Fertilizing when in Bloom

[WeirdGuySeattle]

I've run plants for years with 0 fertilizer, and they do pretty well (given other things aren't screwing you up).
They grow better with fertilizer, but if worried about things, you can always cut back on fertilizing and not harm the plant.
I'd say if you have good city water (not too high TDS) - or are using RO or distilled or something, keep fertilizing. If your city water is sketchy, cut back.