It can be a love-hate relationship between me and lisianthus. I LOVE it as a cut flower. It seems to last forever in a vase, well beyond when other flowers fade. But it' a bear to start from seed.
It takes 12 weeks to get to be a decent size, but prior to planting, needs cold stratification and then optimum temperatures to germinate. This was my first year trying the seed-route. I planted 72 and completely failed, then tried a second tray of 72 and was rewarded with 22 miniature sprouts 4 weeks later. At 8 weeks, these 22 are about the size of my thumbnail. Therefore, I decided to augment my meager crop by purchase 36 plug-started plants from a local greenhouse (photo) These plugs from a supplier like Farmer Bailey or Easy-to-Grow were most likely started as seeds in January. You can see how, 14-16 weeks later, they are still relatively small but well on their way to make an upward move for flowering shoots in the July heat.
I've decided to plant my tiny seedlings and the greenhouse plugs in the ground April 29th this year. Lisianthus is cold tolerant so I'm not too concerned about frost at this point. We'll see how they do with fabric, 6" apart with a drip line and supportive netting. I love lisianthus when it blooms but whew - not an easy flower to get started. I think I'll just splurge for the plug trays next year.