Sorry about bringing this up again, but now I'm not at all sure if it's better to use up the remainder of my Dyna-Gro 7-7-7, or go right to the GH FloraMicro and FloraBloom regimen when the collection wakes up from it winter dormancy. Here are all the bloody details:
- 7-7-7 -- given the dilution rate of 1/2 tsp./gallon, I already know that 46 ppm N is broken down into 14 ppm Ammonium and 32 ppm Nitrate. Mo is 0.0009% -- if I have the math right, that's 3 parts-per-billion. (Don't know if it's relevant, but I just wanted to throw that number out there anyway.)
- GH FloraMicro -- to match the dilution I'm using for the 7-7-7, the dilution rate would be 3.5mL/gallon (and yes, I have graduated pipettes for that). The difference here -- 3 ppm Ammonium and 43 ppm Nitrate. Mo will be 0.0008% (2.6 ppb).
- CEC (or lack thereof) is obviously an important factor -- low in pumice and none in granite. From one of the PM conversations you and I had, I think you mentioned adding zeolite to my 60% pumice/40% granite gravel mix so it'll increase CEC. Even though we're talking about only 64 cacti, I'm way too busy with other things, so I'll have to make do with what I've already got. (Man, I need to retire! )
- Heat -- not a problem in my part of L.A. As I mentioned to ohugal, daytime highs in the spring are in the 75-85F range, summers generally in the 80s and 90s. Summertime heat waves take the daytime highs up to about 100-105F (even higher in rare instances), although they don't last for more than a week.
- You mentioned the importance of light levels in previous posts. I live about 10 miles east of the coast, and the marine layer effect tends to produce cloud cover known to us Angelenos as "June gloom" burning off in the late morning/early afternoon. Sometimes we get it, sometimes we don't, but there are more than a few bright sunny days in the spring. In the summer it's always hot and sunny. Prior to last year, I had the entire collection under 40% shade cloth, then I decided to turn my portable greenhouse from temporary (for the November-May rainy season) to permanent. Given the GH's translucent white UV-resistant material, I think this was a good move for a couple of reasons. First, the filtering evens out light levels to eliminate the harsh contrast between light and shadow as the sun moves across the sky -- something that used to kinda bother me when I relied on shade cloth. Second, it protects cacti that are vulnerable to sunscorch during heat waves. (Wish I thought about that a few years ago, and it brings up a story I'll save for anther day.) From the Huntington's desert greenhouse in Pasadena CA:
Those photos are a fairly accurate representation of the light levels in there. Although I can only go by general impression, the light levels in my portable GH are about the same. With that said, Pasadena does get hotter in summer.