Also known as Knotweed · 55 saves
Polygonum
Polygonum, the genus most gardeners know as knotweed. We track 4 varieties; the ones most used by real gardeners.
The 4 most-saved Polygonum varieties
Species of Polygonum
Each one is a parent of the varieties above.
Track your Polygonum in Sow
Save the Polygonum you grow and get care reminders timed to your zone.
How to grow Polygonum
Whats common across all Polygonum varieties in our catalog — drawn from the care records of the 4 most-grown of them.
The Polygonum year
- PlantMarch, April, May, September and October75% of varieties
Plant containerized or bare-root vines in spring or fall
Do
- Water during dry spells 🌱
- Prune to maintain shape
- Provide support for climbing
- Fertilize monthly during growth
- Water deeply during dry spells 🌱
Avoid
- Overwater to prevent root rot ❌
- Allow plant to become waterlogged
- Neglect pruning
- Plant in poorly drained soil
What goes wrong with Polygonum
| Problem | What you'll see | What to do |
|---|---|---|
| Aphids | Sticky residue and distorted leaves | Use insecticidal soap or neem oil |
| Spider Mites | Fine webbing on foliage, speckled leaves | Use organic insecticidal soap and maintain humidity |
| Root rot | Wilting and blackened roots | Improve drainage and reduce watering |
| Powdery mildew | White powdery coating on leaves | Apply organic neem oil or sulfur-based fungicide |
| Powdery Mildew | White powder on leaves | Ensure good air circulation and apply neem oil |
Making more Polygonum
cuttings
- Select healthy stems in early summer.
- Cut 4-6 inch sections and remove lower leaves.
- Dip in rooting hormone.
- Plant in moist, well-drained soil.
- Keep soil moist for 6 weeks.
division
- Dig up mature plant in early spring.
- Separate root clumps with a sharp knife.
- Replant divisions immediately in prepared soil.
- Water thoroughly after planting.
Polygonum questions
How many types of Polygonum are there?
The Sow catalog tracks 4 distinct Polygonum varieties. The most popular — ranked by 55 real gardeners — are shown first above.
What zones does Polygonum grow in?
Across its varieties, Polygonum covers USDA Zones 4–10. Individual varieties differ — each plant page lists its exact range, and Sow filters the catalog to your zone automatically.
When does Polygonum bloom?
Most Polygonum varieties bloom in summer to fall, mid-summer, late summer. Staggering early, mid, and late varieties extends the genus's season in one bed.
Which Polygonum 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.