Woodland phlox 'Blue Moon'
Phlox divaricata 'Blue Moon' · Polemoniaceae
Full, overlapping petals of deep violet-blue, the richest colour in the species, in scented clusters over creeping stems.
- Size
- 12 in tall, 18 in wide
- Zones
- 3 to 8
- Light
- Part shade to shade
- Flowers
- Late April to late May
- Pets
- No toxicity recorded
- Job in a bed
- Drift
A bed built around woodland phlox 'Blue Moon'
The planner designed this bed around woodland phlox 'Blue Moon' 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 woodland phlox 'Blue Moon' stands where it does.
The plants
- 1 Woodland phlox 'Blue Moon' × 4, blue
- 2 Moor grass 'Greenlee' × 5, tan
- 3 Blue wood aster × 3, lavender
- 4 Tall astilbe 'Superba' × 4, purple
- 5 Dwarf English boxwood × 1, dark green leaves
- 6 Hellebore 'Pink Frost' × 3, pink
- 7 Double snowdrop × 12, white
- 8 Hardy cyclamen × 12, pink
Why this plant
- The only dense clusters. The others are spires, daisies, plumes and others. Shape reads at a distance, where colours blur.
- The only blue.
Why here
- On the front edge. At 12 in it frames the bed without hiding it, and it is in leaf all season. It finishes 40% of the edge.
- 4 plants in 2 runs (3 and 1). Runs of different lengths make the edge a frame, not a ruled line.
Why now
- In flower for six weeks. From late April to late May.
- Fills a gap. For three of those 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. Blue, lavender, purple, pink, tan and white make a cool, restful scheme. Tall astilbe 'Superba' and blue wood aster anchor the back corners of the bed: the tallest plants on the plan stand there.
The planner's own design check: 14 Excellent, 3 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 woodland phlox 'Blue Moon' goes in a border
At 12 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.
Selected at the New England Wild Flower Society. It carpets the ground under deciduous trees in May, with a scent that drifts, then retires quietly.
- Blue carpet in spring shade
- Scent in the woodland garden
- Planting with tulips and ferns
What to plant with woodland phlox 'Blue Moon'
Plants recorded as good partners for it, and what each pairing does:
- Foamflower: in flower together for six weeks, from late April; spires rising out of its mound; happy in the same moist soil.
- White trillium: in flower together for four weeks, from late April; happy in the same moist soil.
- Christmas fern: its dark green leaves are a setting for the flowers, before and after; tall enough (20 in) to stand behind it.
Questions about woodland phlox 'Blue Moon'
Does woodland phlox 'Blue Moon' need sun or shade?
Woodland phlox 'Blue Moon' 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. Once settled in, it stands drought.
What zones does woodland phlox 'Blue Moon' grow in?
USDA zones 3 to 8. It is hardy to zone 3, which means it survives winter nights down to about −30 °F (−34 °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 woodland phlox 'Blue Moon' flower in my zone?
In zone 5 it flowers late April 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 3 | Early May to mid June |
|---|---|
| Zone 4 | Early May to early June |
| Zone 5 | Late April to late May |
| Zone 6 | Mid April to late May |
| Zone 7 | Mid April to mid May |
| Zone 8 | 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 woodland phlox 'Blue Moon' be planted?
14 in (35 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 18 in (45 cm), so a group knits into one patch.
It grows 12 in (30 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many woodland phlox 'Blue Moon' plants do I need?
At 14 in apart, set out in staggered rows:
- 9 to fill 10 square feet (about 1 m²)
- 9 for a single row 10 ft (3 m) long
- 28 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 four in two groups.
Is woodland phlox 'Blue Moon' 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.
Do deer eat woodland phlox 'Blue Moon'?
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 woodland phlox 'Blue Moon'?
Woodland phlox 'Blue Moon' 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 woodland phlox 'Blue Moon' look like in winter?
Woodland phlox 'Blue Moon' holds some of its leaves into winter, more in a mild year or a sheltered spot, and they look tired by March. Cut the old ones off as new growth starts.
Is woodland phlox 'Blue Moon' good for bees and butterflies?
Woodland phlox 'Blue Moon' is visited by bees, butterflies and hummingbirds.
It is native to the United States and Canada (this is a named variety of the native plant).
More Phlox
- Creeping phlox Phlox subulata
- Creeping phlox 'Candy Stripe' Phlox subulata 'Candy Stripe'
- Creeping phlox 'Emerald Blue' Phlox subulata 'Emerald Blue'
- Creeping phlox 'Sherwood Purple' Phlox stolonifera 'Sherwood Purple'
- Creeping woodland phlox Phlox stolonifera
- Garden phlox Phlox paniculata
- Garden phlox 'Bright Eyes' Phlox paniculata 'Bright Eyes'
- Garden phlox 'David' Phlox paniculata 'David'
- Garden phlox 'Jeana' Phlox paniculata 'Jeana'
- Garden phlox 'Laura' Phlox paniculata 'Laura'
- Woodland phlox Phlox divaricata
In these guides
- Plants for dry shade
- Pet-safe plants for shade
- Native perennials for pollinators
- Native plants for shade
- Garden plants native to Canada
- Plants for hummingbirds
- Plants for butterflies
- Plants for bees
- Low plants for the front of a border
- Plants with blue flowers
Zone guides: Zone 3 · Zone 4 · Zone 5 · Zone 6 · Zone 7 · Zone 8
Every fact on record
- Type
- Perennial
- Size
- 12 in (30 cm) tall, 18 in (45 cm) wide
- Plant
- 14 in (35 cm) apart
- Height class
- Low (6 to 12 in)
- Place in the bed
- Front
- Flowers
- Late April to late May; dense clusters; blue, lavender
- Leaves
- Medium texture, semi-evergreen; green
- Shape
- Mounding, spreading
- Hardy in
- USDA zones 3 to 8
- Light
- Part shade, shade
- Soil
- Rich, evenly moist
- Water
- Moderate
- Feeding
- None needed
- Family
- Polemoniaceae
- Comes from
- Eastern North America
- Attracts
- Bees, butterflies, hummingbirds
- Stands up to
- Drought
Checked against NC State Extension and VASCAN (plants of Canada). 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.