Quote:
Originally Posted by Ray
Alvaro - at 100-125 ppm N, Rain Mix is contributing 118-147 ppm Ca. The 10 ppm contributed by your water supply is of no consequence.
Rick Lockwood and I studied a lot of data before getting K-Lite formulated, which is a derivative of the MSU formula. It is 12.9%N and 10%Ca, so when I feed @ 100 ppm N, that includes 78 ppm Ca. In my last home, I used RO water, so that was it. My tap water here contains about 50 ppm Ca, so I'm dosing mine as much as you, and have been doing so for 8 years without issue.
The standard recommendation for plants in general is roughly 50-75 ppm Ca, but we must understand that with terrestrial crops and their extremely fine roots, the plant takes up essentially 100% of the solutions applied. 1L applied = 50-75 mg Ca absorbed. Because of the media used, if any, and their limited root system, orchids are unable to extract anywhere near 100% of what is applied, so our application of a "stronger" concentration translates to compensation for the diminished uptake.
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Thanks a lot Ray. It's always a pleasure to get such good detailed responses from you! It's a relief to know I have been feeding them correctly.
It also makes total sense what you are saying about orchids not being able to take up most of the fertilizer we give them which is why I water like you recommend with every feeding and getting to those weekly 100-125 ppm instead of doing it once every 2 weeks for example. Right now to achieve that I use 0,5g per liter so I water twice a week and so far so good. I may experiment soon with using lava rock instead of bark for my Cattleyas so I may end up watering a bit more so I'll have to adjust a bit. Thanks once again!
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