TOW Crocus Species in the Garden

anthony goode
Sun, 02 Feb 2003 04:52:58 PST
When Mary Sue approached me about moderating this subject I expressed
some doubts.  My experiences are based on gardening in the UK, many
thousands of miles from where most of you garden.  Crocus species are
often quite particular about their requirements and even within the
boundaries of the UK growers have very different experiences according
to local climatic and soil conditions.  Having recently become a
father for the second time my time for this potentially huge subject
may be limited.  However I prepared a piece on this very subject for
the Alpine Garden Society Bulletin a few months ago and I am
reproducing this below.  It is rather long for a discussion group.
Reading the first and last paragraphs will give you a good summary,
the bulk of the text deals with ten individual species in detail.

Knowledge of the prevailing conditions in a plants native habitat is
often useful when attempting to grow unusual plants.  Finding this
information and comparing it to your conditions may be the key to
deciding whether a particular Crocus species will grow in your garden.

Crocus Pages web site has images of most taxa and some basic
information about all.

I have also posted some images of garden worthy crocus at a page on
the PBS wiki  which Mary Sue kindly prepared for me.  I will add to
these according to the plants covered in the discussion.…


Asked to write a piece on ten top crocus species for the garden I was
initially enthusiastic.  As a holder of one of the NCCPG National
Collections, I grow a wide range of Crocus species.  However, asking
an enthusiast to choose just ten from so many (there are 127 species
and subspecies currently recognised in the genus Crocus,) is perhaps
unfair!  Furthermore, the stipulation that the chosen ten should be
good garden plants is a complication.  Where is the garden?  What is
the soil type, aspect, local climate?  I live in Norfolk UK with
relatively dry summers and I garden on a light, sandy soil, as you
read these notes you should give consideration to your local
conditions.  No crocus species are truly native in the British Isles
although Crocus vernus and Crocus nudiflorus have been naturalised in
a few locations for centuries.  The genus Crocus has a distribution
centred on Turkey and the Balkans but including Morocco, Iran, Western
China and Poland at its edges.  So in British gardens at least we may
struggle to find them an ideal home.  However the two species
mentioned above provide an ideal starting point for this short
article.  Both are clearly well able to adapt to life in a maritime
climate having survived for so long here.  They also point the way to
the division of the chosen ten into two groups, spring flowering and
autumn flowering.

Crocus nudiflorus is native to Southern France and Northern Spain
being especially common in the Pyrenees, its native habitat being
moist meadows, and the local climate involving significant summer
rain.  It is easily cultivated in undisturbed borders in the garden,
while it can also be naturalised in grass as in the alpine meadow at
the RHS Gardens at Wisley.  Increasing by stolons, which spread out
from the parent corm, it can also be raised from seed, flowering in
three or four years from sowing.  The plant is leafless at flowering
time, the purple flowers being carried aloft on a strong tube which
stands up to the early autumn weather much better than the more widely
and cheaply available Crocus speciosus.  In my experience, in dry East
Anglia, it increases only slowly in the garden but will survive even
in relatively overgrown situations.  I am gradually establishing more
Crocus nudiflorus in the garden by planting out the flowering size
corms at each repotting.  I grow on the smaller corms and stolons in
pots, where they make flowering size in two or three seasons and do so
more reliably than in the open garden.

Crocus speciosus is certainly the most easily obtained autumn
flowering crocus species, available from most garden centres where you
can get ten corms for the price of one of the 'rarer' species.  Native
to Turkey and the Caucasus where it grows in alpine turf, pasture and
light woodland, in the garden it can be grown in a variety of
positions in most soil types provided that it gets a dryish summer
rest period.  Although it can also do well in grass, given the
vagaries of the British summer, it may be best to plant Crocus
speciosus in free draining soil in raised beds.  I find that the
flowers are very prone to flop; growing it through low growing plants
can help provide support.  It is also cheap enough to be planted in
quantity in patio pots interplanted with winter pansies for some
autumn colour by the back door.  The named clones offered in commerce
are forms selected for flower size, good colour and markings.  Some of
the nicest have very strongly veined inner petals, a feature quite
common in wild forms.  Plants raised from seed of 'unselected' Crocus
speciosus are usually smaller flowered than the horticultural clones,
very attractive but offering no advantage to the gardener over the
trade forms.

Crocus pulchellus, closely related to Crocus speciosus, is also
offered by some garden centres but the message here is 'buyer beware'
as some Dutch stocks are mixed hybrids with Crocus speciosus.  These
two species combine to produce a range of intermediate forms, some of
which are very attractive, however few have the delicate charm of true
Crocus pulchellus.  In the wild the two species have adjacent but
distinct distributions, Crocus pulchellus, the more western, being
common through NW Turkey and the Balkans.  Its native habitat is in
moist grassland and thin woodland and it experiences some summer rain.
The yellow-throated flowers with white anthers (the two obvious
differences with Crocus speciosus,) are usually lilac.  They have a
distinctive goblet shape and are carried on stronger tubes than Crocus
speciosus, which makes it less prone to flop over than its close
relative.  Like Crocus speciosus it can be grown in a variety of
situations in the garden, but is especially suited to raised beds and
the rock garden where the beautiful flowers can be closely observed.
It increases by producing small cormlets around the parent corm, grown
in pots under glass the rate of increase can be rapid.

Crocus niveus is less widely grown than the aforementioned species but
can be an equally good garden plant.  This species has some of the
largest flowers in the genus, flowers which are produced with the
leaves (the previous three species flower before the leaves appear),
and borne on strong tubes.  The flowers may be white or lilac, in the
latter case they are usually strikingly bicoloured.  Surprisingly it
failed to impress in RHS trials a decade ago but in my experience this
species stands up to bad weather better than most autumn crocus.
Native to Southern Greece it grows in olive groves and dry scrub at
relatively low altitudes.  In the garden it prefers a sunny well
drained position and when suited it will increase by corm division and
produce seeds.   Seed is usually available in the AGS seed exchange
and represents the cheapest way to acquire this (and other) species.
However, this plant is available from specialist bulb suppliers and
its ready increase and showy flowers make it worth some expense.

Crocus banaticus is unique in the genus having three outer petals much
larger than the inner ones.  The flowers are usually lilac or purple
with a froth of concolorous style branches at the centre. There are
several white forms in cultivation; a particularly large flowered one
has recently won awards at AGS shows.  Found in the wild almost
exclusively in Romania, this is a plant of meadows and deciduous
woodland, which enjoys continuous moisture through the year.  This
makes it the best autumn flowering species to choose if you cannot
provide the well-drained site that most of the others need to thrive.
Equally if your garden experiences long periods of drought, this is a
plant to site with care, as it prefers to be kept moist (though not
waterlogged) in summer.  It can be associated successfully with dwarf
ericaceous shrubs and will also grow happily in grass.  Seed may offer
the best method of increase, as corms do not usually increase very
quickly in the open garden.

All the species discussed so far will flower between September and
November in the garden depending on the season.  There are many others
that will do well in the garden given suitable conditions; CC.
goulimyi, kotschyanus, longiflorus, laevigatus and tournefortii could
be used to make up the chosen ten.  The brief here, however is to
detail five for autumn and five for spring, which brings me to Crocus
vernus the other naturalised alien mentioned earlier.  Crocus vernus
has a very wide distribution, stretching from the Spanish Pyrenees,
through the Alps into the Balkans and north to Poland and Western
Ukraine.  Typically a mountain plant, it can be seen carpeting alpine
and subalpine meadows and woodland soon after the snow melts.  Two
subspecies are recognised.  Subspecies albiflorus is generally
associated with the higher parts of the Alps and Pyrenees where the
small, generally white flowers may be seen as late as early July in
the highest places. (See the images on wiki.)  From a gardeners point
of view however it is subspecies vernus that is the garden crocus par
excellence.  This is the plant from which the popular Dutch crocus
have been selected.  The clones in commerce are generally larger
flowered than 'typical' Crocus vernus, but even in unselected forms
the flowers are of good size and robust constitution.  This is indeed
'everyman's crocus', thriving in all except the hottest and driest
places and indifferent to soil type.  It is perhaps at its best when
grown in grass and is memorably used in many parks and gardens
throughout the UK.  There are a number of very attractive forms
available from specialist nurseries and through the seed distribution.
Some of these have in the past been recognised as distinct species.
Names such as Crocus scepusiensis and Crocus heuffelianus refer to
plants from the east of the natural distribution with flowers having a
darker tip to the petals.  An Italian plant with purple almost waxy
petals has been known by the name Crocus napolitanus.  All of these
plants are good doers in the garden, very suited to the rock garden
where the Dutch crocus can look rather blousy.  All forms are easily
raised from seed and will increase by corm multiplication over the

Spring-like weather in the UK can occur in almost any of the winter
months and Crocus imperati, which is officially a spring flowering
species can flower as early as December.  Native to Western Italy it
flowers in the wild from January to March, buff coloured buds marked
with purple stripes opening to reveal bright lilac purple inside the
flower.  There are two subspecies separated by small botanical
differences.  Despite the often inclement winter weather this species
makes a good garden plant in well drained soils in a sunny spot.  I
have seen buds encased in ice after a January snowfall open in perfect
shape a week later.  In a cool settled spell the plant can be in
flower for four or five weeks at a time of year when there is little
colour in the garden.  Some specialist bulb suppliers offer a form
named 'De Jager' which is probably a form of subspecies suaveolens.
Subspecies imperati, which may have larger more extravagantly marked
flowers, is occasionally offered by the seed distributions.

Flowering later in spring and an equally good garden plant, Crocus
corsicus is another species offering a dramatic colour change.  As it'
s name suggests it is native to Corsica, growing in scrub and on rocky
hillsides.  (See The Alpine Gardener Vol 70, p 130 for a photograph of
this species in the wild.)  Not usually flowering in the garden until
late February or early March, the yellowish outer petals are usually
strongly feathered purple but open to reveal vibrant lilac inner
surfaces.  Once again this is a plant that needs a well-drained soil
and a sunny spot to thrive in the garden.  I occasionally give
lectures to gardening clubs about Crocuses and feedback from gardeners
in the cooler, wetter North West of England suggests that this species
is less reliable outdoors but remains an excellent subject for winter
colour in pots under cold glass.  Some specialists still supply Crocus
corsicus reasonably cheaply and this clone can increase quite freely
given optimum conditions.  Seed is occasionally available.

I hesitate to mention Crocus tommasinianus for to some enthusiasts it
is a roguish weed but for the purposes of this article its merits
(just) outweigh its misbehaviours!  Here is a species that when suited
can colonise large areas quite quickly.  Increasing by seed and the
production of many small cormlets it has some of the vices of the
much-maligned Grape Hyacinth, Muscari armenaicum.  However, it redeems
itself by brightening the late winter days with commonly lilac flowers
sometimes with a buff or silvery reverse to the petals.    Found in
the wild growing in deciduous woods in S. Yugoslavia, SW. Bulgaria and
NW. Hungary, it is fairly uniform but can be abundant when found.
There are a number of named forms available in commerce and from
specialist bulb suppliers.  'Roseus' has pinkish lilac flowers, the
closest thing you will find to a pink crocus.  'Pictus' has darker
purple flowers with silvery tips to the petals.  'Bobbo' is lilac with
cream coloured outer petals and all the petals have white tips, a
striking combination especially when the flowers are half open.  There
is also a claret coloured form that is more difficult to find but
equally garden worthy.  All of these unusual forms will set seed but
their progeny tend to be a mongrel bunch, rarely matching the parents
exactly.  Crocus tommasinianus will tolerate more shade than most
crocuses, (they are generally a family of sun lovers,) and can
associate well with snowdrops in both formal and natural plantings.
It also does well in grass.  It is probably not a wise choice for the
rock garden owing to its' all conquering capacity although I have
heard of people who cannot establish it in their gardens owing to its
palatability to rodents.  Unfortunately all crocuses are potential
rodent food, their corms being a neat parcel of starch!

Crocus biflorus is a complex of many subspecies mostly found in
Turkey, which despite extensive study and research in garden,
laboratory and in the wild continues to defy the efforts of man to fit
it into a neat classification.  It does however offer the gardener
many attractive garden plants.  In commerce the so-called 'Species
Crocus' are often either forms or hybrids of Crocus biflorus.  These
are usually excellent garden plants given a sunny position although
they are not as robust as the large Dutch crocus derived from Crocus
vernus, being less tolerant of summer moisture.  Apart from those
commonly available there are several forms of Crocus biflorus offered
by specialists.  Crocus biflorus weldenii 'Fairy' has pure white
petals, the outer three intensely stippled with lilac flecks.  Crocus
biflorus alexandrii is also pure white, this time with dark purple
outer petals, a very striking combination as the flowers open.  The
so-called 'Scotch Crocus' is a sterile form of Crocus biflorus
subspecies biflorus, which is white with a yellow throat and prominent
purple veins on the outer petals.  All of these will thrive in a
well-drained soil in sun.

As with the autumn selection there are species that have been omitted
from this chosen ten which will succeed in many gardens, notably CC.
sieberi, etruscus, minimus, pestalozzae, malyi and fleischeri, plenty
of material for the 'second eleven' article.  We are fortunate that so
many Crocus species are in cultivation, available from specialist
suppliers or as seed from various exchanges.  This very availability
indicates that these species are not difficult to cultivate given a
little extra care.  The cultivation of crocuses in the open garden
does have a number of drawbacks.  The corms are palatable to mice,
rats, voles and squirrels in the UK (and a whole range of similar
rodents in the USA).  Various precautions are possible if you
experience these problems but the battle is never likely to be
entirely won.  Like many growers I often resort to pot cultivation, if
only to keep a back-up stock to replace any losses of the less common
species.  Also the delicacy of the flowers, which makes them so
attractive, makes them vulnerable to inclement weather.  Autumn
flowering species of Mediterranean origin adapt well to areas that
have a climate with Mediterranean influences.  I find that the autumn
flowering species can look bedraggled during a prolonged rainy spell,
although this damage to the flowers is only superficial and the plants
still grow strongly.  Species from high mountains, especially those
which flower close to melting snow, are often more challenging in
lowland gardens where winter temperature fluctuations induce growth at
times when light levels are low, subjecting plants to many unfamiliar
stresses.  The cultivation of all of these plants in the garden
(except perhaps Crocus vernus and Crocus tommasinianus) relies on the
choice of a suitable position.  As gardeners we often need to give
attention to plants' individual requirements to get the best out of
our 'investment'.  Given this attention to detail it is possible to
enjoy a variety of Crocus species flowering in the garden from
September until March.

Further Reading.

Bulbs.  Roger Phillips and Martyn Rix. Pan. ISBN 0-330-30253-1

The Smaller Bulbs.  Brian Mathew.  Batsford.  ISBN 0-7134-4922-5

Growing Bulbs.  Brian Mathew.  Batsford.  ISBN 0 7134 4920 9

Bulbs for the Rock Garden.  Jack Elliott.  ISBN 0 7134 7424 6

Growing Bulbs.  Martyn Rix.  Timber Press.  ISBN 0 7099 2248 5

The Crocus.  Brian Mathew.  Batsford 1982 ISBN 0 7134 3390 6  (now out
of print but obtainable through specialist second hand book dealers.)

Journal of the RHS, 'The Garden' Vol 21, Pt 7, pp402-405.  Report on
the trials of Autumn crocus at Wisley by Brian Mathew and Alan

The Crocus Pages web site has
information and images of all the plants mentioned.

Tony Goode.  Norwich UK.  Mintemp -8C  (Zone8?)

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