Another difference with rainfall is the way it falls: gently and slowly penetrating. Some sprinkler designs can mimic this but not very well. Soil that is truly soaked well holds water longer, with obvious benefits to the plants. Possibly the answer is a combination of water quality, application and other conditions. I've talked with other growers who have had the same experience. On 26 October 2012 11:10, Paul Licht <plicht@berkeley.edu> wrote: > Hannon > Why is rain water different from hose. Here in Berkeley, we found that > the domestic (hose) water comes at about pH 8.9-9.2 whereas rain is much > more neutral. We know this has a big effect on cacti and probably on > lots of other things. > > Paul Licht, Director > Univ. California Botanical Garden > 200 Centennial Drive > Berkeley, CA 94720 > (510)-643-8999 > http://botanicalgarden.berkeley.edu/ > > On 10/26/2012 10:43 AM, Hannon wrote: > > As Leo notes, a summer dormant (leafless) bulb having perennial roots, > such > > as various Massonia, Albuca and especially amaryllids, can utilize water > > that comes along during dormancy, at least in theory. Are bulbs with > roots > > growing upward and extending above the bulb positioned to take advantage > of > > the first rains, or to obtain a little water from a summer shower? > Perhaps > > both? Plants without perennial roots (many corms, narcissus, etc.) are > not > > benefited by water they cannot absorb and may be harmed if conditions are > > favorable to pathogens. The other main fear in watering off-season is > > starting plants into growth before their time-- days too long, temps > > overall too warm, etc. > > > > Cool night temps are critical for the growth of Mediterranean geophytes > in > > autumn through spring and during an otherwise hot or warm dry dormancy > > the often nights remain cool also (<70F) . Warm and humid ambient > > conditions during this period can be fatal for these plants with or > without > > any supplemental watering. Watering should not be performed to "cool the > > roots" unless a plant is in growth. Storage location and insulation by > soil > > mix are the best protection from heat and dryness. > > > > California has the driest, hottest conditions on average than any of the > > Med climate areas. South Africa's Western Cape, by contrast, receives > scant > > rainfall in summer: at least 0.5" ppt in any given month (Los Angeles = > > four months with 0.0 or barely more ppt). I keep all my bulbs completely > > dry over summer with a few exceptions for plants that keep some green > > parts. We get over 100F about 10 days/year but night stay cool, usually > in > > the 60s night minimum all summer. > > > > In my experience there is a big difference between rainfall and water > from > > the hose. It is easy to overwater and kill plants by watering too > > generously with the hose, even with good water, but an even greater > amount > > of rainwater at the same time of year will not harm the same plants. Does > > anyone have an explanation for this discrepancy? > > > > Dylan Hannon > > > > On 25 October 2012 21:51, Leo A. Martin <leo@possi.org> wrote: > > > >> Some of us have watered our southern African bulbs during the summer on > >> purpose or through carelessness and have not had problems. The Great > >> Karroo areas can get some summer rain, which generally comes from the > >> northeast but doesn't reach the south coast of Africa, in contrast to > the > >> winter rain, which generally comes from the southwest and doesn't reach > >> too far inland. The Karroo area is in the overlap. > >> > >> I have noticed especially Albuca and Ornithogalum seem not to mind water > >> when it's hot. Albuca clanwilliamgloria seedlings began sprouting here > >> several weeks ago in a large container I left out all summer, exposed to > >> some rain and a garden hose that didn't pay attention. > >> > >> But realize that some winter-growing plants may die if watered even once > >> during hot weather. Lachenalia comes to mind. So if I were perfect I > would > >> not water most of my southern African, winter-growing, deciduous-rooted > >> bulbs in the summer. > >> > >> The fleshy-rooted Amaryllidaceae are another situation. Their roots stay > >> fleshy all year and, even during long warm summers, don't wither deep in > >> the ground. These plants struggle in my care unless I manage to keep > their > >> roots alive during their long dormancy, especially first-year seedlings. > >> > >> Leo Martin > >> Phoenix Arizona USA > >> > >> _______________________________________________ > >> pbs mailing list > >> pbs@lists.ibiblio.org > >> http://pacificbulbsociety.org/list.php > >> http://pacificbulbsociety.org/pbswiki/ > >> > > _______________________________________________ > > pbs mailing list > > pbs@lists.ibiblio.org > > http://pacificbulbsociety.org/list.php > > http://pacificbulbsociety.org/pbswiki/ > > > > _______________________________________________ > pbs mailing list > pbs@lists.ibiblio.org > http://pacificbulbsociety.org/list.php > http://pacificbulbsociety.org/pbswiki/ >