Also known as Ironweed · 1.1k saves
Vernonia
Vernonia, the genus most gardeners know as ironweed. We track 16 varieties; the ones most used by real gardeners.
The 16 most-saved Vernonia varieties
6 species of Vernonia
Each one is a parent of the varieties above.
Track your Vernonia in Sow
Save the Vernonia you grow and get care reminders timed to your zone.
How to grow Vernonia
Whats common across all Vernonia varieties in our catalog — drawn from the care records of the 16 most-grown of them.
The Vernonia year
- Spring CleanupMarch and April69% of varieties
Cut back old, dead stems to the ground before new growth begins
- DivideApril and October63% of varieties
Divide large clumps every 3-4 years to maintain vigor
- PruneMay and June44% of varieties
Pinch or cut back stems by 1/3 before mid-June to reduce height and encourage bushiness
- Pinch TipsMay and June38% of varieties
Pinch back stems before June if shorter, bushier plants are desired
Do
- Water deeply during dry spells 🌱
- Deadhead spent flowers to encourage more blooms
- Water regularly to keep soil moist but not waterlogged 🌱
- Apply organic mulch to conserve moisture and suppress weeds
- Cut back in late winter ✂️
Avoid
- Avoid overwatering to prevent root rot ❌
- Overwater to prevent root rot ❌
- Avoid overwatering in winter ❌
- Do not disturb roots during peak flowering
What goes wrong with Vernonia
| Problem | What you'll see | What to do |
|---|---|---|
| Aphids | Sticky residue and distorted leaves | Use insecticidal soap or neem oil |
| Spider mites | Webbing and speckled foliage | Apply insecticidal soap and increase humidity |
| Generally pest-free | No significant insect damage is typical | Monitor only; NCSU rates maintenance as low |
| Deer and rabbits | Nipped stem tips and clipped young leaves on emerging spring shoots. | Apply liquid scent deterrents to young growth early in spring until foliage matures. |
| Powdery mildew | White powder on leaves | Improve air circulation and apply fungicide |
| Powdery Mildew | White powdery coating on leaves, especially in humid conditions with poor air flow. | Ensure good spacing for air circulation. Water at the base of the plant. Apply neem oil as a preventative measure. |
| Root rot | Wilting foliage and soft, darkened root crowns in stagnant, poorly drained water. | Ensure planting sites have adequate drainage and avoid waterlogging roots. |
Making more Vernonia
Division
- Divide clumps in early spring or fall.
- Use a sharp spade to separate root masses.
- Replant immediately for best success.
Seed
- Tuck seeds into moist soil in early spring.
- Cover lightly with soil and keep moist.
- Germination occurs in 2–3 weeks, usually taking 6 weeks for seedlings to establish.
Vernonia questions
How many types of Vernonia are there?
The Sow catalog tracks 16 distinct Vernonia varieties. The most popular — ranked by 1.1k real gardeners — are shown first above.
What zones does Vernonia grow in?
Across its varieties, Vernonia covers USDA Zones 4–9. Individual varieties differ — each plant page lists its exact range, and Sow filters the catalog to your zone automatically.
When does Vernonia bloom?
Most Vernonia varieties bloom in late summer, late summer to fall, late summer to fall. Staggering early, mid, and late varieties extends the genus's season in one bed.
Which Vernonia should I choose?
Start from the most-saved varieties above — popularity across thousands of gardens is a strong signal of reliability — then filter by your zone and sun. In the Sow app you can preview any of them in a photo of your actual yard before you buy.