storing winter-growing bulbs during dormancy

Paul Licht
Fri, 26 Oct 2012 11:10:09 PDT
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

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 <> 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
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