Mountain Mint Not Growing Past Seedling Stage

Received plants of mountain mint and they are doing well. Trying to grow mountain mint from seed in trays but can't get them to reach leaf stage. Is it possible to sow them directly into the ground? What is best method? Is there still time to do it now?

If you are losing your germinated seedlings you have some damp-off fungus in your soil and growing area. These tiny seedlings are especially tricky, because even leaving them bent over after watering will kill them. It would probably be best to water only from below.
You can still (August) direct seed outdoors, but it is easy to lose the seedlings to snails and slugs, dry conditions, rainstorms and the family pets! Cover the seedbed with evergreen boughs and be sure to water with the mister nozzle frequently.