Fill a seedling flat with a moist potting mix to within 1 inch of the rim. Sprinkle the carnation seeds on the soil surface thinly, sowing approximately two seeds per square inch.
Cover the seeds with a 1/8-inch layer of moist potting mix. Cover the top of the flat with a plastic bag.
Set the flat in a warm location. The seeds germinate within five to seven days.
Remove the bag and move the flat to a warm, sunny window. Water the soil when the surface becomes dry.
Transplant the miniature carnation seedlings to individual 3-inch diameter pots once they develop their second set of leaves. Fill the pot with moist soil. Lift the seedling from the flat by its top leaves and plant it in the new pot at the same depth it was growing at previously.
Move the carnations to a sunny, well-drained garden bed after frost danger has passed in spring and once the seedlings are at least 4 inches tall. Plant miniature carnations 8 to 12 inches apart from each other and from other nearby plants, setting them at the same depth they were at in their individual pots.
Water the miniature carnations every seven to 10 days, or often enough so the soil doesn't dry too quickly. Too much soil moisture causes carnations to suffer root rot.