Siebold's primrose
Primula sieboldii · Primulaceae
Heads of flat, notched or fringed flowers, like snowflakes, in pink, white or lilac, over soft, scalloped leaves.
- Size
- 10 in tall, 12 in wide
- Zones
- 4 to 8
- Light
- Part shade to shade
- Flowers
- Early May to late May
- Pets
- Toxic (mild)
- Job in a bed
- Drift
A bed built around siebold's primrose
The planner designed this bed around siebold's primrose 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 siebold's primrose stands where it does.
The plants
- 1 Siebold's primrose × 3, pink
- 2 Moor grass 'Greenlee' × 11, tan
- 3 Turtlehead 'Hot Lips' × 3, pink
- 4 Tall astilbe 'Superba' × 3, purple
- 5 Inkberry 'Gem Box' × 1, dark green leaves
- 6 Yellow trout lily × 12, yellow
- 7 Grecian windflower × 12, blue
Why this plant
- The only dense clusters. The others are spires, plumes, bells and others. Shape reads at a distance, where colours blur.
Why here
- In the middle. At 10 in it stands ahead of tall astilbe 'Superba' (4 ft) without hiding it.
- 3 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 early May to late 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 an English border: 4 of the 4 groups (100%) are drifts, longer along the bed than they are deep. The back corners are held by turtlehead 'Hot Lips' and tall astilbe 'Superba', the tallest plants on the plan. The scheme leans cool (pink, purple and blue) and uses yellow for warmth, with tan to calm things between them.
The planner's own design check: 10 Excellent, 7 Good. 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 siebold's primrose goes in a border
At 10 in it belongs at the front of a bed. In the planner's ten height classes it is low (6 to 12 in).
Its job: drift. Planted in a small group of three or five, and repeated further along in the other number.
The easiest Asian primrose for an ordinary woodland bed: it survives dry summers by going dormant in July. It creeps slowly into a patch. In Japan it has been bred for centuries.
- Woodland beds in spring
- Planting under deciduous shrubs
- Small-scale groundcover
What to plant with siebold's primrose
Plants recorded as good partners for it, and what each pairing does:
- Japanese painted fern: its silver leaves are a setting for the flowers, before and after; tall enough (18 in) to stand behind it; happy in the same moist soil.
- Hosta 'Blue Mouse Ears': its blue-green leaves are a setting for the flowers, before and after; spires rising out of its mound; happy in the same moist soil.
- Foamflower: in flower together for five weeks, from early May; spires rising out of its mound; happy in the same moist soil.
Questions about siebold's primrose
Does siebold's primrose need sun or shade?
Siebold's primrose 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 siebold's primrose grow in?
USDA zones 4 to 8. It is hardy to zone 4, which means it survives winter nights down to about −20 °F (−29 °C).
Above zone 8 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 siebold's primrose flower in my zone?
In zone 5 it flowers early May to late 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 | Early May to early June |
|---|---|
| Zone 5 | Early May to late May |
| Zone 6 | Late April to late May |
| Zone 7 | Mid April to mid May |
| Zone 8 | Mid 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 siebold's primrose be planted?
10 in (25 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 12 in (30 cm), so a group knits into one patch.
It grows 10 in (25 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many siebold's primrose plants do I need?
At 10 in apart, set out in staggered rows:
- 17 to fill 10 square feet (about 1 m²)
- 13 for a single row 10 ft (3 m) long
- 55 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 three in one group.
Is siebold's primrose poisonous to dogs and cats?
Yes: mild toxicity to dogs, cats and horses. Can cause mild vomiting in pets if eaten.
Rated from the ASPCA. Where references disagree, the more cautious rating is used.
Is there a pet-safe plant like siebold's primrose?
These come closest to doing what siebold's primrose does, and no toxicity is recorded for them:
- Wherry's foamflower: the same job in a bed and the same size; flowers early May to late June, white, not pink.
- Woodland phlox: the same job in a bed, the same size and the same flowering time; blue, lavender or white, not pink.
- Creeping Jacob's ladder: the same job in a bed and the same flowering time; 4 in taller, blue, not pink.
Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.
What flowers after siebold's primrose?
Siebold's primrose is over by late May. These start as it finishes and carry the same spot on, so it never goes flat:
- Lady's mantle: from late May to early July, 18 in tall.
- Astilbe: from late June to mid July, 24 in tall.
- Cranesbill 'Rozanne': from early June to early October, 18 in tall.
What does siebold's primrose look like in winter?
Siebold's primrose has long gone by winter: it dies down in summer, soon after flowering, and comes back in spring.
More Primula
- Cowslip Primula veris
- Drumstick primrose Primula denticulata
- English primrose Primula vulgaris
- Japanese primrose Primula japonica
- Orchid primrose Primula vialii
- Polyanthus primrose Primula x polyantha
In these guides
- Garden plants toxic to cats
- Garden plants toxic to dogs
- Low plants for the front of a border
- Plants for a white garden
Zone guides: Zone 4 · Zone 5 · Zone 6 · Zone 7 · Zone 8
In flower in: May
Every fact on record
- Type
- Perennial
- Size
- 10 in (25 cm) tall, 12 in (30 cm) wide
- Plant
- 10 in (25 cm) apart
- Height class
- Low (6 to 12 in)
- Place in the bed
- Front
- Flowers
- Early May to late May; dense clusters; pink, white, lavender
- Leaves
- Medium texture, summer-dormant; green
- Shape
- Mounding, spreading
- Hardy in
- USDA zones 4 to 8
- Light
- Part shade, shade
- Soil
- Rich, evenly moist
- Water
- Moderate
- Feeding
- None needed
- Family
- Primulaceae
Checked against ASPCA poison lists. 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.