I am not sure if there is a trick to it. Basil has always grown well for me. I think it knows how much I love it...

It does seem to like alot of water though. In soil I always but basil in a pot with a water reservoir...and now this aerogarden is all water with no soil, just a peat pod to start them. We do use filtered water or rain water for the plants too...no straight tap water.