(Silphium perfoliatum) An excellent species to plant for birds and
pollinators. Birds are quick to devour the seeds.
Large leaves surround the square stems to form
little cups that hold rainwater for birds and insects.
Plants grow 5-10' tall on fertile medium soils.
Perennial. Hardy to zone 4.
6-8 weeks before last frost
Green Thumb Tip Sow seeds indoors just beneath surface of soil in
pots or flats. Store flats or pots in refrigerator for
30 days to enhance germination. Keep moist. Plant
seedlings outdoors after danger of frost has passed
and soil is warm. Can also be direct-seeded after
danger of frost has passed.