Also known as Knotweed · 417 gardener saves

Persicaria: the varieties gardeners actually grow

Persicaria, the genus most gardeners know as knotweed. We track 12 varieties; these are the ones gardeners actually save and plant, ranked by real saves rather than catalog marketing. Each links to full care, bloom, and live price data.

12 varietiesZones 4–9Mostly full sun

The 12 most-saved Persicaria varieties

Of 12 in the catalog — ordered by how many gardeners actually grow them.

How to grow Persicaria

What the Persicaria varieties in our catalog actually agree on — drawn from the care records of the 12 most-grown of them, not from a generic template.

The Persicaria year

  • DivideMarch and September100% of varieties

    Divide clumps every 3-4 years in spring or early fall to rejuvenate

  • Spring CleanupFebruary and March83% of varieties

    Cut back old stems to the ground before new growth begins

  • PlantMarch, April, September and October58% of varieties

    Plant in spring or early fall; prefers moist soil

  • MulchMarch50% of varieties

    Apply 2-3 inches of organic mulch to help retain soil moisture

  • DeadheadJune–September50% of varieties

    Remove spent flower spikes to tidy the plant and limit vigorous self-seeding.

  • FertilizeMarch33% 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

ProblemWhat you'll seeWhat to do
AphidsSticky residue and distorted leavesUse neem oil spray or insecticidal soap
SlugsIrregular holes on leavesUse iron phosphate bait or handpick
Spider MitesFine webbing on foliageIncrease humidity and spray with horticultural oil
Powdery MildewWhite powdery coating on leavesImprove air circulation and apply organic fungicide
Root RotWilting and yellowing leavesEnsure well-draining soil and reduce watering
Leaf spotDark spots on leavesRemove affected leaves and improve air circulation

Making more Persicaria

Division

  1. Dig up mature plant in early spring or fall.
  2. Gently separate clumps with a sharp knife or spade.
  3. Replant divisions immediately in prepared soil.
  4. Water thoroughly after planting.
  5. Wait 4–6 weeks for new growth to establish.

Cuttings

  1. Take softwood cuttings in late spring or early summer.
  2. Dip cut ends in rooting hormone.
  3. Plant in moist potting mix.
  4. Keep soil moist and place in bright, indirect light.
  5. Roots develop in about 6 weeks.

Persicaria questions

How many types of Persicaria are there?

The Sow catalog tracks 12 distinct Persicaria varieties. The most popular — ranked by 417 real gardener saves — 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.

Keep exploring

Design with Persicaria in your own yard

Snap a photo of your space and see these varieties planted in it — sized correctly, matched to your zone, with care reminders included.

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