Crocosmia - or Montbretia as once were - are probably not as popular as they should be, because of the huge clumps of untidy foliage that is often to be seen in gardens old and new. If grown properly, and cared for, then the Crocosmia are a welcome display of colour in the herbaceous or other borders, from late summer through till the last days of autumn.
Crocosmia grow from corms - though often referred to a Crocosmia bulbs - and have the classical corm habit of producing a new corm - for the next year on top of the current corm which dies off.
The flower colour of Crocosmia bulbs ranges from light yellow - cream almost - through to the deepest red. Foliage is in varying shades of green, with bronze foliage on a few varieties.
The flowers are clustered on top of stems held above the lance-shaped grass-like foliage - sometimes mingling with that foliage. Flowers are normally horn or funnel shaped with a good succession of new flowers following the faded individual flowers. The stems of flowers make for good cut-flowers and are a good addition to the indoor cut-flower display. Gardeners, be aware that the flowers are sought after by flower arrangers!
Foliage dies off in the Autumn with straw colours and is not unattractive in the autumn/winter garden. The dense foliage clumps of the crocosmia bulbs - corms- makes for good ground cover, with little else being allowed to grow under it.
Crocosmia 'Severn Sunrise' - Crocosmia 'Solfaterre'.
Crocosmia are relatively easy to grow from corms or bought as small plants from the nursery or garden centre. They can be bought as dormant corms throughout the autumn and winter and planted right away. Plant the corms around three inches deep. Crocosmia bulbs can also be bought as pot grown plants - often just a few blades of foliage, but also as good established flowering plants - and can be planted in their permanent positions as soon as bought.
They are happy in full sun or at the edge of a shrub or herbaceous border under light shade. Soil type is almost no problem, though well drained soils seem to suit Crocosmia better. Will normally survive and even thrive in drought conditions. Montbretia bulbs are ideal for dry gardens or on the edge of woodlands.
Heights of Crocosmia according to variety, but rarely more than 3feet - 90cms. Mostly 2feet or 60cms. They will soon start spreading after the first year of planting so for the best display, allow for room to spread. Once established, the clumps of corms should be lifted in spring and divided. this will ensure good healthy growth with a good ratio of flowers to foliage. Older, undivided clumps seem to lose their ability to flower after several years.
Because of their tolerance to drought, Crocosmias are admirable subject to plant as the base of a wall or dry banks.
Foliage is best left on the plant after dying down, for some Crocosmias are prone to hard frost damage. Special plants and collections should be given some form of protection for the winter months - a mulch normally suffices. Staking of the clumps is not normally required, and the flower stems will normally arch over - sometimes hiding the attractive markings within the individual flowers.
There are few problems to worry about with Crocosmias, though red spider mite can be troublesome - especially in dry areas and hot dry summers. Red Spider Mite on Crocosmia will manifest itself with a severe yellowing of the foliage.
Crocosmia can be grown from seed - a rather lengthy process to get flowering plants, can be up to four years.
Division of the clumps in spring is by far the best way, with small montbretia bulbs divisions soon developing into worthwhile clumps after the first year. When lifting in spring, there is no need to take off the old last years corms. leave them to provide organic matter in the soil.
Because of the increasing interest in this group of plants, plant breeders are bringing new varieties forward to sell each year. The following are some of the well tried and trusted varieties known to the writer to give plenty of flower and relatively trouble free years of pleasure.