Hi Ina, ppm means parts per million... I personally don't like intensive fertilizing strategies, too hard with a plant that flourishes in our conditions anyway, many people get it slightly wrong because, such a recommended dose rate often fails to consider environmental circumstances.... Temperature, rainfall, soil acidity etc, so for example if you & someone in California & my self all used the same dose rate we would all have a different growth rate result.... With some species, you would also have to consider, that they may need seasonal fluctuations in mineral uptake to spark the flowering cycles.. Sometimes you may achieve a wonderful growth rate, by stringent fertilizing, but may sometimes reduce flowering rates too..... If you use the analogy of hydroponics, there you see plants growing at optimum rates but only if the chemicals are carefully measured to the ppm, even small fluctuations in chemical rates can be detrimental to the plants & crops can be quickly lost through under or over feeding over very short time periods..... Hope that helps Ina Steven On 27 February 2013 13:38, Ina Crossley <klazina1@gmail.com> wrote: > I was reading an article which was about scientific writings which > included Zephyranthies > > What does 150 > ppm N mean? I know that would be nitrogen, but how would one know that > quantity? > > Ina Crossley > Auckland New Zealand zone 10a > > _______________________________________________ > pbs mailing list > pbs@lists.ibiblio.org > http://pacificbulbsociety.org/list.php > http://pacificbulbsociety.org/pbswiki/ > -- Steven : ) Esk Queensland Australia Summer Zone 5 Winter Zone 10