Helianthus strumosus aka Pale Leaf Sunflower

Helianthus strumosus belongs to the daisy family, Asteraceae. It is a perennial, so it lives for years. People call it paleleaf woodland sunflower or pale-leaved sunflower. It comes from southeastern Canada, including southern Ontario and southern Quebec. It also comes from the central and eastern United States. There, it grows across the Midwest and East. Its range reaches parts of the southern states too. In the wild, it grows in dry woods and on banks.

The plant grows upright to about 6.6 feet [2 metres]. Its roots spread through the soil and may reach beyond beds. This spread can make it invasive in a garden. Its yellow flowers add colour late in the growing season. Chicago Botanic Garden gives July through October as its bloom time. Plants For A Future gives September through October, a shorter span. Each flower has both male and female organs. Bees and flies carry pollen between the flowers. The plant draws birds and butterflies to the garden too.

Sun gives the best match between the sources' growing advice. Chicago Botanic Garden says it can take some shade. Plants For A Future says it dislikes shade. It grows in sand, loam, or clay soil. It likes rich soil that drains well and stays moist. Soil can be slightly acid, neutral, or slightly alkaline. Chicago Botanic Garden lists its water needs as moderate. It also gives USDA zones 3–8. Wild plants grow in dry sites, though garden plants prefer moist soil.

Use this sunflower in borders, planted beds, and sunny woodland edges. Its late flowers add colour after many earlier blooms end. Chicago Botanic Garden says it resists deer. Slugs pose a clear risk to its new shoots. Plants For A Future warns they can kill young plants. To grow it from seed, sow in a cold frame in spring. Keep the young plants under cover through their first winter. Plant them out after the last frost you expect. Split clumps in spring or autumn to make more plants. Put large pieces straight into their final sites. Keep small pieces in pots until their roots take hold.

Plants For A Future says the roots are edible. It gives no firm details on how to prepare them. It also records past use of root preparations as medicine. People used these to treat worms and lung complaints. These records do not show that the treatments work or are safe. The source reports no known hazards. But it gives no specific assessment of safety for pets.