What hardiness zones is Trillium ovatum suitable for?

Trillium ovatum is suitable for USDA hardiness zones 4, 5, 6, 7, 8, 9.

What are the sun requirements for Trillium ovatum?

Trillium ovatum requires Full Shade.

How much water does Trillium ovatum need?

Trillium ovatum has Medium water needs.

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Perennials

Trillium ovatum

western trillium

Melanthiaceae

Southern BC south through Washington, Oregon to northern California, and east to Rocky Mountains; moist coniferous and mixed forest understories

At a Glance

TypePerennial

HabitUpright

FoliageDeciduous

Height8-20 inches (20-50 cm)

Width8-16 inches (20-40 cm)

Maturity10 years

Growing Zones

USDA Hardiness Zones

4 - 9

Zone 4

Zone 5

Zone 6

Zone 7

Zone 8

Zone 9

These zones indicate the coldest temperatures this plant can typically survive.

Frost Tolerancehardy

Key Features

Attracts Pollinators

Fragrant (light)

Native to North America

Maintenancevery low

Overview

A long-lived, deciduous, rhizomatous perennial in the family Melanthiaceae, native to moist coniferous and mixed forest understories from southern British Columbia south through Washington and Oregon to northern California and east to the Rocky Mountains. The specific epithet ovatum means 'egg-shaped,' referring to the shape of the leaves. Plants grow 8–20 inches (20–50 cm) tall in bloom. All vegetative parts occur in threes — a single whorl of three broadly ovate, net-veined, unmottled, sessile leaves 2–7 inches (5–18 cm) long is produced at the top of the unbranched stem. From February through April, a single flower is held above the leaf whorl on a distinct pedicel 0.75–3 inches (2–8 cm) long — this is a PEDICELLATE trillium, meaning the flower has a stalk (distinguishing it from sessile trilliums where the flower sits directly in the leaf whorl). The flower has three green sepals and three pure white petals 1.5–2.5 inches (4–6 cm) long that age progressively to pink and then rose-purple over their 2–3 week lifespan. Mildly toxic: all parts contain saponins and steroidal compounds. WARNING: Do not collect from the wild — western trillium takes 7+ years to flower from seed and wild populations are seriously harmed by picking or digging.

Native Range

Native to moist coniferous and mixed forest understories from southern British Columbia south through Washington, Oregon to northern California, and east to the Rocky Mountains.

Suggested Uses

Planted as a native spring ephemeral in Pacific Northwest woodland gardens and shaded forest understory plantings at 12–18 inch (30–45 cm) spacing — purchase only nursery-propagated stock; never collect from the wild. The February–April white-to-pink-to-rose flowers are among the most celebrated and iconic wildflowers of PNW forests. Combines with Achlys triphylla, Tiarella trifoliata, Maianthemum dilatatum, and Cornus unalaschkensis in native PNW forest understory plantings. Of exceptional educational value — the trinity of threes, pedicellate vs. sessile distinction, flower color change, ant seed dispersal (myrmecochory), and extreme slow growth from seed are all memorable teaching features.

How to Identify

Identified immediately by the TRINITY OF THREES: single whorl of THREE broadly ovate, unmottled, net-veined leaves at stem top; THREE green sepals; THREE white petals. Ovatum = 'egg-shaped' (leaf shape). PEDICELLATE — the flower is elevated on a distinct stalk 0.75–3 inches (2–8 cm) above the leaf whorl. WHITE PETALS AGING TO PINK TO ROSE-PURPLE over the flower's 2–3 week lifespan. Feb–Apr — among the earliest spring bloomers in PNW forest understories. WARNING: Do not collect from wild — takes 7+ years to flower from seed; picking or digging harms populations.

Appearance

Size & Dimensions

Height8" - 1'8"

Width/Spread8" - 1'4"

Reaches mature size in approximately 10 years

Colors

Flower Colors

white

pink

purple

Foliage Colors

green

Fall Foliage Colors

no change

Bloom Information

Bloom Period

~5 weeks

Spring

Blooms February through April for 3–5 weeks — among the earliest native PNW forest wildflowers, often blooming while snow is still present at higher elevations. A single flower per stem, held above the leaf whorl on a distinct pedicel: three pure white petals 1.5–2.5 inches (4–6 cm) long that age progressively to pink then rose-purple over the flower's 2–3 week life. Flowers are lightly fragrant and visited by early-season native bees and flies. Seeds dispersed by ants (myrmecochory) — ants collect seeds attracted by the nutrient-rich elaiosome appendage.

Detailed Descriptions

Flower Description

WHITE aging to PINK to ROSE-PURPLE over 2–3 week lifespan; three petals 1.5–2.5 inches; THREE sepals, THREE leaves, THREE petals; Feb–Apr; lightly fragrant; ant-dispersed seeds (myrmecochory); NEVER PICK — loses season's photosynthesis; ⚠️ mildly toxic: saponins cause GI upset

Foliage Description

medium green; SINGLE WHORL OF THREE broadly ovate unmottled net-veined sessile leaves 2–7 inches at stem top; ovatum = 'egg-shaped'; PEDICELLATE — flower on distinct stalk above leaf whorl; takes 7+ YEARS to flower from seed — DO NOT collect from wild; DATA CORRECTIONS: genus double trailing space; species null

Growing Conditions

Sun Requirements

Partial Shade

Full Shade

Tolerates up to 4 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 7.0(Neutral)

357912

Soil Types

loamclaysiltpeat

Drainage

moist

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

7-10 years

Care & Maintenance

Care Guide

Plant in partial shade to full shade in moist, humus-rich, acidic soil with a pH of 5.5–7.0. Requires consistently moist, humus-rich forest soil conditions — thrives beneath large conifers and hardwoods where duff layers accumulate. Extremely slow-growing from seed (7+ years to first flower); purchase nursery-propagated plants only. Do not disturb once established. Toxicity: all parts contain saponins — can cause gastrointestinal upset if consumed.

Pruning

No pruning. Do not remove the leaves before they yellow naturally — the plant requires full leaf function through summer to build energy for the following year's flower. Allow foliage to die back naturally. Never pick the flowers — a picked flower loses the entire season's photosynthetic capacity and can kill the plant.

Maintenance Level

very low

⚠️ Toxicity Warning

Toxic to humans