TOW Crocus species--Fall Bloomers

Mary Sue Ittner
Tue, 04 Feb 2003 17:23:39 PST
Dear All,

We haven't heard from Jane McGary so she must be away or busy as she grows 
quite a few Crocus species. I ordered a few from her surplus list last fall 
and really enjoyed them. I have had no luck at all with the fall blooming 
ones staying on in my climate. They bloom the first year and maybe the 
second and then I never see them again. At least that has been my 
experience growing them in the ground. I have tried ones that were 
supposedly Mediterranean in nature, but I've wondered if they just need 
more early water then they get for me or maybe I don't have enough sun. I'm 
thinking maybe I'll keep the ones from Jane in containers and start 
watering them in August and see if that does the trick although I'd rather 
have them in the ground.

When we have discussed this in the past on the old IBS Forum people thought 
the autumn ones would work better for California. Since Jane isn't 
responding I am going to repost the topic of the week introduction she made 
for me when I was doing the old IBS Topic of the Week since it is a very 
interesting one.

Mary Sue

Mary Sue asked me to prepare a TOTW introduction on the genus Crocus, but
since it's so large, I will just address those of interest at this time of
year, the fall-flowering species. Some forum members have mentioned that
they don't grow crocuses because they live in very warm areas where the
common kinds (derived from C. vernus, C. chrysanthus, and C. biflorus)
don't flower well. If you have that problem, you will find fall species
that are much better suited to your climate, since many of them come from
warm Mediterranean regions and are not very winter-hardy. The remarks about
hardiness below reflect my experience growing them where average winter
lows are about 12-15 F (around -12 C), with colder spells about every
fourth year. I grow all of those mentioned in the open as well as in bulb
frames, except for Cc. goulimyi, boryi, laevigatus, longiflorus,
nudiflorus, and tournefortii, which do well in unheated bulb frames. The
soil in my garden is mostly very well drained, and it gets quite dry in
summer except where artificially watered.

One problem with obtaining these plants is the fact that they must be
shipped earlier than the usual fall-planted bulbs in order to survive well.
Therefore, they are expensive and sometimes arrive in bad shape from being
stored too long. It is best to order from a firm that will make an early
shipment in late summer.

All the fall crocuses are lavender-blue or white (except C. scharojanii, a
snow-melt species which is very difficult to grow). Most of the blue ones
have white forms in cultivation.

C. banaticus is the most unusual-looking of all crocuses and has sometimes
been placed in its own genus. Its two sets of tepals are very unequal in
length, so it looks like a little iris. It comes from Romania and is hardy
to about 0 F, and it enjoys deciduous shade. The white form is extremely

C. boryi from the Peloponnese has large, substantial white flowers. It is
probably hardy outdoors to about 25 F and increases very slowly for me.

C. cancellatus has bright violet flowers with striking dark purple
"feather" markings on the exterior. It is a rapid increaser, hardy to
perhaps 10 F, and wants a very gritty, scree-type soil, with a dry summer.

C. cartwrightianus is believed to be the ancestor of C. sativus (see
below). It has smaller flowers, and the scarlet stigma is almost as large
as in the Saffron Crocus. The white form is probably more common in
cultivation than the type, which is lilac-blue. A warm summer and soil of
moderate fertility suit them; they are hardy to at least 10 F.

C. goulimyi has a distinctive flower form, more bowl-shaped than
goblet-shaped. It is another one from the Peloponnese, and it is not very
winter-hardy (despite the claim in catalogs that it is hardy to Z4!). It
should be perfect in California. The typical form is soft lavender; there
is a beautiful (and expensive) white form. These both increase fairly well.
A friend here bought corms under this name from a US distributor which
turned out to be C. kotschyanus, a hardier species.

C. hadriaticus has several botanical forms and cultivars. Also from the
Peloponnese, they are remarkably winter-hardy (to at least 10 F) and
extremely floriferous. Most forms are white, but f. lilacinus is flushed
lavender. This species self-sows readily and is very easy to raise from seed.

C. kotschyanus is present in many gardens, but the form commonly
distributed is notoriously shy-flowering; it seems to put all its energy
into offsets. There is a white form, also shy-flowering. Two clones,
'Reliant' and one distributed under the collectors' initials JRJK, flower
much better, and they also increase reasonably fast. The corms are
unmistakable in their very flattened, asymmetrical form. This species is
pretty cold-hardy but needs a dry spot, both summer and winter. It has
grown here for many years under the south overhang of a deck.

C. laevigatus is a true midwinter bloomer from the Greek islands. The one
usually grown is the clone 'Fontenayi'. It has bright blue-lavender flowers
with darker veins and flowers from about Dec. 1 to Jan. 15. It is a bit
hardier than one would expect, but should be grown in pots in most areas,
if only to enjoy the flowers indoors at Christmas. I think it would survive
outdoors to at least 15 F. for short periods.

C. longiflorus has large, very fragrant lavender flowers. It does not
offset much and therefore is hard to obtain.

C. medius is widely available. It comes from mid elevations in the Italian
mountains and is hardy to at least 10 F. The flowers are rich red-violet
and very shiny, borne in profusion. 'Millesimo' is purported to be more
vigorous than other clones, but seems about the same to me.

C. niveus has pure white flowers that are remarkably large. It is
moderately hardy (perhaps 10 F) and increases very slowly but usually sets
seed. It seems to enjoy a very dry summer dormancy.

C. nudiflorus is also large-flowered, and is bright violet. The leaves do
not emerge until spring (hence the name), so this is a good choice for
colder areas. It is native to alpine meadows and should not dry out too
much in summer, but must have excellent drainage. It is another slow

C. ochroleucus from southern Turkey and Lebanon is quite a surprise, having
survived -6 F (about -22 C) here. I think it did because it grows very deep
in the soil, even though both corms and flowers are small. The flowers
appear in late November and persist through all weathers, but only open on
sunny days; they are white with a prominent gold base. It increases fast
and once established, will probably always be in its site.

C. pulchellus is a medium-sized species that is quite easy to grow in
temperate gardens. Several clones have been selected, notably 'Zephyr' and
'Michael Hoog'. It increases fast and produces a lot of flowers. It also
sets a lot of seed.

C. sativus is the Saffron Crocus, grown for the culinary flavoring and
dyestuff for millennia. It is a sterile triploid, though several clones
undoubtedly exist by now. It has dark-veined purple flowers and the
well-known long scarlet style that is the useful bit. It needs a warm
summer to flower well and appreciates freshly prepared, rich and gritty
soil. It should be planted fairly deeply and divided every third year.

C. scharojanii is the only yellow-flowered species. It comes from alpine
meadows in the Caucasus and is only rarely seen in cultivation. Mine, grown
from wild-collected seed, have not yet flowered, but I do not despair of
seeing it someday. It hates disturbance and apparently never becomes fully

C. serotinus has several subspecies; one, subsp. clusii, is sometimes grown
as C. clusii. It comes from Spain and Portugal and is moderately
winter-hardy (perhaps 10 F), but the leaves are susceptible to frost
damage. The flowers are various shades of violet or lavender, with orange
stigmas. The corms increase rapidly.

C. speciosus is the hardiest fall-flowering species and can be grown in the
US Northeast. It is also one of the showiest, with large flowers borne as
high as 8 inches from ground level on long tubes, so it can be planted
among groundcovers. The first ones are just coming into flower here now,
but it mostly blooms from mid-October on. All the named varieties I've
tried are vigorous and persistent, including the very striking 'Albus'. It
does well in half shade or sun and seems to enjoy a cool soil and water in
summer. This is one everybody should try.

C. tournefortii, from Mediterranean islands, is unique in that its flowers
do not close at night or in dull weather. It is one of the "bluer" fall
species, a low-growing plant that increases moderately in a pot in an
unheated bulb frame here. The flowers are sweetly fragrant of honey.

C. vallicola is distinguished by its white tepals with long threadlike
appendages on the tips. It is a Turkish alpine plant and has done well here
outdoors on a raised bed in part shade. It increases slowly. Though
expensive, it is worth obtaining for its hardiness and tolerance of summer

Jane McGary
Estacada, OR (SE of Portland)
Mary Sue Ittner <>
California's North Coast
Wet mild winters with occasional frost
Dry mild summers

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