When to fertilize with blooming fert?

[Ray]

This has turned into a really good discussion!

"Recycling" of nutrients, including transferring them from living tissue to newly-growing tissue when external supplies are deficient, is quite efficient with most, but not calcium. That's why a decent, constant supply is important when plants are actively growing.

Most tap water supplies have plenty, and it is possible to overdo it, so I think it's a good idea to have some idea of the chemistry of your water before adding more.

As to the nitrogen loading, I wasted many years thinking that "high nitrogen" was a matter of the fertilizer ratio, but as Roberta wisely stated, its the amount applied that counts. It is possible for example, to overdo nitrogen with a 3-15-10 formula (any formula containing N), yet by keeping my application concentration low, I do not do so with K-Lite, a 12-1-1 formulation.

Fertilizer is important, but not all THAT important. An orchid is about 95% water. Of that remaining 5%, about 95% is carbon, oxygen, and hydrogen, obtained from the air and water. Of that remaining 5%, about 80% is nitrogen from fertilizer and that remaining 1% constitutes all of the other nutrients, combined.

The upshot of that is that if you focus your attention on finding a way to grow your plants that allows them to be watered heavily and often without suffocating the roots, that will do more for them than anything else. Add a tiny amount of fertilizer, and they'll be very happy.