The whole urea panic makes no sense to me... "urea free" fertilizer gets its nitrogen from ammonium nitrate. Free nitrate doesn't exist in nature, at least not where orchids grow. Ammonium nitrogen is, indeed, the most "available" form for plants. But they have to "process" the nitrate to get it to a reduced form they can use. The conventional wisdom is that because orchids don't live soil (soil organisms break down the urea to a form that plants can use) they don't have those organisms. But what do they get in nature? Rotting detritus, maybe with a bit of bird poop. All organic nitrogen. If orchids couldn't convert organic nitrogen to a useful form, they would not survive. (There are no little fairies flying around dispensing ammonium nitrate...) So this makes zero sense to me. No doubt minerals such as calcium and magnesium are also present in that "soup". Nature recycles!
I recall an early mentor, a very good orchid grower and delightful human being who is, alas, no longer with us, being asked what fertilizer he used. His reply, "Whatever is on sale at K-mart or Home Depot"... inevitably, loaded with urea. So much for that hypothesis.
---------- Post added at 07:19 PM ---------- Previous post was at 07:11 PM ----------
Quote:
Originally Posted by Brock
Orchid roots kind of grow from the base not the tip like hair.
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Wrong! You have it backwards. Roots grow from the tips. (Hair grows from a follicle, at the base, that's why you need a haircut now and then, cutting hair does not stop the growth) A new root has little green growing tips, as the root develops, the silver velamin (spongy coating) grows behind that growing area. That's why the ideal time to repot is just BEFORE the roots emerge. When roots are handled, some damage to the growing tips is inevitable (but you try to minimize it) If you catch it just as the roots emerge, if any get damaged there will be more coming along. Those tips have microscopic hairs, which will also grab the fresh medium... and adapt to it. If root tips (with those little hairs) are damaged, the root stops growing.
You will also read about people trimming orchid roots. When they do, those roots stop growing. Some orchids are such vigorous root machines that they make plenty of new ones. (It is done by some commercial growers to get Cymbidiums to fit into pots, and south Florida Vanda growers where they are being overrun. I NEVER cut healthy roots or even "maybe healthy" roots. My conditions don't lend themselves to such wild growth, and I'm also not a vendor who has manage their land as they turn over their stock. Not a long-term strategy)
Have you studied any chemistry???? There is no such thing as "free nitrogen ions". In fact, some plants have nodules containing bacteria that extract nitrogen from the air (turning it into organic nitrogen compounds) so plants can utilize it. Legumes come to mind. Farmers include them in their plantings to enrich the soil. Which has nothing to do with orchids... (In the presence of heat, like in an engine, N2 molecules in the air can be split apart, they immediately combine with oxygen in the air to make oxides of nitrogen - NOX - a major component of smog, that's why cars have catalytic converters to deal with the stuff)
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