DORMANT TEMPERATURES

Good point Jane. I had meant to include my location, which is Carnation,
WA, quite a bit east of Seattle and against the foothills of the Cascade
mountains, where we receive about 50 inches/year—30% more than Seattle
(forecast calls for 4 inches of rain over the next three days, for
instance, and thats not particularly unusual this time of year)—and the
humidity is quite high even during the warm summer months. I have lost
plants to moisture-related decay (for example, a pot of alstroemeria
seedlings) even against that south wall after having received no direct
moisture for months. An empty 1-gallon pot of soil left out in the open on
my property would almost never completely dry out.

On the other hand, the only bulbs I put against that wall are from climates
that are significantly hotter and drier than mine (e.g. lowland/inland
South Africa and California). Also, relating to your point about bulbs
growing deep in the soil where temps are moderated, I do pack the pots
tightly together in deep trays so that they are buffered somewhat from the
baking effect of the direct sunlight.

On Thu, Dec 19, 2019 at 12:21 PM Jane McGary <janemcgary@earthlink.net>
wrote:

When we discuss how we grow certain bulbs, I think it's necessary to
mention where we live. Cody, who posted recently, lives in a suburb of
Seattle, Washington, where it may be safe to keep dormant bulbs "against
a sunny south-facing wall," unwatered and with at least 15 days of high
temperatures in summer. I live a couple of hundred miles south of him,
near Portland, Oregon, and I'd kill a lot of bulbs if I did that in
summer. Portland is in an inland valley, east of the Coast Ranges and
west of the Cascade Range, and has more sun and lower humidity than
Seattle in summer. If you live in California, don't do that at all,
please. British gardening books often recommend "summer baking" for
potted geophytes, but we have to consider the climate differences where
the author is living (some parts of the British Isles get much more sun
than others, and/or greater summer humidity). I mention humidity, rather
than just rainfall, because it can affect soil moisture in pots.
Remember, too, that many (though not all) dryland geophytes keep their
bulbs deep in the soil, where temperature and to some extent moisture
are moderated.

I manage soil moisture for dormant bulbs by keeping them plunged in sand
and covered against rain. Half my collection is sprinkled lightly a few
times during the dormant period, and half is not, depending on (1)
whether the bulbs are in pots or directly in a raised bed, and (2) the
climatic conditions they have adapted to in nature. The pots I use are
either terra-cotta or plastic mesh (used for hydroponic and aquatic
growing), not solid plastic.

Some bulbs seem to break into growth in response to temperature, and
others more to moisture. Some may just be "timed." This year we had
significant rainfall in September, which is unusual, and some fall
crocuses flowered a month or more earlier than they did in the roofed
bulb house.

Jane McGary, Portland, Oregon, USA

On 12/19/2019 11:50 AM, Cody H wrote:

This year I put my summer dormant bulbs (both South African and
Californian) in their pots against a sunny south-facing wall, where temps
probably break 100F at least 15 days during the summer. In that location,
they receive no rain, and I didn’t water them at all, even the

(relatively

few) amaryllids. I just repotted them all and most are looking very
good—healthy roots and not dessicated, and many are beginning to grow.

The year before I kept them in the basement, where the temp rarely hits
75F, and although the bulbs looked fine when I reported them that fall,
many of them failed to break dormancy that winter and I lost quite a few

rot. I will be putting them against that south facing wall again this
summer!

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