How to Grow and Care for New York Ironweed

New York ironweed is a towering, upright, perennial wildflower native to the eastern and southeastern parts of the United States, where it is commonly found in wet meadows and pastures, stream banks, low-lying woods, and marshes.

This perennial holds appeal to gardeners who prefer native plants. Growing up to seven feet tall, it's popular in wildflower gardens, where, during the growing season, butterflies, bees, and other pollinators flock to it for its nectar. In winter, dead stalks provide sturdy perches for migrating birds.

New York ironweed is a fast-growing, fast-spreading plant normally planted in the spring from potted nursery starts or in the fall from direct-sown seeds. Even when started from seed, it sometimes blooms in its first summer season.

New York Ironweed Care

Like many native wildflowers, ironweed is easy to grow and rarely suffers from serious pest or disease issues. Here are the main care requirements for New York ironweed:

• Plant in rich, moist soil that is slightly acidic.
• Choose a planting site with at least four hours of full sun and ideally with six to eight hours of sunlight.
• Being large plants when mature, space them at least 24 inches apart—they will quickly fill in.
• Provide 1 inch of water per week during the growing season.
• Consider planting New York ironweed as part of a pollinator or butterfly garden as a border plant.

Light

New York ironweed plants prefer full sun but also thrive in partial sun. This plant needs at least four hours of direct sunlight daily but six to eight hours is better. If you live in a colder climate, the plant will prefer as much sun as possible.

Soil

Ironweeds are hardy plants, so they can adapt to many different kinds of soil, though they will naturally thrive in moist, loamy soil that is somewhat acidic in pH. New York ironweed is likely to perish only when planted in extremely barren, dry soil.

Water

Because ironweed prefers moist soil, it will need at least one inch of water per week, and will readily tolerate even more. It will also do well in boggy, poorly draining soils where many other plants struggle.

Temperature and Humidity

New York ironweed readily tolerates the heat and humidity patterns throughout its hardiness range, zones 5 to 9. Where the climate is naturally arid, it may require more ground watering.

Fertilizer

New York ironweed does just fine without supplemental fertilizing during the growing season. Give it a boost by adding a top-dressing of compost in the spring.

Types of Ironweed

In addition to New York ironweed, there are several other species in the Vernonia genus, and some of them are even more popular than New York ironweed as garden plants, especially for colder climates. Some other ironweed species you should consider:

• V. gigantea'Jonesburo Giant': This type grows to as much as 12 feet tall and five feet wide. Deep purple flower clusters appear in autumn. It is hardy in zones 5 to 8.
• V. angustifolia 'Plum Peachy': This is a 42-inch-tall blue-violet variety that is hardy in zones 7 to 9.
• V. lettermannii'Iron Butterfly': This variety has deep purple flowers on short, 3-foot-tall plants. This summer bloomer is hardy in zones 4 to 9.
• V. 'Summer’s Surrender': This is a hybrid cross of V. lettermannii and V. arkansana. It has violet flowers on 4-foot plants and is hardy in zones 4 to 9.
• V. 'Summer’s Swan Song': This hybrid between V. lettermannii and V. angustifolia 'Plum Peachy.' It has violet flowers on 3- to 4-foot plants and is hardy in zones 4 to 9.

Tip

Several Vernonia species are sold as ironweed. Pay attention to the botanical name when purchasing this plant. All ironweeds have similar care needs, but the size and growth patterns differ.

Pruning

New York ironweed requires no pruning, but deadheading spent flowers with pruners is a good idea if you want to limit its self-seeding habit, which can cause the plant to spread aggressively. At the end of the growing season, garden plants can be cut down to near ground level.

Propagating New York Ironweed

New York ironweed should be divided every three to four years to keep the plant healthy and to create new plants to share. Here's how to do it:

1. Dig up the root clump with a shovel in the fall or early spring.
2. Carefully cut away dead parts of the crown and roots with a sharp knife.
3. Cut the leftover crowns and roots into pieces for replanting.
4. Replant the pieces in the desired garden location, leaving 12 to 24 inches of space between pieces.

How to Grow New York Ironweed from Seed

New York ironweed is fairly easy to grow from seeds, either by direct sowing in the garden or starting seeds indoors.

Fall Planting

1. For outdoor direct-seeding, plant the seeds about 1/8 inch deep.
2. Leave seeds to overwinter, and they will germinate and sprout in the spring.

Spring Planting

Start seeds indoors with a period of cold stratification:

1. Plant seeds 1/8 inch deep in flats or pots filled with moistened commercial potting mix, cover them with plastic and refrigerate for about three months.
2. After this time, take the pots out and uncover them, then place them in a warm, bright location until the seeds sprout.
3. When the seedlings are at least 2 inches tall, they can be transplanted into the garden after a hardening off period.

Potting and Repotting

Perennial wildflowers like New York ironweed are not commonly grown in container culture. If you want to try it fill any well-draining container with a general-purpose potting mix.

Potted plants will need more frequent watering. Remember that perennials grown in containers may need some shelter in the winter, as the roots are more exposed to cold than when growing in the ground.

Overwintering

These hardy plants need no special winter protection. Some gardeners like to cut off the dead stalks just above ground level as winter sets in but others leave the stalks and dried flower heads intact to serve as resting/feeding perches for winter birds.

How to Get New York Ironweed to Bloom

It's not uncommon for newly planted specimens to bloom weakly, or not at all, in their first year, especially if soil conditions are less than ideal. Be patient; by the second year, they should bloom vigorously.

Bloom Months

This plant rarely withholds its flowers, which generally appear from midsummer well into fall, from the months of July through September.

What Do New York Ironweed Flowers Look and Smell Like?

New York ironweed's sturdy stems are covered with long, lance-shaped leaves and fluffy deep purple composite flowers, 3 to 4 inches wide, that cluster at the top of the plant from late summer into early fall. Although the flowers are not fragrant, their nectar attracts pollinators.

How to Encourage More Blooms

If a plant does not bloom, it's possible that it is not getting enough sun. If a clump begins to bloom less vigorously, it may be a sign that the plant needs to be dug up, divided, and replanted to rejuvenate it.

Common Problems With New York Ironweed

New York ironweed does not elicit many complaints from gardeners who appreciate native plants and wildflowers. Watch for these two common issues:

Grows Aggressively

This ironweed spreads rapidly and aggressively when growing in a boggy, constantly moist environment. If this becomes a problem, you may need to remove New York ironweed entirely or be prepared to dig out the expanding roots frequently. Other members of the Vernonia genus, especially the hybrids, may be better choices if rampant spread is a concern.

Plants Are Unusually Short

New York ironweed planted in dry soil grows considerably shorter than the 7-plus feet that is normally expected. Increasing the watering volume and intervals may prompt taller growth.

Shorter plants may also be another species in the Vernonia genus. Several native species of ironweed grow only to 3 or 4 feet in height.

From: thespruce