Formosa toad lily
Tricyrtis formosana · Liliaceae
Upright stems with glossy leaves, topped by branched clusters of purple-spotted flowers from late summer. It spreads by runners into a colony.
- Size
- 2½ ft tall, 24 in wide
- Zones
- 5 to 9
- Light
- Part shade to shade
- Flowers
- Late August to mid October
- Pets
- No toxicity recorded
- Job in a bed
- Drift
A bed built around Formosa toad lily
The planner designed this bed around Formosa toad lily when this page was made: a 12 × 6 ft (3.7 × 1.8 m) English border in zone 6, part shade. It chose the other plants from the 513 that suit those conditions, and says below why Formosa toad lily stands where it does.
The plants
- 1 Formosa toad lily × 5, purple
- 2 Moor grass 'Greenlee' × 5, tan
- 3 White barrenwort 'Niveum' × 5, white
- 4 Japanese meadowsweet × 3, pink
- 5 Inkberry 'Gem Box' × 1, dark green leaves
- 6 Virginia bluebells × 3, blue
- 7 Yellow trout lily × 12, yellow
- 8 Early crocus × 5, lavender
Why this plant
- The only purple.
Why here
- Anchors a back corner. At 2½ ft it is one of the taller plants here, and the tallest close the ends of the bed, where they stand in front of nothing.
- A step in the back row. Next to Virginia bluebells (20 in): no two neighbours there are the same height, so the back steps up and down like a skyline.
- 5 plants in one group. Massed, one kind reads as a single shape. Scattered, it would look spotty.
Why now
- In flower for 8 weeks. From late August to mid October.
- Closes the season. For its last 7 weeks nothing else on the plan is in flower.
Planned as an English border: 4 of the 5 groups (80%) are drifts, longer along the bed than they are deep. The scheme leans cool (purple, pink, blue and lavender) and uses yellow for warmth, with tan and white to calm things between them. Formosa toad lily and Japanese meadowsweet anchor the back corners of the bed: the tallest plants on the plan stand there.
The planner's own design check: 12 Excellent, 4 Good, 1 Satisfactory. It flags one thing to watch: Nothing on this plan is highly poisonous or an aggressive spreader.
Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.
Where Formosa toad lily goes in a border
At 2½ ft it belongs in the middle of a bed. In the planner's ten height classes it is medium tall (2½ to 3 ft).
Its job: drift. Planted in a small group of three or five, and repeated further along in the other number.
It flowers earlier and for longer than the common toad lily, and carries its flowers at the top of the stems, where they show better.
- A long autumn display in shade
- Groundcover under shrubs
- Cut flowers
What to plant with Formosa toad lily
Plants recorded as good partners for it, and what each pairing does:
- Hosta 'Halcyon': its blue-green leaves are a setting for the flowers, before and after; bold leaves against its medium ones; low enough (18 in) to stand in front of it.
- Japanese painted fern: its silver leaves are a setting for the flowers, before and after; low enough (18 in) to stand in front of it; happy in the same moist soil.
- Yellow waxbells: purple against yellow, opposite each other on the colour wheel, in flower together for six weeks; bold leaves against its medium ones; happy in the same moist soil.
Questions about Formosa toad lily
Does Formosa toad lily need sun or shade?
Formosa toad lily 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 soil that stays evenly moist, rich in organic matter, and a good soak in dry spells.
What zones does Formosa toad lily grow in?
USDA zones 5 to 9. It is hardy to zone 5, which means it survives winter nights down to about −10 °F (−23 °C).
Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.
When does Formosa toad lily flower in my zone?
In zone 5 it flowers late August to mid October. As a summer flower it moves about half a week for every zone: earlier where it is warmer.
| Zone 5 | Late August to mid October |
|---|---|
| Zone 6 | Late August to mid October |
| Zone 7 | Mid August to mid October |
| Zone 8 | Mid August to mid October |
| Zone 9 | Early August to mid October |
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 Formosa toad lily be planted?
18 in (45 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 24 in (60 cm), so a group knits into one patch.
It grows 2½ ft (80 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many Formosa toad lily plants do I need?
At 18 in apart, set out in staggered rows:
- 5 to fill 10 square feet (about 1 m²)
- 7 for a single row 10 ft (3 m) long
- 17 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 five in one group.
Is Formosa toad lily poisonous to dogs and cats?
No toxicity is recorded for dogs, cats, horses or people, according to NC State Extension.
"Not toxic" is not "edible": a pet that eats a lot of any plant can be sick.
Is there a native plant like Formosa toad lily?
Formosa toad lily comes from Taiwan, Nansei-shoto Islands--Ryukyu. These North American natives come closest to doing its job:
- Turtlehead 'Hot Lips': the same job in a bed, the same size and the same flowering time; pink, not purple.
- Blue wood aster: the same job in a bed and the same size; flowers mid September to mid October, lavender, not purple.
- Bottle gentian: the same job in a bed and the same flowering time; 12 in shorter, 6 in narrower.
Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.
Do deer eat Formosa toad lily?
Mostly not. NC State lists it as resistant to deer. No plant is proof against a hungry deer in a hard winter, but this one is low on the menu.
Will Formosa toad lily spread?
It spreads sideways, by runners or roots; the risk of it taking over is moderate. Spreads by underground runners and can crowd its neighbours. Dig out the edges or divide every 2 to 3 years.
What does Formosa toad lily look like in winter?
Formosa toad lily dies down to the ground and there is nothing to see until spring. The old stems can be cut in autumn, or left until spring as shelter for overwintering insects.
Is Formosa toad lily good for bees and butterflies?
Formosa toad lily is visited by bees and hummingbirds.
More Tricyrtis
- Toad lily Tricyrtis hirta
In these guides
- Deer-resistant plants for shade
- Pet-safe plants for shade
- Plants for hummingbirds
- Plants for bees
- Plants that flower in fall
Every fact on record
- Type
- Perennial
- Size
- 2½ ft (80 cm) tall, 24 in (60 cm) wide
- Plant
- 18 in (45 cm) apart
- Height class
- Medium tall (2½ to 3 ft)
- Place in the bed
- Middle
- Flowers
- Late August to mid October; purple
- Leaves
- Medium texture, herbaceous; dark green
- Shape
- Upright, spreading
- Hardy in
- USDA zones 5 to 9
- Light
- Part shade, shade
- Soil
- Rich, evenly moist
- Water
- Moderate
- Feeding
- Light, in spring
- Family
- Liliaceae
- Comes from
- Taiwan, Nansei-shoto Islands--Ryukyu
- Attracts
- Bees, hummingbirds
- Stands up to
- Deer
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.