Also known as Bulbous Persicaria · Curltop Ladysthumb · Curlytop Smartweed
Curlytop Knotweed (Polygonum lapathifolium) is a fast-growing annual herb with lance-shaped leaves and dense spikes of greenish-white flowers, often considered a weed.
At-a-glance light, water, soil, and growing conditions from plant data
Full Sun to Partial Shade
75% intensity
Prefers full sun for best flowering but tolerates partial shade. In very hot climates, some afternoon shade can be beneficial.
Consistent Moisture
75% intensity
Keep soil consistently moist, allowing the top layer to dry slightly between waterings. Avoid waterlogged conditions.
Clay, Loam, Sand, Silty
50% intensity
Adaptable
50% intensity
Grows well in average room temperatures. Tolerates a wide range of conditions.
Aquatic
50% intensity
Low Feeder
25% intensity
Apply a balanced, slow-release fertilizer lightly in spring. Avoid over-fertilizing.
Safety information from plant toxicity data
| Attribute | Value |
|---|---|
| Toxic for humans | No 0/5 intensity |
| Toxic for pets | No 0/5 intensity |
Non-toxic
Key traits and growing stats from plant data
Watering, pruning, propagation, and repotting details from plant data
Polygonum lapathifolium prefers consistently moist soil. Water deeply when the top 2-3 cm of soil feels dry. Avoid waterlogged conditions, which can lead to root rot.
During hot, dry periods, increase watering frequency to maintain soil moisture.
Prune back dead or damaged stems in late winter or early spring before new growth begins. To encourage bushier growth and more flowers, deadhead spent blooms throughout the growing season.
Cut back plants hard after flowering to prevent self-seeding if unwanted.
Polygonum lapathifolium can be easily propagated by seeds sown directly outdoors in early spring or fall. It also readily self-seeds.
Division of established clumps in spring is another effective method, ensuring each section has healthy roots and shoots.
Repotting is generally not necessary for this species as it is often grown as an annual or allowed to self-seed. If grown in a container and it becomes root-bound, repot in spring into a slightly larger pot with fresh, well-draining potting mix.
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Monthly activity intensity for bloom and fruit across both hemispheres.
Flowering & fruiting calendar
Flowering & fruiting calendar
Photos of Curlytop Knotweed (Polygonum lapathifolium)
Where Curlytop Knotweed (Polygonum lapathifolium) is found
Density
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Common names and botanical synonyms
Botanical classification
| Rank | Name |
|---|---|
| Family | Polygonaceae |
| Genus | Polygonum |
| Species | Polygonum lapathifolium |
Similar in genus Polygonum
Answers based on plant encyclopedia data
