rhodora
Rhododendron canadense · Ericaceae
rhodora (Rhododendron canadense) is a perennial shrub in the Ericaceae family. It is native to North America. USDA records it as hardy in zone 4 and warmer, down to about -23°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 | shrub USDA |
|---|---|
| Lifecycle | perennial USDA |
| Native status | native USDA |
| Mature height | 18 ft USDA |
| Light | shade USDA |
| Water need | high USDA |
| Growth rate | moderate USDA |
| Soil pH | 4–5.3 USDA |
| Bloom | April–May USDA |
| Flower color | Purple USDA |
| Hardiness zones | 4 and warmer USDA |
| Guild layer | shrub 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 tolerates full shade. USDA rates it as having needs consistently moist ground. Its drought tolerance is rated low. It will not tolerate waterlogged soil — USDA rates its anaerobic tolerance as none. It is recorded on soils from pH 4 to 5.3 — acidic ground. Its cold limit is zone 4.
Size and growth
At maturity it reaches about 18 ft, making it a small tree or large shrub. It grows at a moderate rate.
Bloom period
USDA records a bloom period of April through May. Flowers are purple.
A flowering date, not a pollinator rating.
Foliage, flower and season
Summer foliage is dark green, coarse in texture. Its flowers are conspicuous. It carries conspicuous autumn colour. Its active growth period is spring and summer. Its winter foliage is dense, which makes it useful for year-round screening. USDA rates its lifespan as long.
What the site needs to provide
USDA records it across sites receiving 35 to 50 inches of annual precipitation. It needs at least 120 frost-free days to finish its season. It roots to at least 16 inches. Fertility requirement: low — no feeding needed on ordinary garden soil.
Propagating it
It takes readily from seed, cuttings, bare root and container stock. Seed needs cold stratification — a period of moist chilling — before it will germinate, so sow in autumn or chill it artificially before a spring sowing. Its seed spreads at a slow rate. It spreads vegetatively at a slow rate.
Resilience and wildlife
Browsing animals rate it barely palatable — the sourced basis for calling it deer-resistant. Its fire tolerance is rated medium, and it can resprout after damage. Its growth form is recorded as multiple stem.
Role in a guild
Shrub layer. In a layered planting this is woody mid-level structure between the understory and the ground. The layer is derived by a fixed rule from growth habit and mature height.
Tags
Related plants
Others in Rhododendron
- Cascade azalea Rhododendron albiflorum
- smooth azalea Rhododendron arborescens
- dwarf azalea Rhododendron atlanticum
- mountain azalea Rhododendron canescens
Similar role and hardiness
- whitethorn ceanothus Ceanothus cordulatus
- yellow rabbitbrush Chrysothamnus viscidiflorus
- coastal sweetpepperbush Clethra alnifolia
- quince Cydonia oblonga
- slender pride of Rochester Deutzia gracilis
Where this data comes from
Every value on this page comes from the USDA PLANTS database record for symbol RHCA6, 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.
Find more plants for your zone with the Plant Finder.