"Bloom booster" formulas do not increase blooms as they claim. Plants use nutrients in a specific ratio, and phosphorus (the middle number) is always the smallest. Using a high phosphorus formula will just create a surplus of phosphorus that the plant cannot use.

The increase in light and nutrients is probably what caused your new spike. I would stick with a more appropriate fertilizer (I use a 3:1:2 ratio, but even a common 1:1:1 ratio will work alright), and keep giving them sun from that south window.

sounds reasonable. thanks for the advice!

You might consider a fertilizer lower in nitrogen, as nitrogen tells the plant to grow leaves, not flowers.

You can go back to the higher nitrogen after blooming is done.

What brand fertilizers do you use? I have used Dyna-Gro Grow and Bloom forula for years, today I decided that I would like to try the Dyna-Gro Orchidformula and ordered it from Calwest Tropical.

I have been pretty happy with my results with Dyna-Gro.

I swear by Dyna-Gro fertilizers and use both Grow and Bloom and have also used them for years. Tried others, like MSU, but always switched back. To my fertilizer regime monthly I add liquid seaweed, magnesium, and Dyna Gro Protekt. Every once in a while during the main growing season once or twice I use something else for a little zing, like Miracle Gro or Better Grow or whatever suits my fancy.