New York Ironweed – Facts, Identification, Growing Info
November 7, 2019
New York Ironweed is a herbaceous perennial wildflower with dark purple-to-pink blooms native to Eastern North America. Blooming in late summer to early fall, this tall plant will draw in the butterflies with its tubular flowers. I often see this plant growing in ditches and along roadsides. But you can also find it in open woods, clearings, anywhere moist that gets at least partial sun.
The Scientific Name of New York Ironweed is Vernonia noveboracensis
This is a tall, erect herbaceous perennial flower that is typically around 5-6′ tall (1.5-1.8 m), but can range from 4-8′ depending on conditions. It generally can stay vertical and will not flop over, which is a nice benefit in a garden.
Stalk / Stem
The stalk is stiff and green, normally reaching heights of 5-6′. There will not be any branches until the last 6″-12″ of stalk, where it will make branches into a panicle to produce flowers.
The leaves are large, from 3-12″ long. Leaves of NY Ironweed are generally lance-shaped to oblong / oval, almost resembling a spear tip. They are alternate along the stalk.
There will be many flowers heads along the panicle at the top of the plant. The size of the flat-top cluster of flowers is roughly 6″-12″ (15-30 cm). There will be numerous small purple-to-reddish purple, or even pink colored blooms.
This plant has short rhizome roots and fibrous roots. Small colonies are formed through the short rhizomes, but it isn’t too aggressive.
New York Ironweed will grow well in full sun to partial shade. I’ve observed it in both conditions, as they grow in the ditches, and the available sunlight seems to have a large effect on the final height. In general though, this plant likes moist to medium moisture soil. As far as soil types, it can grow well in loam and clay (yes, clay). It may have trouble in sandy soil if it drains too much. However, I have seen this plant to just fine in drought conditions, as roadside ditches experience drought the same as anywhere else.
How to care for
As with most plants, the best way to care for them is to plant them in their preferred growing conditions! Give it partial-full sun (4-6 hrs per day), and moist spot in the garden and it should do just fine.
You can cut the plant back in Spring after insects have emerged from dormancy. But other than that, no maintenance is really required. If you feel that your plants grow too tall, you can cut them back in late Spring to reduce the final height.
How to Establish New York Ironweed
Plant Ironweed seedlings in the early Spring or Late Fall before the ground is frozen. In that way, the roots will have plenty of time to get established while there is little water demand from the plant. This is because the cooler temperatures allow the plants to grow without using water to cool themselves.
How to Grow Iron Weed from Seed
Ironweed is somewhat difficult to establish from seed. The trouble is, the seed from Ironweed may need to be refrigerated to stay viable. Furthermore, I think fresh seed must be sown, and you cannot store it year to year.
So, you collect some seed – dry it, then refrigerate it in a sealed container. Then finally you can stratify it for probably 2-3 months, or just winter-sow it. I generally plant it anywhere from 0-6 mm. I’ve found that most of the seed doesn’t seem to be viable when starting in pots, as my germination rate has been very low.
The best success I’ve had with this plant was direct sowing in fall, right after seed collection. I got approximately 5-6 plants to grow to seedling form, and a couple even bloomed the first year. But the time to germination was loooong.
Ironweed Garden Uses
This plant can be excellent at the back of a well manicured flowerbed. Its tall and erect stature will provide a late summer / early fall wall of purple blooms that is long lasting. Also, Ironweed is a perfect plant for a rain garden. It loves moisture (but not flooding), and does great in partial shade. Just make sure it doesn’t block the view of other plants. So, put it in the back, or as a central focal point to walk around.
It can be an integral part of a moist micro prairie, or even in just a ‘moist part’ of one. We grew about 5 seedlings this year from direct sowing in the previous fall. We were even treated to a single bloom! I think a certain herbivore species decided they needed to trim these off for us (more on that later).
Side note – click below to see how to make your own backyard Micro-prairie!
New York Ironweed would grow well with other moisture loving, partial shade to full sun plants. Placing a layered flower bed with Ironweed in the back, Swamp Milkweed in front, and Blue Lobelia in front of that would be striking from July through September. Adding in some Virginia Bluebells would further provide color for almost the whole year.
This plant is a host to numerous moth caterpillars. The foliage is also eaten by other insects and aphids. Flowers are beloved by bees, butterflies, and skippers.
Pests and diseases
Ironweed generally does not get diseases.
For deer/rabbits, most references you will find list this plant as being deer resistant. In my experience, deer will browse this plant. It was quite frustrating, but I lost the tops of plants (where the flowers were), and I assume they were deer. I don’t think it was rabbit damage, as they generally consume the whole plant, or just snip off the top and leave it laying beside the plant.
NY Ironweed Reference Table
New York Ironweed
Late Summer / Early Fall
Approximately six weeks
Dark Purple to Pink
Cluster of small flowers 6-12” diameter (15-30 cm)
A cluster of small individual flowers, on small branches forming a panicle
3’ spread (1 m)
Full Sun / Partial Shade
Moist to Medium
None. Cut back in Spring after insects have emerged
Meadow, prairie, roadside
Caterpillars and other insects feed on foliage
0-1/8” (0-3 mm)
60 days cold stratification. Or direct sow in Autumn/Winter – You need fresh seed!
USDA Zones 5-9
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Hi - I grew up outdoors in nature - hiking, fishing, hunting. In high school I got my first job at a garden center where I learned to garden and landscape. I've been growing plants from seed and designing native plant gardens for over six years. I hope to share some of my knowledge with you!
Additionally I am a wood worker / DIY enthusiast. I enjoy designing/building projects (with hand tools when I can!). I hope to give you some tips and useful information!