On a bright late summer day, the purple flowers of ironweed glow. Ironweeds can take their place in sunny moist beds and borders, rain gardens, and beside ponds and streams. In limited space, cut the stems by half in early summer to control height. They are magnets for butterflies.
Late Summer Star
Standing 4 to 6 feet tall at maturity, ironweed boasts a big garden presence when it begins blooming in late summer. That's because clusters of bright purple flowers decorate its tall stems for 6 weeks or more at the end of the growing season. Ironweed received its common name from its ironlike qualities: tough stems, tenacious growing habit, and flowers that give way to seed clusters the color of rust.
Ironweed provides nectar loved by pollinators: long-tongue bees, flies, skippers, and butterflies such as monarchs, swallowtails, and American painted ladies. It also provides a food source for caterpillar moths.
Create an oasis for these vital members of our ecosystem by planting ironweed alongside other pollinator plants: goldenrod, giant hyssop, prairie blazing star, smooth blue aster, and Culver's root, for example. In addition to planting for pollinators, you can enhance your backyard habitat by eliminating the use of pesticides. Control weeds through mechanical removal, soil cultivation, and thick layers of mulch that choke unwanted plants.
How to Grow Ironweed
Low-maintenance ironweed grows best with full sun and rich, moist almost acidic soil . Sunny, moist beds and borders, rain gardens, low areas, and stream banks suit it well. This perennial also thrives in casual cottage gardens, native prairie gardens, meadows, and other naturalized areas. Ironweed's bitter foliage makes it undesirable to most grazing animals, so it is considered a weed in pasture plantings.
Ironweed spreads readily through self-seeding. Limit its spread by snipping off flower heads before the seeds develop. Reduce the overall height of mature plants in late spring by cutting young stems back almost to the ground.
Plant Ironweed With:
Joe Pye weed is a showstopper of a prairie native, producing huge, puffy flower heads in late summer. It prefers moist soils, but with its extensive root system, it also tolerates drought well. It is a large plant, growing 4 to 6 feet tall.Closely related, hardy ageratum is a spreading plant that grows to only 2 feet tall. Another relative, white snakeroot, reaches 4 to 5 feet tall. All are great for naturalistic or cottage plantings and for attracting butterflies.
A big, bodacious, beautiful plant, perennial sunflower is imposingly tall and floppy with large (up to 4-inch), bright yellow flowers that form in loose clusters. Most of these natives thrive in full sun and are not fussy about soil. The taller ones may need support. Excellent for cut flowers.
Asters get their name from the Latin word for "star," and their flowers are indeed the superstars of the fall garden. Some types of this native plant can reach up to 6 feet with flowers in white and pinks but also, perhaps most strikingly, in rich purples and showy lavenders.Not all asters are fall bloomers. Extend the season by growing some of the summer bloomers, as well. Some are naturally compact; tall types that grow more than 2 feet tall benefit from staking or an early-season pinching or cutting back by about one-third in July or so to keep the plant more compact.