Orchids looking ok but will they flower?

[Ray]

Originally Posted by Connie Star

To my eye most of them look a little small to start blooming. There are also "bloom booster" fertilizers that might help, but as has been said, temperature is key.

Bloom booster fertilizers don't boost anything.

The first commercially-made mineral-based orchid fertilizer was Miracle Grow 30-10-10, developed by Dr. O Wesley Davidson of Rutgers University. (Cut-flower orchid growers were centered in NJ and Long Island after WWII, having been moved there from England to avoid the Blitz). It was heavily applied and the plants grew great. However, after a while, growers started noticing a reduction in flower production, due to the overapplication of nitrogen.

They formulated another blend adding cheap phosphorus compounds to dilute the nitrogen content, and courtesy of a little marketing, the "bloom booster" was born.

it doesn't "boost" anything, but if you've been over applying nitrogen, stopping and switching to it "allows" the plant to bloom normally.

[Connie Star]

I knew that "bloom boosters" were basically higher in phosphates and lower in nitrogen. What if you just didn't use as much fertilizer, to avoid the nitrogen?

[Roberta]

Originally Posted by Connie Star

I knew that "bloom boosters" were basically higher in phosphates and lower in nitrogen. What if you just didn't use as much fertilizer, to avoid the nitrogen?

That's what I do... when plants aren't growing much, they don't need as much fertilizer. And when the weather is cold and nasty I'm not as likely to go outside and fertilize anyway. So my level of motivation and the plants' needs coincide nicely.

[Connie Star]

I take it you grow your orchids outside? I live in Massachusetts so they only go out in the summer.

[Ray]

Originally Posted by Connie Star

I knew that "bloom boosters" were basically higher in phosphates and lower in nitrogen. What if you just didn't use as much fertilizer, to avoid the nitrogen?

Yes - it's the mass of nitrogen applied per unit time that's important, not the ratio of the elements in the fertilizer.

I used to think that a more "balanced" fertilizer - 10-10-10 or even 7-9-5, for example - was better than a "Mir-Acid type" at 30-10-10 to avoid overdosing the nitrogen, but after learning to use the nitrogen content as my control factor (as do professional nurserymen) and more about what orchids receive in nature, I've gone to an even more "imbalanced" K-Lite formula at 12-1-1, and used at 75-100 ppm N applied over the course of a week, I find my plants to be doing great.

[Roberta]

Originally Posted by Connie Star

I take it you grow your orchids outside? I live in Massachusetts so they only go out in the summer.

True. But that pattern just gives me the function of "less fertilizer in winter when they don't need it". Growing indoors, if light is less, growth will also slow down. But in general, I think you can just cut back fertilizer concentration and frequency. Ray is spot-on to "follow the nitrogen". That seems to be the primary nutrient of the major ones that orchids actually use, and they use it to grow new tissue. So less growth, less nitrogen and the blooming part takes care of itself.