Virtues:Corydalis lutea, or yellow corydalis, adds soft texture to the garden with its fern-like foliage. Its frothy bright yellow flowers appear in late spring and can continue through the summer. This perennial’s tolerance of shade makes it a good candidate for brightening dark corners of the garden.
Common name: Yellow corydalis, yellow fumitory
Botanical name:Corydalis lutea
Exposure: Part sun to full shade
Season: Spring to fall for foliage; late spring onward for flowers
Flowers: Beginning in late spring, short spikes rise above the leaves, holding small but numerous bright yellow tassel-like blossoms. When Corydalis lutea is happy, it can continue to bloom lightly through summer and into fall.
Foliage: The medium green leaves resemble the foliage of maidenhair fern.
Habit:Corydalis lutea grows about 10 to 15 inches tall with a similar spread. It has a mounded shape that can fill a corner, provide edging around a bed of taller, more upright perennials and shrubs or cascade gently atop a retaining wall.
Origins: This corydalis is native to Europe.
How to grow Corydalis lutea: Site in part sun to full shade and average soil with good drainage. Yellow corydalis prefers evenly moist soil and will not tolerate drought; supplemental watering will be necessary in dry spells. This perennial does not like high heat and high humidity, but in moderate summer temperatures it performs very well and requires little input.
For a special effect, it can be grown atop a stone wall or in the pockets of the wall, positioning that provides the good drainage it requires. The stones also regulate the soil temperature and keep it from dry out too completely or too quickly. Yellow corydalis also serves well as a ground cover in the shade or as an edging to shady borders containing taller shrubs and plants, thanks to its rounded shape and fine yet dense foliage.
Corydalis lutea can self-sow aggressively if it is growing and flowering well. To avoid unwanted seedlings in this situation, shear off the spent flowers before they go to seed. However if ground coverage through naturalizing is desired, this plant can be a good choice particularly in shade. USDA Zones 5–7.
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Bottom (detail): Mantonature / iStock / Getty Images