Autumn flowering bulbs are always a talking point amongst gardeners. Two of the most commonly planted are the confusingly named “Autumn crocus” (not a true crocus, botanically a colchicum) and the true (September-October) Autumn flowering crocuses.
Both perform a similar role in autumn gardens and signal that summer has drawn to a close.
Colchicums come in shades of pink and mauve, purple and white and in many flower forms.
The pale mauve flowered Colchicum autumnale, the “meadow saffron” or ”Autumn crocus”, is native to the British Isles, where it grows in damp meadows.
This is a clue as to how they are best grown in gardens.
They need a well-drained, but humus-rich soil retentive of summer moisture, so damp, but not waterlogged.
Poorer, lighter soils are best enriched with garden compost. Ideal position is in full sun or very light, dappled shade.
Colchicum autumnale ‘Album’ produces many small, white flowers, ‘Alboplenum’ has larger double blooms, ‘Pleniflorum’ has beautiful rose-mauve flowers.
The most spectacular are the fuller flowered varieties such as ‘Waterlily’. It is aptly named, as it looks just like a miniature mauve flowered water lily flower.
Corms can be planted in July or August, by which time their foliage will have mostly died down, about 7.5cm/3ins deep and 15cm/6ins apart.
Established clumps are also best divided at this time, about every three or four years and re-planted straight away. This will keep them flowering freely.
Colchicums look wonderful when leaf-less and in flower. They make an effective understorey to complement Autumn flowering or fruiting shrubs and perennials such as Japanese anemones, asters, hardy fuchsias and silver leaved artemisia or stachys.
However, the leaves, produced in spring, can be large, about 23cm/9ins tall and10cm/4ins wide, and can look untidy, as they tend to flop over if unsupported. This needs to be taken into account when devising planting schemes with them.
The leaves are best partly masked by spring flowering bulbs, such as dwarf narcissi, or supported by the developing shoots of perennials.
There are several species of the true autumn flowering crocus.
Crocus speciosus is the earliest to flower, in September; its blue or violet blooms have delicately veined petals.
Forms include ‘Albus’, which has white flowers with pointed petals and a yellow centre, ‘Conqueror’, which is a bright violet-blue with orange-red stigmata and the large, lavender-violet flowered ‘Aitchisonii’.
The saffron crocus, Crocus sativus, has mauve petals and long, orange-red pistils. This is a native of the eastern Mediterranean and needs a really sunny spot and a summer baking to flower freely.
Autumn crocus do best in a well-drained soil in a sunny position. Shelter from wind is also beneficial, as the stems tend to be taller than spring flowering crocus and are more prone to wind damage. When suited, they will naturalise, increasing by both off sets (young corms) and seed.
As with the colchicums, corms are best planted in July, about 7.5cm/3ins deep and 10cm/4ins apart.