The spring blooming corydalis kick off the garden year. As soon as the bulbous plants have withdrawn, the herbaceous perennial species show off. Among them there are real longtime bloomers and color wonders.
Profile of corydalis:
Scientific name: Corydalis
Plant family: fumewort family (Fumariaceae)
Other names: –
Sowing time: from February inddor
Planting time: mid-September to October.
Flowering period: March and July
Location: sunny to shady, depending on the variety
Soil quality: depending on the variety
These information are for temperate climate!
Use in: natural garden, forest garden
Winter hardiness: hardy, USDA Plant Hardiness Zones: 6 (-23 °C / -5 °F)
Bee and insect friendly: Yes
Plant characteristics and classification of corydalis
Plant order, origin and occurrence of corydalis
Corydalis can be divided into two groups: the bulbous species appear in early spring after snowdrops and spring snowflake and, after flowering, are even faster than most bulb flowers. The herbaceous perennial species, on the other hand, usually form bushy clumps and keep their decorative foliage throughout the season. It is important to know which group the corydalis belongs to if you want to use the plants in the garden.
The plant genus Corydalis belongs to the family of the fumewort family (Fumariaceae). About 300 to 400 species and subspecies are known to occur in the temperate zones of the Northern Hemisphere and in South Africa. The tuber-forming species make up around a quarter of all corydalis. The genus includes annual and perennial, but always herbaceous species that are sometimes summer and sometimes evergreen.
The intermediate corydalis (Corydalis media) is common in Central Europe. Its natural habitat is primarily herbaceous deciduous forests. Around five species and hybrids are cultivated in gardens. The best known of these are the hollowroot-birthwort (Corydalis cava) native to Germany and the spring fumewort (Corydalis solida). The yellow corydalis, which is also often planted, is no longer assigned to the genus Corydalis, but to the genus Pseudofumaria. Its former botanical species name Corydalis lutea was therefore changed to Pseudofumaria lutea. Accordingly, the plant is also called yellow fumewort.
Characteristics of corydalis
The species of corydalis scores with a wide variety of growth forms: from alpine dwarfs to polster-forming joint plants and climbing species to specimens up to one meter (40 in) high, everything is covered here. The species cultivated in the garden usually reach heights of between 10 and 40 centimeters (4 and 16 in).
The leaves of the corydalis are mostly pinnate or lobed several times.
Depending on the species, corydalis bloom in violet, pink, red, white, yellow and blue between March and July. The bisexual flowers grow in panicles or racemose inflorescences. The upper petal of the flower forms a spur at its base. Since this bears a certain resemblance to the pointed bonnet of the crested lark, the plant was given the German name “Larkspur”.
After flowering, double-layered pods develop that contain numerous seeds.
Corydalis – cultivation and care
The demands on the location can vary from species to species. Some species prefer shady or semi-shady locations. Others, on the other hand, thrive better in sunny locations.
Most types and varieties of corydalis prefer a humus rich, well drained soil in partial shade. The blue corydalis (Corydalis elata) copes well in a shady spot. While the blue prefers fresh soil, white corydalis (Corydalis ochroleuca) also tolerate drought. As you can see, it is important to find out more about the requirements of each species before planting.
The best time to plant is from mid-September to October. The plants are often available pre-cultivated in pots. But the tubers are also available in stores. They are placed 5 centimeters (2 in) deep into the ground and about ten centimeters (4 in) from each other. Corydalis does not require any special care.
The water requirement depend on the respective location and the weather conditions. As a rule, however, watering should be carried out regularly, especially in summer. If the corydalis grows already on a rather damp floor, it is advisable to water at longer intervals, as too much moisture can lead to root rot.
If the soil contains sufficient humus, additional fertilization is usually no longer necessary. Otherwise, as soon as the flowers begin to wither, a fertilizer for tuber-flowers can be administered every 3-4 weeks.
If the plant spreads too much, the annoying specimens are removed. If you want to prevent the plants from spreading in the garden by self-sowing, you should remove the withering flowers before the seeds ripen.
If you want to sow the tuber plants in a targeted manner, you have to be quick to harvest seeds from your plants. If the seeds ripen immediately after flowering, they are carried away by ants. A clever spreading strategy, because the insects are after a nutritious appendage of the seed. The prey is sometimes lost during transport and then germinates in the most curious places.
If you want to sow corydalis in pots, you have to consider that it belongs to the cold germs. Accordingly, the seeds must be subjected to a cold treatment before sowing. To do this, they are placed in the refrigerator for about 10 days, for example, which removes the inhibition of germs and promotes germination. Then potting compost is mixed with about a third of coarse sand and placed in an appropriate planter. In addition to potting compost, coconut fiber is also very suitable because both substrates are permeable and low in nutrients.
The seeds usually have different sizes. The larger ones are covered with sand and the smaller ones are spread over the substrate and only slighlty pressed on. Now the whole thing is moistened and kept evenly moist until germination. Then cover the planter with a clear film or glass and put it in a cool place until the seeds germinate. It is advisable to briefly remove and air the film or the glass from time to time, this will prevent mold growth.
Direct sun should be avoided in the first six weeks after budding. The small seedlings can be isolated or pricked out about 5-8 weeks after they have emerged. When planting out, one should be very careful not to injure the young roots. It is best to plant them in smaller groups, so they usually develop more vigorously.
The tuber-forming species also spread over tubers, which is why large stocks quickly emerge. If you want to propagate them, dig out the tubers in late summer or early autumn and put them back into the soil at the desired location. Before that, let the cut surfaces dry a little. Rhizome-forming species such as the blue corydalis can be divided. This is best done directly after flowering. To do this, dig out the rhizome of the plant, carefully separate it into several sections and plant it again directly.
Diseases and pests
Corydalis can develop root rot, which is primarily a result of too much moisture. Snails, which can cause severe feeding damage, should be mentioned as possible pests.
After flowering, this plants overwinter. Most corydaliss are usually hardy plants. Despite everything, they should be additionally protected against severe frosts. You can do this e.g. cover with leaves, peat or straw.
Use in the garden
If you want to plant corydaliss in the garden, you need to know which group the species belongs to. Because it depends on where and how it can be used. Especially the polster-forming spring bloomers such as hollowroot-birthwort (Corydalis cava), spring fumewort (Corydalis solida) or transylvanian corydalis (Corydalis transsylvanica) need a slightly sunny to fully shaded area in the garden with humus-rich, moist soil in the garden. You can often find such a location, for example, under deciduous trees and shrubs, which is why they are well suited for planting with corydalis. The bulbous plants can also spend their summer rest undisturbed here. Larger stands of the dainty plants look particularly beautiful.
The perennials can also be socialized with simultaneously blooming lenten roses (Helleborus Orientalis hybrids), lungwort (Pulmonaria) and liverwort (Hepatica nobilis). In order to close the gaps left by the corydalis when it retires after flowering, it can be combined with late-growing perennials such as hostas or astilbe.
The ferny corydalis (Corydalis cheilanthifolia) is used as a wall-greener. With its finely feathered leaves, which take on a copper tone after the fresh green shoots, the short-lived species is suitable for pots and sunny to shady beds. The yellow and white corydalis are also suitable for wall joints and pavement cracks, which – once planted – spread further and further by self-sowing.