sooby said:There are various different acids that commercial growers use to lower the pH of alkaline irrigation water, but the reason I suggested vinegar in the other thread is that it is often already in the house or is at least easy to get from a supermarket so more convenient for a small test. That (the teaspoon of vinegar to a litre of irrigation water) was really just for an initial trial on a plant or two to see if they would respond by producing greener new leaves than the untreated ones.
Sue,
I initially started acidifying my water with vinegar, with good results, but a few months later I was advised by an organic chemist/horticulturist that acetates are a vinegar by-product, and could promote rot by encouraging the growth of harmful soil microbes. Since I grow a lot of plants (South African bulbs and cycads) that have their share of problems with root rot, I switched to anhydrous citric acid which I found on Ebay. Because of its concentration, it actually worked out to be far more economical than vinegar. (I also read that sulfuric acid is a popular water treatment used by professional growers) A drawback of the more concentrated acids is that mixing small batches becomes more difficult, if not impractical, due to the precision required.
If the soil chemistry will tolerate it, horticultural sulfur in the form of a product such as GreenAll F.S.T. will work wonders. It also contains iron, manganese and zinc.
http://www.ebstone.org/product...
I didn't have a pH test kit at the time, so F.S.T. was the first remedy I tried after reading an article in the Cactus & Succulent Journal about the harmful effects of alkaline water. The results were impressive. At that point I had a wide variety of container-grown plants which had essentially "stalled", despite regular watering and fertilization. Within two weeks after applying F.S.T. there were daylily scapes and new, healthy green leaves everywhere, despite the fact that we were in the doldrums of mid-August. Cycads which had been sulking and surviving with old leaves for at least a year were flushing luxuriantly, stressed cactus & succulents greened up, palm trees jumped back into growth—everything looked amazing. Even though it worked so well, I'd only recommend F.S.T. for yearly application, because of the extra elements it contains.
The C&S article said that the newly-acidic conditions would release the bound-up fertilizers in the soil. It also said that with proper water/soil pH balance, fertilizer applications could be halved. Both of these things appear to be true.
Results with field-grown plants were also positive, only not as dramatic. I think this might be because of the mass and buffering ability of "the earth" as opposed to the captive, artificial and relatively "dead" environment of a pot. I can always tell when one of my container plants has managed to poke a root or two into the ground below - the difference in growth and general appearance is significant.
Ken
