Tiny SeedsDon't flood them!
Some perennial seeds, notably Calceolaria, Calluna, Campanula, Erica, Heuchera and Leontopodium (Edelweiss) are very small. It is easier for hand sowing to mix the seeds with very fine sand, or talcum powder, for more even distribution. Do not cover with soil. Instead, press the seeds very lightly. Irrigate from the bottom, or with a hand sprayer, so that the seeds will not be washed away.
For bigger hard-shelled seeds, like Acanthus, Lupins, Iris and Paeonia, mechanical scarifying of the shell is helpful for quicker swelling. One method is to grind the seed in dry sharp sand or sandpaper. They can also be treated for several hours in lukewarm water prior to sowing.