There is always at least 1 6500 in my flower boxes. I don't overload the plants with it, but they get the spectrum, and my plants are constantly turned and rotated, so every part of the plants get some time with it each day.

Crap, sorry I didn't answer the question - I have nice, thick, sturdy stems - I've seen others have week and spindely plants, so I'd like to say yes, but this could be attributed to many variables. I've never flowered without full spectrum, but I've made several other mistakes!