Snowmound spirea
Spiraea nipponica 'Snowmound' ·
Arching branches lined along their whole length with small, white flower clusters in late spring, over small, blue-green leaves.
- Size
- 4 ft tall, 5 ft wide
- Zones
- 4 to 8
- Light
- Full sun
- Flowers
- Late May to early June
- Pets
- No toxicity recorded
- Job in a bed
- Anchor
A bed built around snowmound spirea
The planner designed this bed around snowmound spirea when this page was made: a 16 × 8 ft (4.9 × 2.4 m) English border in zone 6, full sun. It chose the other plants from the 966 that suit those conditions, and says below why snowmound spirea stands where it does.
The plants
- 1 Snowmound spirea × 1, white
- 2 Sedum 'Lidakense' × 45, pink
- 3 Sea thrift × 11, pink
- 4 White mugwort × 3, cream
- 5 Wild quinine × 5, white
- 6 Little bluestem × 3, blue-green leaves
- 7 Gloriosa daisy × 5, yellow
- 8 Asiatic lily × 4, orange
- 9 Hardy gladiolus × 5, pink
- 10 Ornamental onion 'Purple Sensation' × 5, purple
Why this plant
- Part of the bed's structure. Shrubs and grasses keep their shape when the perennials die down. So does little bluestem.
Why here
- Anchors a back corner. At 4 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 wild quinine (3½ ft): no two neighbours there are the same height, so the back steps up and down like a skyline.
- One plant, alone. A shrub is seen as an object, and needs clear ground around it.
Why now
- In flower for three weeks. From late May to early June.
- Fills no gap. Every week it is in flower, at least three other kinds are too. It thickens a season that is already full.
Planned as an English border: 9 of the 9 groups (100%) are drifts, longer along the bed than they are deep. Pink is the colour seen most, on 3 of the 9 kinds grown for their flowers. The bed is balanced: the left half carries 52% of the visual weight and the right half 48%.
The planner's own design check: 11 Excellent, 5 Good, 1 Satisfactory.
Open this bed in the planner Change its size, the sun or the style, move plants about, or swap one for another.
Where snowmound spirea goes in a border
At 4 ft it belongs at the back of a bed. In the planner's ten height classes it is moderately tall (3 to 4 ft).
Its job: anchor. A shrub that gives the bed permanent structure. Planted singly, as soon as the front edge is laid; everything else is arranged around it.
A better-behaved, more compact bridal wreath for ordinary gardens. Prune it right after flowering, if at all.
- A white mound in late spring
- Informal hedges
- A tidier substitute for bridal wreath
What to plant with snowmound spirea
Plants recorded as good partners for it, and what each pairing does:
- Peony: in flower together for two weeks, from late May.
- Catmint 'Walker's Low': in flower together for three weeks, from late May; spires rising out of its mound; low enough (24 in) to stand in front of it.
- Siberian iris: in flower together for two weeks, from late May.
Questions about snowmound spirea
Does snowmound spirea need sun or shade?
Snowmound spirea grows in full sun (6 or more hours of direct sun a day).
It wants ordinary well-drained soil, of average fertility, and little watering once settled.
What zones does snowmound spirea 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 snowmound spirea flower in my zone?
In zone 5 it flowers late May to early June. 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 May to mid June |
|---|---|
| Zone 5 | Late May to early June |
| Zone 6 | Mid May to early June |
| Zone 7 | Early May to late May |
| Zone 8 | Early May to late 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 snowmound spirea be planted?
4 ft (120 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 5 ft (150 cm), so a group knits into one patch.
It grows 4 ft (120 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many snowmound spirea plants do I need?
Usually one. At 4 ft (120 cm) across, it is a plant you place, not one you mass. For a hedge or screen, set them 4 ft apart: three plants for a 10 ft run.
In the bed above, the planner used one in one group.
Is snowmound spirea 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 snowmound spirea?
Snowmound spirea is not native to North America. These North American natives come closest to doing its job:
- Ninebark 'Tiny Wine': the same job in a bed, the same flowering time and the same colour; 12 in narrower.
- Black chokeberry: the same job in a bed, the same flowering time and the same colour; 12 in taller, medium leaves, not fine.
- Arrowwood viburnum 'Blue Muffin': the same job in a bed, the same flowering time and the same colour; 24 in taller, medium leaves, not fine.
Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.
What flowers after snowmound spirea?
Snowmound spirea is over by early June. These start as it finishes and carry the same spot on, so it never goes flat:
- Bee balm: from early July to early August, 3 ft tall, to stand in front of it and cover its fading stems.
- Purple coneflower: from late June to early September, 3 ft tall, to stand in front of it and cover its fading stems.
- Daylily: from late June to early August, 2½ ft tall, to stand in front of it and cover its fading stems.
What does snowmound spirea look like in winter?
Snowmound spirea drops its leaves and stands as bare branches. That is when to see its shape, and to prune it if it needs pruning.
More Spiraea
- Birchleaf spirea 'Tor' Spiraea betulifolia 'Tor'
- Bridal wreath spirea Spiraea x vanhouttei
- Japanese spirea 'Goldflame' Spiraea japonica 'Goldflame'
- Japanese spirea 'Little Princess' Spiraea japonica 'Little Princess'
- Japanese spirea 'Magic Carpet' Spiraea japonica 'Magic Carpet'
- Spirea 'Grefsheim' Spiraea x cinerea 'Grefsheim'
- Spirea 'Ogon' Spiraea thunbergii 'Ogon'
- White meadowsweet Spiraea alba
In these guides
Every fact on record
- Type
- Shrub
- Size
- 4 ft (120 cm) tall, 5 ft (150 cm) wide
- Plant
- 4 ft (120 cm) apart
- Height class
- Moderately tall (3 to 4 ft)
- Place in the bed
- Back
- Flowers
- Late May to early June; dense clusters; white
- Leaves
- Fine texture, deciduous; dark green
- Shape
- Rounded, clumping
- Hardy in
- USDA zones 4 to 8
- Light
- Full sun
- Soil
- Average, well-drained
- Water
- Low
- Feeding
- None needed
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.