc.
why not dispense with all the dirt stuff and just tie up the dry seed mix in traditional chiffon like you would rice? If the seed is too small, any material you chose would do. or if you want something people just have to add water to, just include a lite seed starting mix.