Yes, a Friday geeky plant post. On schedule 🙂
Corydalis has hundreds of species spread across the temperate Northern hemisphere, from forests to the high screes of the Himalaya. They are in the same family as poppies.
The high alpine species are a real challenge for the low-altitude gardener, and the semi-desert species from Central Asia are really growable only with some protection from the wet, or they rot.
Some of the annual species are common weeds (fumatories).
This still leaves many that are perfectly growable in the open garden. Some such as C.bracteata, C. turtschaninovii and this beautiful pale blue C. ornata are accustomed to the severe cold winters of Siberia and are really better suited to continental climates with colder winters than mine.
The easiest Corydalis in my garden are the various cultivars of Corydalis solida and its relatives.
The wild type C.solida can be a feeble squinny flowered thing but many beautiful cultivars have been selected, usually in shades of red and pink or purple. They grow from little tubers the size of hazelnuts and reliable double each year. They are lovely in flower and then quickly die back below ground in late spring, until next year. This is the pure white ‘White Knight’:
This next one is the lovely ‘Craigton Red’, bred by friends of ours in Aberdeeen:
The tiny cream-flowered Corydalis malkensis seeds itself around in the garden but never becomes a pest. Just in front of it you can see a rather poor purple wild form of C. solida:
This group grow happily together in the shade of deciduous shrubs and trees. Here you can see Craigton Red, malkensis, wild type solida and at top left you can see the emerging leaves of one of the lovely blue flowered species which I will cover below.
Some more specialised species which would be happier perhaps in drier gardens are Corydalis integra and the dainty Corydalis henrikii:
This is Corydalis lutea. This grows in walls in limestone districts like mine and is widely naturalised. I love it but find it difficult to establish anywhere except in a wall.
The lovely leaves of this next, Corydalis cheilanthifolia, are it best feature. It makes a nice plant in a rock garden crevice but is not very hardy or long lived. It seeds itself around so I never lose it completely.
I finish with these lovely blue flowered species. They flower in late spring. They differ from the solida group in that they are herbaceous perennials without tubers. They benefit hugely from frequent division and replanting. The true Corydalis flexuosa was the most popular one, with numerous named forms. If it had a fault it was that it would die back in the heat of summer. Its hybrids with C. elata and similar species are very vigorous and much less prone to dying back in hot weather. If I had to recommend just one then it would be the superb ‘Craigton Blue’ (again selected by my friends Ian and Maggi Young in Aberdeen.