perennial

Giant Ironweed

Vernonia gigantea

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Giant Ironweed (Vernonia gigantea) at Weston Nurseries

Giant Ironweed flowers

Giant Ironweed flowers

(Photo courtesy of NetPS Plant Finder)

Plant Height:  6 feet

Flower Height:  8 feet

Spacing:  30 inches

Sunlight:  full sun  partial shade 

Hardiness Zone:  4b

Other Names:  Tall Ironweed

Description:

This variety is right at home in a meadow; long blooming masses of purple flowers sway in the breeze in late summer; may reach ten feet; great for borders or massed as an accent; very undemanding and drought tolerant

Ornamental Features

Giant Ironweed has masses of beautiful ray-like plumes of purple flowers at the ends of the stems from late summer to mid fall, which emerge from distinctive dark red flower buds, and which are most effective when planted in groupings. Its serrated narrow leaves remain green in color throughout the season.

Landscape Attributes

Giant Ironweed is an herbaceous perennial with an upright spreading habit of growth. Its relatively fine texture sets it apart from other garden plants with less refined foliage.

This is a relatively low maintenance plant, and should be cut back in late fall in preparation for winter. It is a good choice for attracting bees and butterflies to your yard. It has no significant negative characteristics.

Giant Ironweed is recommended for the following landscape applications;

  • Accent
  • Mass Planting
  • General Garden Use
  • Container Planting

Planting & Growing

Giant Ironweed will grow to be about 6 feet tall at maturity extending to 8 feet tall with the flowers, with a spread of 3 feet. When grown in masses or used as a bedding plant, individual plants should be spaced approximately 30 inches apart. Its foliage tends to remain dense right to the ground, not requiring facer plants in front. It grows at a fast rate, and under ideal conditions can be expected to live for approximately 10 years. As an herbaceous perennial, this plant will usually die back to the crown each winter, and will regrow from the base each spring. Be careful not to disturb the crown in late winter when it may not be readily seen!

This plant does best in full sun to partial shade. It is quite adaptable, prefering to grow in average to wet conditions, and will even tolerate some standing water. It is not particular as to soil type or pH. It is highly tolerant of urban pollution and will even thrive in inner city environments. This species is native to parts of North America. It can be propagated by division.

Giant Ironweed is a fine choice for the garden, but it is also a good selection for planting in outdoor pots and containers. With its upright habit of growth, it is best suited for use as a 'thriller' in the 'spiller-thriller-filler' container combination; plant it near the center of the pot, surrounded by smaller plants and those that spill over the edges. It is even sizeable enough that it can be grown alone in a suitable container. Note that when growing plants in outdoor containers and baskets, they may require more frequent waterings than they would in the yard or garden.

 
 
Hardiness Zone Plant Height Minimum Sunlight
Characteristics
Accent  Massing  Garden  Container 
Applications
Flowers  Attracts Wildlife 
Ornamental Features