Corydalis 'Blue Heron'

Corydalis curviflora var. rosthornii

Family: Papaveraceae (pa-pav-er-AY-see-ee) (Info)
Genus: Corydalis (kor-ID-ah-liss) (Info)
Species: curviflora var. rosthornii
Cultivar: Blue Heron
Additional cultivar information:(aka Heronswood Form)
View this plant in a garden



Water Requirements:

Average Water Needs; Water regularly; do not overwater

Sun Exposure:

Light Shade



Foliage Color:



6-12 in. (15-30 cm)


9-12 in. (22-30 cm)


USDA Zone 4a: to -34.4 C (-30 F)

USDA Zone 4b: to -31.6 C (-25 F)

USDA Zone 5a: to -28.8 C (-20 F)

USDA Zone 5b: to -26.1 C (-15 F)

USDA Zone 6a: to -23.3 C (-10 F)

USDA Zone 6b: to -20.5 C (-5 F)

USDA Zone 7a: to -17.7 C (0 F)

USDA Zone 7b: to -14.9 C (5 F)

USDA Zone 8a: to -12.2 C (10 F)

USDA Zone 8b: to -9.4 C (15 F)

USDA Zone 9a: to -6.6 C (20 F)

USDA Zone 9b: to -3.8 C (25 F)

Where to Grow:

Unknown - Tell us


Parts of plant are poisonous if ingested

Bloom Color:

Dark Blue

Bloom Characteristics:

Unknown - Tell us

Bloom Size:

Unknown - Tell us

Bloom Time:

Late Winter/Early Spring

Mid Spring

Late Spring/Early Summer

Other details:

Unknown - Tell us

Soil pH requirements:

6.1 to 6.5 (mildly acidic)

6.6 to 7.5 (neutral)

7.6 to 7.8 (mildly alkaline)

Patent Information:


Propagation Methods:

By dividing rhizomes, tubers, corms or bulbs (including offsets)

Seed Collecting:

N/A: plant does not set seed, flowers are sterile, or plants will not come true from seed


This plant has been said to grow in the following regions:

Norristown, Pennsylvania

Gardeners' Notes:


On Apr 17, 2015, coriaceous from ROSLINDALE, MA wrote:

This is a difficult plant to grow in my climate (Boston Z6a). I haven't succeeded in wintering it over.

The trick in growing all the blue corydalis is exquisite, rock-garden type drainage, consistent moisture, and protection from strong sunlight.

This species isn't hardy north of Z6, and it hates the hot humid summers of the southeastern US.

The easiest blue corydalis to grow in my climate is the hybrid 'Craigton Blue'.


On Apr 16, 2015, akcrafter from Philadelphia, PA wrote:

I first saw this plant growing vigorously in a Seattle garden. I brought some starts home to Philadelphia, and put them in the ground after researching their needs. They died. I bought nice healthy plants online and tried again. They got smaller and smaller over the season and again died even though I put plants in different areas in my garden. That blue is so beguiling that I am going to try again this year. It is so strange as I have other corydalis, yellow and white, that happily multiply become more and more abundant year by year.

Hopefully, someone will add some comments to help me figure out the problem. I find none in local nurseries, but someone commented here in their success in Norristown, right down the rood from me..


On May 7, 2014, ColoradoLeo from Longmont, CO wrote:

The image posted by anglibet is of Corydalis flexulosa "Blue Panda" - the item I searched for, and found this 'blue heron' entry instead.
I bought this "Panda" one (the second-pictured Corydalis), but it came with no 'instructions' to guide me, and didn't think to check... It did well for a while, but even with watering regularly, when summer full-sun severity overtook it, it dried up. I now know this plant would have done better in a shady, less arid, part of the garden.


On Feb 17, 2006, nifty413 from Garland, TX (Zone 8a) wrote:

It's only been a few weeks since I received this plant from Heronswood, but I'm already impressed. What a marvelous, clear, brilliant blue!! Of course, the real test will be to see whether or not it survives a north central Texas summer!

Updated May 30, 2006: Thought it had entered "summer" dormancy toward the end of last month. Unfortunately, upon closer inspection, the roots have withered and are definitely no longer viable... not at all heat tolerant, it seems. :-(