I am finding it impossible to grow Lemon Basil having tried for two years. I have no problem with Genovese.
This year I sowed in small cells on the windowsill, some seed germinated and got to 2 leaves but then stagnated. I have a 75w bulb above it. One seedling I transferred to my Hydroponic growing tank kept at 73°F with 375W of light and good nutrients and it also failed.
Is this known as particularly difficult to grow? or is it just me?
You are well organised but I find it easier to sow basil in April (indoors), when all varieties grow more or less well, especially if yu can give them some extra warmth, and are careful not to water their leaves too much.
Lemon basil shgould germinate similarly to Sweet or Genovese, but you may (inadvertently) have some old seed?