Hi, Utah - I've actually used spray-n-grown for quite a few years on houseplants. I have had tremendous results with that. Last year I used it in my perennial/annual flower gardens outside and again saw a huge improvement - larger plants, more flowers, etc. It affect some plants more than others.
I will contine using spray-n-grow for as long as I can get it. I love it!
Here are a few tips on it based on my experience.
-it seems to have more of an impact on flowering plants than non-flowering.
-it seems to have more of an impact on annuals vs. perennials although my roses were incredible last year.
-spray-n-grown is meant to be used on foliage only, doesn't help much with the roots, that's what the fertilizer is for, however I don't use their fertilizer, I use miracle grow.
-I only use it on my indoor plants during the spring/summer months. I've noticed it doesn't help much during the winter plus the plants need to be dormant then anyway.
Now, as far as orchids. I only used it on orchids for the first time last summer. Having stated above its impact on annuals vs. perennials, you can guess that I didn't see a HUGE improvement on my orchids. However, I did notice some improvement - larger leaves, more vigorous growth, etc. As for the orchid flowers, it seemed the same - slightly more flowers on each stalk.
Since I just started using it on my orchids this past summer, and stopped in the fall, I'm not ready to make a judgement on spray-n-grow's impact on orchids - it will probably take another season or two to be able to tell.
I would say it's definitely worth a try for you, especially if you have any flower gardens - I had more compliments on my flower beds last summer than ever before!!!
If you have any more questions, let me know!