Also known as Knotweed · 451 saves
Persicaria
Persicaria, the genus most gardeners know as knotweed. We track 15 varieties; the ones most used by real gardeners.
The 15 most-saved Persicaria varieties
5 species of Persicaria
Each one is a parent of the varieties above.
Track your Persicaria in Sow
Save the Persicaria you grow and get care reminders timed to your zone.
How to grow Persicaria
Whats common across all Persicaria varieties in our catalog — drawn from the care records of the 15 most-grown of them.
The Persicaria year
- DivideApril and October87% of varieties
Divide clumps every 3-4 years in spring or early fall to rejuvenate
- Spring CleanupMarch and April87% of varieties
Cut back old stems to the ground before new growth begins
- PlantApril, May, October and November53% of varieties
Plant in spring or early fall; prefers moist soil
- DeadheadJuly–October47% of varieties
Remove spent flower spikes to tidy the plant and limit vigorous self-seeding.
- MulchApril33% of varieties
Apply 2-3 inches of organic mulch to help retain soil moisture
- FertilizeApril33% of varieties
Apply a balanced, slow-release fertilizer in early spring
Do
- Water regularly to keep soil moist 🌱
- Water regularly to keep soil moist but not waterlogged 🌱
- Water consistently to keep soil moist 🌱
- Prune after flowering to maintain shape
- Provide full sun for optimal flowering
Avoid
- Avoid letting soil dry out completely ❌
- Avoid overwatering to prevent root rot ❌
- Don’t fertilize in late fall
- Never cut back in late season to prevent winter damage
What goes wrong with Persicaria
| Problem | What you'll see | What to do |
|---|---|---|
| Aphids | Sticky residue and distorted leaves | Use neem oil spray or insecticidal soap |
| Slugs | Irregular holes on leaves | Use iron phosphate bait or handpick |
| Spider Mites | Fine webbing on foliage | Increase humidity and spray with horticultural oil |
| Spider mites | Fine webbing on leaf undersides and yellow stippling on the foliage. | Apply a strong spray of water to knock mites off, or use insecticidal soap if infestations persist. |
| Powdery Mildew | White powdery coating on leaves | Improve air circulation and apply organic fungicide |
| Root Rot | Wilting and yellowing leaves | Ensure well-draining soil and reduce watering |
| Powdery mildew | White powder on leaves | Improve air circulation and apply neem oil |
Making more Persicaria
Division
- Dig up mature plant in early spring or fall.
- Gently separate clumps with a sharp knife or spade.
- Replant divisions immediately in prepared soil.
- Water thoroughly after planting.
- Wait 4–6 weeks for new growth to establish.
Seed
- Tuck seeds into moist soil in early spring, 6 weeks before last frost.
- Maintain soil moisture until germination occurs.
Persicaria questions
How many types of Persicaria are there?
The Sow catalog tracks 15 distinct Persicaria varieties. The most popular — ranked by 451 real gardeners — are shown first above.
What zones does Persicaria grow in?
Across its varieties, Persicaria 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 Persicaria bloom?
Most Persicaria varieties bloom in late summer, mid-summer to fall, summer to fall. Staggering early, mid, and late varieties extends the genus's season in one bed.
Which Persicaria 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.