Both puplications of Xavier have the merit to have collected in two articles all which it is necessary to know to well cultivate orchids. It is preferable not to have to look here and there for the informations.Well, quite interesting, but there are some things that are only suppositions (about MSU formula for example). And to tell the truth, I have to see his plants grown for years before I can say "thank you for your cultural advises". there's nothing new for me by the way...
the flasking methode is interesting! thank you for that!
A little bit Paul.there's nothing new for me by the way...
Absolutely, because I have seen only few cases of true toxicity, proven by leaf analysis, which would mean the analysis result exceed the norms. So far sodium, boron, manganese ( in one US bark source) come to mind.A little bit Paul.
A bit later it says that toxicity is not an issue (with relation to potting mixes/feeding), apparently not feeling that nutrients can cause "toxicity" by definition.
I have on hand the analysis of quite a lot of growers, some pristine ones for even pot plant phalaenopsis, and so far there has never been any potassium toxicity ever reported, in terms of quantity in the analysis. So for me, potassium toxicity might exist possibly, but it has never been found, and in fact for the low K fertilizer, that would be interesting to have true foliar analysis, etc... to see if there is really a potassium toxicity problem, which would be unheard of.He mentions the low K feeding as a US phenomena, but really doesn't get the reasoning correct. He neither critiques it as significant or not.
Not at all a low K system in fact, I use the tank mix once every 3 months, so once every 50 waterings, it's negligible. It is not a low k formulation, but the combination of those three is required to supplement boron without any local phytotoxicity risk, the calcium + boron is safe on the new tender growth, and the ammonium nitrate is there to avoid a pH increase from the calcium nitrate. It is a proven way to supplement boron safely.Then his new feeding regime is a hybrid of his old (high K feeding) and a new low K system. "Every 3 months I use a simple tank mix of 300mg of calcium nitrate and 200mg ammonium nitrate, with 5mg of boric acid as a drench". Although he insists its not to get any more calcium and less potassium into the plants.
I do not like a lot of urea and ammonium, but the plant do. If you ask Floricultura ( and they have plants that are 20-30 years old, motherplants, including quite a lot of species...), they still like it. The phals growers, all the successful ones use ammonium and urea ( and none is using the MSU).He still likes a lot of urea/ammonia, and is heavily invested in a calcium/boron theory (micronutrients in general). (although I will agree that calcium metabolism in virtually all organisms is partially linked to boron). Given some of the high alkalinity waters available to his growing conditions it could work for him.
For the pH, 5.7 to 6.8 could be way too much for some species. In fact, we do not know the perfect specifics of all individual orchid species, but things like pansies, pelargonium, etc... have a pH range that is very narrow ( around 0.2 to 0.3 unit, not more), therefore my recommendation.From my experience in growing plants over the years, and apart from some of Xavier's more ''unusual references'', I would agree with most of what he says. Except the pH quote of 5.7-6 is a bit narrow to me. I would say 5.7 to 6.8 would be quite workable for most species. I also agree with the 50/50 nitrate/ammonium N for orchids if not all plants when specific species data is unavailable.
How long would you be scared? I'm up to 2 years of this system on some very big plants (multiple genera). No losses and they keep getting bigger.:wink:I would be more scared by a potassium deficiency, because it is a sudden collapse of the plant, and once the potassium is moved out of the old tissues, there is no way to restore older plant parts content when they are too old ( 2-3 years old), which means one could loose many old bulbs at once.