I use 'Grow' from Dyna-Gro (rather than Foliage Pro) on ALL my container plantings, indoor or out, foliage only or flowering/fruiting. And I use it at half strength (1/2 tsp/gal).

To be precise, I dose all my containered maples and conifers with Osmocote at the beginning of the season and then supplement with the Grow periodically through the growing season but no more than once a month. And tht is primarily to supply any needed trace minerals, as the Osmocote covers pretty much everything else.