Large-flowered trillium Trillium grandiflorum
Large-flowered trillium (Trillium grandiflorum) is a deciduous perennial flowering plant in the Melanthiaceae family, native to Eastern North American deciduous forest (emblem of Ontario). It grows 25–45 cm (10–18 in) tall and 20–30 cm (8–12 in) wide, wants shade and moderate water, and is hardy to about -37 °C (-35 °F). Space plants about 25 cm (10 in) apart.
Plan Large-flowered trillium in your garden →
Free. Draw your beds, then watch it grow through the year in 2D and 3D.
Large-flowered trillium at a glance
| Type | Perennial flowering plant, deciduous |
|---|---|
| Family | Melanthiaceae |
| Mature height | 25–45 cm (10–18 in) |
| Mature spread | 20–30 cm (8–12 in) |
| Spacing | 25 cm (10 in) centre to centre |
| Sun | Shade, at least 2 h of direct sun a day |
| Water | Moderate; drought tolerance low, waterlogging tolerance low |
| Soil pH | 5.5–7 |
| Cold hardiness | About -37 °C (-35 °F) once established (roughly USDA zone 3) |
| Heat stress | Likely above about 30 °C (86 °F) |
| Flowering | from about April for 3–4 weeks (northern hemisphere; later in cold climates, earlier in warm ones) |
| Wind tolerance | Low |
| Pollinator value | Moderate |
| Edible | Not grown as food |
| Native to | Eastern North American deciduous forest (emblem of Ontario) |
| Common in gardens of | 🇺🇸 United States |
Is Large-flowered trillium toxic?
- People: mildly toxic
- Cats: mildly toxic
- Dogs: mildly toxic
- Parts: berries, rhizome
Saponins; may cause vomiting.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Large-flowered trillium
No well-documented helpful pairing. Group it with plants that like shade and moderate water.
See Large-flowered trillium in a botanical garden
It grows in these sample gardens, which you can walk through in 3D:
- UC Botanical Garden, Berkeley (10 plants)
- Brooklyn Botanic Garden (8 plants)
- The Butchart Gardens (8 plants)
- Missouri Botanical Garden (8 plants)
- New York Botanical Garden (10 plants)
- Jardin botanique de Montréal (10 plants)
Questions about Large-flowered trillium
- How far apart should I plant Large-flowered trillium?
- About 25 cm (10 in) apart, centre to centre. A mature plant spreads 20–30 cm (8–12 in).
- Does Large-flowered trillium need full sun?
- Shade: at least 2 hours of direct sun a day.
- How much water does Large-flowered trillium need?
- Moderate water. Drought tolerance is low and waterlogging tolerance low.
- How cold-hardy is Large-flowered trillium?
- It tolerates about -37 °C (-35 °F) once established, roughly USDA zone 3.
- When does Large-flowered trillium flower?
- From about April for 3–4 weeks (northern hemisphere; later in cold climates, earlier in warm ones).
- Is Large-flowered trillium poisonous to cats and dogs?
- For cats it is mildly toxic; for dogs mildly toxic; for people mildly toxic. Saponins; may cause vomiting.
- What grows well with Large-flowered trillium?
- There is no well-documented companion pairing for Large-flowered trillium. Group it with plants that like the same sun (shade) and water (moderate).
Sources and evidence
Evidence grade B (B: extension service or peer-reviewed).
- Missouri Botanical Garden Plant Finder, Missouri Botanical Garden
- USDA PLANTS Database, USDA NRCS
Notes and assumptions
- Three leaves, three white petals that age pink; takes 7+ years from seed to flower; ants disperse the seeds.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
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- French marigold Tagetes patula
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- Cosmos Cosmos bipinnatus
- Purple coneflower Echinacea purpurea
- Foxglove Digitalis purpurea
- Daffodil Narcissus pseudonarcissus