No Maura, K boosts flower no, quality and longevity. For bloom booster fertilizers are high in K and P. For SH I recommend 125 ppm of NPK each i.e. the water solution you use should have 125 mg/l of all NPK along with Ca and Mg (Most probably supplied through the water already). Superthrive would be good as a spray, once every week or so, but I would not grow plants in a media with constant supply of enhancers like hormones and vitamins that are found in Superthrive.