hi i have a 24 small cell insert. probably an inch across. how many petunia seeds should i sow in each cell insert
I'd say that it depends on the variety. For many of the choicer varieties you don't get many seeds in a packet, perhaps only 12. In that case I'd only put 1 or 2 seeds per cell. For other varieties you may get a hundred or so seeds in a packet, in which case you can be more generous.
Petunia seeds are very tiny so it usually says "sow thinly" on the packet, so unless you want to fiddle about, just take a very small pinch and sprinkle carefully onto the surface. I sow them into moist compost in a seed tray. Don't cover them. They will need some warmth and they don't like being watered with cold water, so let the water get to room temperature. Use a fine rose or sit in a tray of water to water them, but don't let them gat too damp of they can "damp off". When they come up they can be thinned out or when they are big enough to handle prick them out into small pots with fresh compost. Keep frost free.