Corydalis Plant Profile

Tubular pale blur flowers and lacy reaves with deep red stems.

Sonya / Flickr / CC BY 2.0

This plant's name comes form the Greek meaning "crested lark" due to the birdlike shape of its flowers. Indeed, one of the most popular cultivars is called "Blue Heron." They are deer resistant, and while they self-sow readily, they are non-invasive. They are also useful food plants for the larvae of many butterflies. There are more than four hundred different species of corydalis; most are native to the temperate regions of the Northern Hemisphere and the most diversity of species is found throughout China and Asia and the mountainous regions of northeast Africa.

The corydalis is in the poppy family, but also somewhat related to the dicentra (bleeding heart). It has a number of medicinal uses, for pain relief and circulation issues, among other applications. They have been used in various herbal medicine traditions in Europe, India, and China for centuries. In North America, it also has a history of being used medicinally by Native Americans, and the folk names include turkey corn or squirrel corn, after the bumpy tubers, which are the part used for medicine. In addition to being a useful medicinal plant, the flowers fairly early in spring and so are valuable in the garden landscape for early spring color that persists through summer. The flowers are quite small and delicate with an unusual curving tubular or trumpet shape. Corydalis come in a range of colors depending on variety, from pink to purple to blue, and some white and yellow.

Botanical Name Corydalis canadensis
Common Name Fumewort, hollow wort, turkey corn
Plant Type Perennial
Mature Size 12 to 18 inches
Sun Exposure Shade to partial sun
Soil Type Rich, well-drained, slightly alkaline
Soil pH 5.0 - 7.0
Bloom Time Spring
Flower Color Blue, pink, purple, white, yellow
Hardiness Zones 5 to 7
Native Areas China, Northern Africa, Northern Hemisphere
Yellow tubular flowers and lacy green leaves.
Corydalis lutea has delicate yellow flowers. Carmen Pa​ixao / Flickr / CC BY 2.0

How to Grow Corydalis

These colorful flowers grow happily in a shade garden or woodland setting. They're reliable bloomers with flowers appearing over several months beginning in spring, and their lacy foliage remains attractive throughout a long season. Deadhead the flowers to keep the plants looking neat and to keep foliage healthy. Some varieties may have a tendency towards more evergreen foliage. The plants self-sow and spread fairly quickly, so divide the clumps every few years to keep them under control as needed.

Light

Corydalis are shade lovers, and useful to brighten up shady spots in your garden with color. They can tolerate some sun, but afternoon sun would probably be too much for them, especially in zone 7 during hotter summer temperatures.

Soil

Corydalis flowers like a rich well-drained soil that is not too moist. The roots can be subject to root rot if soil stays too wet, and if your corydalis does not overwinter, either you live in a zone that is too cold (below 5) and/or the soil is too wet and the roots stay frozen.

Temperature and Humidity

Plant corydalis in a cool shady spot. Basic temperate humidity is appropriate for these naturalizing shade plants. These flowers are somewhat fussy about temperature and will not survive in growing zones lower than 5 or higher than 7.

Propagation

Corydalis can be propagated by seed, division or separating plants. They self-sow readily, so one suggestion is to ask a gardening friend for a division of them! Most yards wth corydalis growing should have plenty to spare. Or get some fresh seed, as packaged seed does not to tend to germinate as well. Collect seed in the fall, plant in containers and the plants should germinate in spring.

Toxicity

There is a danger of various side effects when using corydalis medicinally, including nausea, dizziness or vertigo. There is also a risk of associated with one of the plant's main constituents: tetrahydropalmatine (THP) toxicity can cause acute hepatitis, an inflammation of the liver that can cause vomiting, fever and abdominal pain. Only use this plant medicinally under the recommendation of a certified professional. Corydalis growing in the wild has been known to be toxic to livestock when it proliferates in grazing areas, so this needs to be addressed to keep farm animals from ingesting too much of it when grazing. Although rare, it is also possible for dogs to become ill from ingesting corydalis. The best way to prevent your dog from ingesting the plant is to keep an eye on your pets in your yard and on walks to make sure they're not eating anything they shouldn't. Having some oat grass available will help satisfy your dog's craving for greens.