Fertilizer mixing criteria during seasons

[Ray]

I am a big proponent of looking at what is happening to plants dealing with Mother Nature....

Epiphytic orchids get fed when it rains, and that consists of the dust, animal droppings, and exudates washed down from the canopy above. In general, analyses of such "throughfall" and "trunk flow" tend to be frequent, VERY dilute (max of 15-25 ppm total dissolved solids), quite consistent year-round, and almost all nitrogen.

Also, if you look at the chemical makeup of an orchid, outside of the 95% of it that's water, 95% of the remainder is carbon, oxygen, hydrogen and nitrogen. The first three come from air and water, the N is from fertilizer.

That tells me that changing formulas isn't necessary or even beneficial, that I should feed frequently and dilutely, and that nitrogen management isn't a matter of fertilizer formula ratios, but of concentration. I have used K-Lite (12-1-1-10 Ca-3Mg) consistently for 5 years now at about 25 ppm N, and have seen nothing but tremendous growth and flowering.

You can overdo the nitrogen with the 5-15-30 by overusing it, or you cannot do so with the 30-30-30 by controlling your application.

You are correct that a plant in active growth will need more fertilizer than it will when paused, building up stores, but even then the demand is not all that much; in order to gain one pound of mass (a lot for most orchids), it must absorb and process about 25 gallons of water, but only about a teaspoon of NPK fertilizer ingredients.

I'll get off of my soapbox after one, final comment: fertilizer is probably the least important of all orchid culture parameters. Focus on the others, and periodically give them "some" food, and they'll perform well for you. Feeding NEVER compensates for failings in other areas.