Last year was the first time I'd ever grown lobelia, so I just plopped it down where I had an open spot in our front garden and hoped for the best. SO lovely! It is just starting to come into bloom now as you can see, and will get much taller (up to 4'!), so is really proving to be a worthwhile addition to the part sun area of the garden that's been such an unusual challenge to fill here in the city. It's also fantastic as a true summer flower - especially since our hulking mallow and rockrose shrubs nearby are on the tail end of their blooming as we near August.
Note: It does die back almost to the ground in winter, so I'd recommend putting a stake or something at the end of the season so you don't forget it's there ! (I didn't do that with the nicotiana plant in our side yard and planted a Columbine there and they are now competing for space, grr...). Also, Gardenia says it likes "moisture retentive soil" so the fact that it was originally planted under burlap bags and mulch is a very good thing!