bog willowherb
Epilobium leptophyllum · Onagraceae
bog willowherb (Epilobium leptophyllum) is a perennial herbaceous plant in the Onagraceae family. It is native to North America. USDA records it as hardy in zone 3 and warmer, down to about -33°F.
⚠ Allelopathic. USDA flags this plant as releasing compounds that can suppress the growth of plants near it. Give neighbours extra room, and expect some companions to struggle regardless of how well their conditions match.
Both flags are quoted from USDA PLANTS, not inferred.
At a glance
| Type | forb-herb USDA |
|---|---|
| Lifecycle | perennial USDA |
| Native status | native USDA |
| Mature height | 3.6 ft USDA |
| Light | part-shade USDA |
| Water need | high USDA |
| Growth rate | slow USDA |
| Soil pH | 4–6.5 USDA |
| Bloom | June–August USDA |
| Flower color | Red USDA |
| Hardiness zones | 3 and warmer USDA |
| Guild layer | herb-layer Derived |
| Nursery availability | No Known Source 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 grows in partial shade. USDA rates it as having needs consistently moist ground. 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 to 6.5 — a broad range that spans acidic through mildly alkaline ground. Its cold limit is zone 3.
Size and growth
At maturity it reaches about 3.6 ft, making it roughly waist to chest height. It grows slowly.
Bloom period
USDA records a bloom period of June through August. Flowers are red.
A flowering date, not a pollinator rating.
Foliage, flower and season
Summer foliage is green, medium in texture. Its flowers are conspicuous. Its active growth period is spring. USDA rates its lifespan as moderate.
What the site needs to provide
USDA records it across sites receiving 15 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 80 frost-free days to finish its season. It roots to at least 10 inches. Fertility requirement: low — no feeding needed on ordinary garden soil.
Propagating it
Propagate it from seed and bare root. USDA records no cold-stratification requirement, so seed should germinate without a chilling period. Its seed spreads at a slow rate. It does not spread vegetatively, so it will stay where you put it.
Resilience and wildlife
Browsing animals find it moderately palatable, so expect deer and rabbits to take an interest. Its fire tolerance is rated none. Its growth form is recorded as single stem.
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 Epilobium
- purpleleaf willowherb Epilobium coloratum
- glaucus willowherb Epilobium glaberrimum
Similar role and hardiness
- common maidenhair Adiantum capillus-veneris
- winter bentgrass Agrostis hyemalis
- European water plantain Alisma plantago-aquatica
- showy milkweed Asclepias speciosa
- butterfly milkweed Asclepias tuberosa
Where this data comes from
Every value on this page comes from the USDA PLANTS database record for symbol EPLE2, 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, Allelopathy, Bloom, Bloom end, 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, Mature height, 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.
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