Cyclamen hardiness - recent posting to Alpine-L of relevance to PBS so posted here

John Lonsdale
Tue, 08 Feb 2005 10:30:16 PST
We are slowly recovering from the recent cold spell and after nearly 2 ½
weeks the snow has receded from 75% of the garden.  It is interesting to
note the condition of some of the plants that were growing or appearing
before the snow and cold blast came, some encouraged by the previous
unseasonably warm weather into rather early growth, others behaving
normally.  Temperatures without snow got down into the single digits
Fahrenheit; after the 12” of snow came, the coldest part of the garden got
as low as 2F.  However my wireless sensor under the snow never registered
lower than 26F or higher than 31F.  

Various Adonis amurensis cultivars emerged as if nothing had happened, as
did the first Crocus biflorus.  Eranthis pinnatifida and a few other
eranthis have woken up and are emerging, even though their raised beds are
still solid ice an inch or two inches down.  The wintergreen Fritillaria
davidii is unmarked apart from a few minor scorches, F. thunbergii was
emerging in several places and they are all OK; most of the early snowdrops
are just fine, some flowers on one of the elwesii clumps that were up but
unopened have keeled over irreversibly but others on the same clump are OK.
The Florida panhandle Trillium underwoodii and SW Georgia Trillium decipiens
were deliberately buried under 6” of chopped leaves and are just fine – some
had completely unfurled leaves.  Protection from rapid thawing and
desiccating wind seems to be key for those, otherwise the leaves and stems
collapse with no return.  In the garden they will stand occasional nights in
the teens (F) without harm, but not periods of prolonged freezing
temperatures.  As with many early plants a critical factor seems to be the
length of time experienced below a certain critical temperature.  I find
with the early epimediums that the extending flower spikes will withstand a
short dip into the low 20sF much better than a longer period in the mid-high

Over the past couple of years I’ve been mass planting (sacrificing?) as many
Cyclamen species in the open garden as possible, in a variety of different
microhabitats.  Their response to the cold and snow has been interesting.
C. pseudibericum, intaminatum, cilicium, alpinum (trochopteranthum),
hederifolium and coum ssp. kusnetzowii (‘Kusnetzowii’) and most purpurascens
have remained completely and utterly unfazed and unmarked.  C. alpinum
disappeared beneath snow in extended bud and over the past couple of days
has just carried on where it left off.  C. coum ssp. coum f. albissimum
‘Golan Heights’ have surprisingly stayed in pretty good condition and has
resumed flowering, the leaves of the ‘regular’ (origin unknown) coum are
pretty messed up, as usual, but the flowers seem to be OK.  A few years ago
I put a couple of C. elegans (coum ssp. elegans) and hederifolium ssp.
confusum outside but brought them back into pots the following spring after
the leaves were trashed.  The additional C. elegans additions to the garden
have completely defoliated again and most of the h. ssp. confusum are also
in a sorry state, although some are OK.  The provenance of the hederifolium
ssp. confusum may be important but I didn’t track that for the plants I put
outside.  C. cyprium have also lost all leaves.  Rather surprisingly, a
number of mature (flowered) C. colchicum have pretty much defoliated also.
I wasn’t expecting that.  In all of the above cases the tubers are firm and
I expect them to be OK.  They are all at or just below the soil surface,
covered with a layer of grit.  Of course those that have defoliated will
lose maybe 50% of the potential growing season, so that may have an effect
down the road.  However, crocus like C. goulimyi and other Greek or lowland
Turkish species burn back maybe 50-75% by the end of the winter and they
build up very nicely outside.  The onco irises all put out new foliage in
the fall and this is trashed in the winter but they don’t mind at all and
continue to go from strength to strength, ditto for the larger Ipheions.
Interestingly there is a lot of variation in the ‘hardiness’ of Sternbergia
leaves and this seems to vary considerably within species.  Some forms of S.
sicula are completely undamaged, others burn back a bit and a few accessions
burnt off completely.  Of course the difference may be artificial if we’ve
got our names mixed up – and the bigger sternbergias are definitely
taxonomically confused!    I let my small greenhouse get down to the middle
20s F and the Cyclamen persicum in there don’t object at all.  As several
folks have reported, they are significantly hardier than generally supposed.

We are forecast for more cold and snow in 10 days so we’ll see what happens
then – I’m sure much of what I’ve reported is very dependent upon the growth
stage of the plant when the weather hits.



John T Lonsdale PhD
407 Edgewood Drive,
Exton, Pennsylvania 19341, USA

Home: 610 594 9232
Cell: 484 678 9856
Fax: 801 327 1266

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USDA Zone 6b

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