swamp smartweed
Polygonum hydropiperoides · Polygonaceae
swamp smartweed (Polygonum hydropiperoides) is a perennial herbaceous plant in the Polygonaceae family. It is native to North America. USDA records it as hardy in zone 10 and warmer, down to about 32°F.
At a glance
| Type | forb-herb USDA |
|---|---|
| Lifecycle | perennial USDA |
| Native status | native USDA |
| Light | full-sun USDA |
| Water need | medium USDA |
| Growth rate | slow USDA |
| Soil pH | 4.5–8.8 USDA |
| Flower color | Green USDA |
| Hardiness zones | 10 and warmer USDA |
| Guild layer | herb-layer Derived |
| Nursery availability | Routinely Available USDA |
USDA quoted from the USDA PLANTS database · Derived computed by a fixed rule from those columns. No value on this page is estimated.
Growing conditions
It needs full sun. USDA rates it as having moderate water needs. Its drought tolerance is rated low. It tolerates saturated, poorly drained ground well (USDA rates its anaerobic tolerance high). It is recorded on soils from pH 4.5 to 8.8 — a broad range that spans acidic through mildly alkaline ground. Its cold limit is zone 10.
Size and growth
It grows slowly.
Foliage, flower and season
Summer foliage is dark green, fine in texture. Its flowers are not conspicuous — a plant for form and foliage. Its active growth period is summer. USDA rates its lifespan as moderate.
What the site needs to provide
USDA records it across sites receiving 12 to 50 inches of annual precipitation. The low end of that band is genuinely arid, so it has a wide tolerance for dry country. It needs at least 95 frost-free days to finish its season. It roots to at least 10 inches. Fertility requirement: medium.
Propagating it
Seed is the only propagation method USDA lists. Division and cuttings are not listed as options. USDA records no cold-stratification requirement, so seed should germinate without a chilling period. Its seed spreads at a moderate rate. It does not spread vegetatively, so it will stay where you put it.
Resilience and wildlife
Browsing animals rate it barely palatable — the sourced basis for calling it deer-resistant. Its fire tolerance is rated medium. Its growth form is recorded as single crown.
Role in a guild
Herb layer. In a layered planting this is the herbaceous middle — perennials and grasses that fill the space between ground cover and shrubs. The layer is derived by a fixed rule from growth habit and mature height.
Tags
Related plants
Others in Polygonum
- water knotweed Polygonum amphibium
- meadow bistort Polygonum bistorta
- American bistort Polygonum bistortoides
- Davis' knotweed Polygonum davisiae
Similar role and hardiness
- pineapple Ananas comosus
- clasping coneflower Dracopis amplexicaulis
- Indian blanket Gaillardia pulchella
- jewelweed Impatiens capensis
- Bigelow's tansyaster Machaeranthera bigelovii
Where this data comes from
Every value on this page comes from the USDA PLANTS database record for symbol POHY2, or is computed from those values by a fixed rule. Nothing here is estimated or model-generated. Where USDA publishes no value, this page omits the claim rather than filling the gap.
- Quoted from USDA PLANTS: active growth period, browse palatability, cold stratification, Drought tolerance, fall conspicuous, fertility requirement, fire tolerance, Flower color, flower conspicuous, foliage color, foliage porosity winter, foliage texture, frost free days min, fruit conspicuous, growth form, Growth rate, Hardiness zones, Lifecycle, lifespan, Light, Minimum temperature, Native status, Nitrogen fixation, Nursery availability, precipitation max in, precipitation min in, propagation, resprout ability, root depth in, seed spread rate, Soil pH, Soil pH (upper), Tolerance of wet soil, Toxicity, Type, vegetative spread rate, Water need.
- Derived by a fixed rule from those columns: Guild layer.
Read our full data sources and methodology.
Find more plants for your zone with the Plant Finder.