This is a most valuable race of bulbous plants in that they are particularly suited to cool, shady positions, where they will grow to perfection. And any plant that will do this is most useful for there are many such places in all gardens and very few plants with which to fill them. They will also produce a prolific amount of bloom when growing in soils of quite a poor nature, another factor in their favour.
In addition they produce both an enchanting bloom and delightful fern-like foliage, blue-grey in colour, resembling the popular maidenhair fern. By a selection of varieties, the flowering season can be extended from mid-March to the end of June, during which time there should be at least some colours in the shady border or shrubbery. This is an excellent plant for a town garden, where hedges, trees and shrubs will generally be found to supply the necessary shade.
There are Corydalis which grow to a height of little more than 4 in. which are ideal for a shaded rockery – the species C. cava bears its bloom on 9-in,and C. nobilis produces its blooms on almost 18 in. in length.
The Corydalis enjoys a soil containing some peat ormould though it will flourish in one that contains little humus provided it is moist and cool. The bulbs should be planted during late autumn – October is a suitable time and they should be planted 3 in. deep. Reserve a in the sun for the two Chinese species, Cheilanthifolia and Wilsonii, for they seem to like at least their share of late spring sunshine. The plants will increase naturally from self-sown or they may be lifted and divided like snowdrops when flowering has finished, but before the foliage tends to die away, which it will not do until early autumn.
Corydalis angustifolia. From the Caucasus and must have a shady place and a light soil to produce its pale lavender sprays to advantage. Flowering to a height of about 8 in., it blooms from mid-March until May.
C. cava. Named because of its curious hollow bulb. A lovely variety for the shaded rockery, producing its dainty sprays ofor white above its rich grey foliage.
C. densiflora. From Greece and of dwarf habit coveting itself with a mass of rosy pink flowers in early spring.
C. solida. Similar to angustifolia and though producing not quite so striking a bloom, it is of more compact habit.
C. Wilsonii. Requiring more sunshine than the others, this is the most outstanding species of them all. The bright yellow flowers delicately marked with green are of more prostrate form. The foliage is of darkest green which accentuates the yellow bloom which is at its best during April and May.