Red trillium
Trillium erectum · Melanthiaceae
Dark maroon-red, three-petalled flowers nod above three broad leaves in spring. Its faint smell of wet dog attracts the flies that pollinate it.
- Size
- 16 in tall, 12 in wide
- Zones
- 4 to 7
- Light
- Part shade to shade
- Flowers
- Mid April to mid May
- Pets
- Toxic to people
- Job in a bed
- Drift
A bed built around red trillium
The planner designed this bed around red trillium when this page was made: a 12 × 6 ft (3.7 × 1.8 m) naturalistic planting in zone 6, part shade. It chose the other plants from the 513 that suit those conditions, and says below why red trillium stands where it does.
The plants
- 1 Red trillium × 7, red
- 2 Blue star creeper × 12, blue
- 3 Moor grass 'Greenlee' × 7, tan
- 4 Turtlehead 'Hot Lips' × 3, pink
- 5 Tall astilbe 'Superba' × 3, purple
- 6 Pieris 'Little Heath' × 1, variegated leaves
- 7 Yellow trout lily × 8, yellow
- 8 Hardy cyclamen × 7, pink
Why this plant
- The only open bowls. The others are spires, plumes and bells. Shape reads at a distance, where colours blur.
- The only red.
Why here
- In the middle. At 16 in it is the step between moor grass 'Greenlee' (12 in) in front and pieris 'Little Heath' (2½ ft) behind: each is seen over the one before.
- A step in the back row. Next to pieris 'Little Heath' (2½ ft) and tall astilbe 'Superba' (4 ft): no two neighbours there are the same height, so the back steps up and down like a skyline.
- 7 plants in one group. Massed, one kind reads as a single shape. Scattered, it would look spotty.
Why now
- In flower for five weeks. From mid April to mid May.
- Fills a gap. For one of those weeks nothing else on the plan is in flower.
- Leaves gone by midsummer. They die back and leave bare ground. A perennial that comes up late stands beside it, and grows over the gap.
Planned as a naturalistic planting: low grasses and groundcovers, the matrix, make up 45% of the planted ground. Turtlehead 'Hot Lips' and tall astilbe 'Superba' anchor the back corners of the bed: the tallest plants on the plan stand there. In winter there are still three kinds to look at, blue star creeper and moor grass 'Greenlee' among them.
The planner's own design check: 12 Excellent, 5 Good.
Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.
Where red trillium goes in a border
At 16 in it belongs at the front of a bed. In the planner's ten height classes it is short (12 to 18 in).
Its job: drift. Planted in a small group of three or five, and repeated further along in the other number.
A quieter flower than white trillium, to be discovered and not displayed. It needs cool, acid, leafy soil and does best in northern gardens.
- Native woodland gardens
- Cool, moist, acid shade
- With ferns and other spring wildflowers
What to plant with red trillium
Plants recorded as good partners for it, and what each pairing does:
- Christmas fern: its dark green leaves are a setting for the flowers, before and after.
- Foamflower: in flower together for four weeks, from late April.
- Large-flowered bellwort: in flower together for four weeks, from late April.
Questions about red trillium
Does red trillium need sun or shade?
Red trillium grows in part shade (2 to 4 hours of sun, mostly in the morning) and shade (less than 2 hours of direct sun, or bright dappled light).
It wants ordinary well-drained soil, rich in organic matter, and a good soak in dry spells.
What zones does red trillium grow in?
USDA zones 4 to 7. It is hardy to zone 4, which means it survives winter nights down to about −20 °F (−29 °C).
Above zone 7 it struggles: the zones measure winter cold, but a plant's top zone usually means the summers are too hot or the winters too mild for it to rest.
Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.
When does red trillium flower in my zone?
In zone 5 it flowers mid April to mid May. As a spring flower it moves about a week for every zone: earlier where it is warmer, later where it is colder.
| Zone 4 | Late April to late May |
|---|---|
| Zone 5 | Mid April to mid May |
| Zone 6 | Mid April to early May |
| Zone 7 | Early April to early May |
Worked out from Hopkins' bioclimatic law: spring arrives about four days later for each degree of latitude north, and one zone is roughly two degrees. A warm spring or a cold one moves any garden two weeks either way.
How far apart should red trillium be planted?
12 in (30 cm) apart, from the middle of one plant to the middle of the next. That is about its full width, so each plant keeps its own outline.
It grows 16 in (40 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many red trillium plants do I need?
At 12 in apart, set out in staggered rows:
- 12 to fill 10 square feet (about 1 m²)
- 11 for a single row 10 ft (3 m) long
- 38 to fill a 4 × 8 ft bed on its own
In a mixed border, plant it as a group of three or five, with a second group further along in the other number.
In the bed above, the planner used seven in one group.
Is red trillium poisonous?
Yes: mild toxicity to people. May cause mild stomach upset if eaten.
Rated from NC State Extension. Where references disagree, the more cautious rating is used.
Do deer eat red trillium?
They may. NC State does not list it as resistant to deer or rabbits. Where they visit, protect it, or plant it among ones they avoid.
What flowers after red trillium?
Red trillium is over by mid May. These start as it finishes and carry the same spot on, so it never goes flat:
- Sweet woodruff: from early May to early June, 8 in tall, to stand in front of it and cover its fading stems.
- Lady's mantle: from late May to early July, 18 in tall.
- Columbine: from early May to mid June, 24 in tall.
What does red trillium look like in winter?
Red trillium has long gone by winter: it dies down in summer, soon after flowering, and comes back in spring.
Is red trillium good for bees and butterflies?
Red trillium is visited by pollinators, bees and moths.
It is a host plant: the caterpillars of black-patched clepsis and american angle shades feed on its leaves. A butterfly can only lay its eggs on its host plants, so these do more for it than any nectar flower.
It is native to the United States and Canada.
More Trillium
- White trillium Trillium grandiflorum
In these guides
- Native perennials for pollinators
- Native plants for shade
- Garden plants native to Canada
- Plants for butterflies
- Plants for bees
Every fact on record
- Type
- Perennial
- Size
- 16 in (40 cm) tall, 12 in (30 cm) wide
- Plant
- 12 in (30 cm) apart
- Height class
- Short (12 to 18 in)
- Place in the bed
- Front
- Flowers
- Mid April to mid May; open bowls; red
- Leaves
- Medium texture, summer-dormant; green
- Shape
- Upright, clumping
- Hardy in
- USDA zones 4 to 7
- Light
- Part shade, shade
- Soil
- Rich, well-drained
- Water
- Moderate
- Feeding
- Light, in spring
- Family
- Melanthiaceae
- Comes from
- North America
- Attracts
- Pollinators, bees, moths
- Host plant for
- Black-patched clepsis, American angle shades
Checked against NC State Extension. Flowering times are for zone 5: later in colder zones, earlier in warmer ones. Toxicity and spread information is a general gardening guide, not veterinary or medical advice, and invasive status varies by region. If a person or pet eats a plant, contact poison control or a vet. Check your local invasive species list before planting anything with a spread warning.