On 11 Jan 2015, at 9:52, Peter Taggart wrote: > I have been told that hormone rooting powder should be bought > fresh, and is essentially GA. You have been badly misinformed. Rooting powder contains an auxin (often indole- acetic acid) that stimulates root development. Gibberelic acid (GA) is a different compound altogether. Wikipedia has articles on "auxin", "gibberelic acid", and "gibberellin" for those seeking further enlightenment. Generally speaking (and very, very broadly) auxins promote root growth and gibberellins promote vegetative growth. This is a gross simplification, but may indicate why it's important not to confuse the two. If you run into your "informant" again, Peter, do take the time to correct his or her misinformation. I used to know a guy who bred hybrid tea roses as a hobby. He used GA to improve germination, but his first tries failed. He then carefully traced back through the literature to the original source of the recommended concentration and discovered that the recommended concentration in subsequent publications was ten times the original. When he reduced the concentration of GA accordingly, success followed. These plant hormones are very powerful and you must avoid overdoses. Ordinary drugstore hydrogen peroxide (3%) is suitable for sterlization of seeds bearing diseases on the seed coat. Another friend repeatedly failed to germinate seeds of Linum flavum compactum, apparently due to some kind of fungus carried on the seedcoats. A short soak in hydrogen peroxide led to success. I do not know of hydrogen peroxide affects germination, but it apparently doesn't hurt it. Incidentally and PS: Please, people, do not casually abbreviate chemical names like "hydrogen peroxide" to "peroxide". There are many different peroxides and only one of them is under discussion. Also be careful about spelling: it's peroxide, not paroxide. If you don't know how to spell a word, Google is your friend. -- Rodger Whitlock Victoria, British Columbia, Canada Z. 7-8, cool Mediterranean climate