Vernonia sp. (Ironweeds)

Zone: 4 to 8

Soil: sand to clay

Light: Full sun to part sun

Bloom colour: Purple

Bloom period: August to September

Height: 4 to 10 feet

Moisture: Usually medium to moist

Attracts: A variety of bees and butterflies.

Notes: The members of this genus are widely available at nurseries

Vernonia is a late season plant. It takes so long to emerge that you may well think it has died during the winter. Give it at least until the beginning of June. After these plants emerge, they grow quickly to become one of the tallest plants in the garden. These plants are moderately attractive to bees and butterflies. Two species are native to Ontario. Vernonia missurica and Vernonia gigantea. A third species, Vernonia noveboracensis, is also native to the North East, but not in Canada. Typically, this genus does well in average to moist soil. New York ironweed can handle clay and a fair amount of shade. It grows up to 10 feet in height.

The Canadian species mentioned are similar in appearance and grow to about 5 to 6 feet high. They can hybridise. Missouri Ironweed is the more attractive of the two Canadian species while giant ironweed is more shade tolerant. Both species show some drought tolerance. The flowers are all deep purple in colour and are located at the top of the plant. Since the leaves are not outstanding in any way, it is better to plant them at the back of the border behind other plants. If you prefer plants that are only about 4 feet tall, then hack them down by half at the end of June as flowering will only be delayed by a few days.

Vernonia noveboracensis - New York Ironweed
Vernonia missurica
Vernonia missurica-Missouri Ironweed
vernonia with resin bee
Vernonia with a Giant Resin Bee. This bee is a large leafcutter bee that has been introduced from Asia. They may impact Carpenter bees by competing with them for shelter.