Thalictrum flavum 'Illuminator'
Common Name: yellow meadow rue
Type: Herbaceous perennial
Family: Ranunculaceae
Zone: 5 to 7
Height: 3.00 to 4.00 feet
Spread: 3.00 to 4.00 feet
Bloom Time: May to July
Bloom Description: Yellow
Sun: Full sun to part shade
Water: Medium
Maintenance: Low
Suggested Use: Naturalize
Flower: Showy
Leaf: Colorful
Tolerate: Deer

Culture

Grow in average, medium moisture, well-drained soil in full sun to part shade. Prefers moist, rich, humusy soils in part shade or dappled sun. Needs consistent moisture if grown in full sun. Taller stems may need staking. Some tolerance for hot and humid summer weather. Plants may be cut back after bloom if foliage depreciates. Propagate by seed or division.

Noteworthy Characteristics

Thalictrum flavum, commonly called yellow meadow rue, is a rhizomatous, clump-forming perennial of the buttercup family that typically grows on sturdy stems to 2-3’ (less frequently to 5’) tall. It is native to moist grassy habitats, marshes, ditches, river/stream margins and broad-leaved forests in Europe, the Caucasus and Russia. Compound 2-3 pinnate green leaves feature obovate to elliptic 3-4 lobed leaflets (each to 1 ½” wide). Tiny mildly-fragrant apetulous fluffy yellow flowers (each to 3/8” wide) bloom in summer in branched pyramidal panicles (sparsely leaved compound corymbs) to 2-4” wide. Each flower features pale yellow sepals (usually drop early) plus a showy and conspicuous tuft of abundant bright yellow stamens.

Genus name comes from the Greek word thaliktron which was a name used by Dioscorides to describe a plant in this genus.

Specific epithet from Latin means yellow in obvious reference to flower color.

‘Illuminator’ is a cultivar that features leaves which emerge golden yellow in spring but mature to blue gray by summer.

Problems

No serious insect or disease problems. Powdery mildew, rust, leaf spot and smut are occasional problems. Watch for slugs and snails.

Garden Uses

This perennial is valued for both its attractive foliage and showy yellow flowers. Best in perennial borders, cottage gardens, meadows, open woodland areas or naturalized areas.