Eutrochium maculatum Seeds | Spotted Joe-pye Weed
LATIN NAME: Eutrochium maculatum
COMMON NAME: Spotted Joe-Pye Weed
Plant Profile
Spotted Joe-Pye weed is a tall perennial of wet meadows and riverbanks in eastern North America, growing one and a half to two and a half metres on sturdy, purple-blotched stems. The leaves are arranged in whorls of three or four, lance-shaped and rough to the touch, and they smell faintly of vanilla when bruised. In late summer the stem ends in a broad, domed head of small, dusty pink flowers that darken as they age and that are worked by more butterfly species than almost any other native plant of the region. The seed heads persist into winter and feed goldfinches. The plant dies back to a woody crown each autumn and returns late, so it needs patience in spring. It is a plant of damp ground, not of dry borders.
Science & Biotechnology
Eutrochium maculatum was long placed in Eupatorium, and the split of the North American species into a separate genus in 2000 was based on chromosome counts and on the structure of the flower head. The species is a polyploid complex, with diploid, tetraploid and hexaploid populations that differ in size and in leaf shape, which is one reason the taxonomy has been so messy. Its flowers produce both nectar and pollen in quantity, and studies of pollinator visitation in wet meadows consistently rank it among the top three herbaceous plants for butterfly diversity. The vanilla scent comes from coumarin, released when the leaves are crushed. The plant is also a larval host for the larvae of several moths, and its hollow stems are used as winter shelter by small bees.
Uses & Benefits
The plant is grown in rain gardens, meadow plantings and the back of a moist border, where its height and late flowers extend the season into September. It is one of the best plants for a pollinator garden in a damp spot, and it pairs well with ironweed, joe-pye’s usual neighbour in the wild. In folk medicine the root was used as a diuretic and for joint pain, and it appears in nineteenth-century American herbals under several names, though it has no place in modern practice. The dried flower heads are useful in winter arrangements. It is not a plant for a small border or dry soil, and it flops in shade, so give it sun and moisture and it will stand without staking.
Growing from Seed
Fresh seed gives the best stand; stored seed thins out fast. Mix it with damp sand and keep at four degrees for eight to twelve weeks, then surface-sow on a moist seed mix and press it in, since light helps. Keep at twenty degrees; germination takes two to four weeks. The seedlings are slow at first and should be grown on in deep pots, because the root system is substantial. Plant out in spring into moist, humus-rich soil in full sun, and water well through the first season. Space plants sixty centimetres apart. Cut the stems back to fifteen centimetres in late winter, and divide the clumps every four years to keep them vigorous. Stake only in exposed sites.
Our Take
The best late-summer butterfly plant of the American east, and it needs wet feet. Give it sun, space and no drought.
Related Reading
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