Bog sage
Salvia uliginosa · Lamiaceae
Small flowers of clear sky blue and white, at the tips of tall, thin, swaying stems, from late summer until frost.
- Size
- 5½ ft tall, 3 ft wide
- Zones
- 6 to 10
- Light
- Full sun
- Flowers
- Late July to mid October
- Pets
- No toxicity recorded
- Job in a bed
- Weaver
A bed built around bog sage
The planner designed this bed around bog sage when this page was made: a 12 × 6 ft (3.7 × 1.8 m) cottage garden in zone 6, full sun. It chose the other plants from the 966 that suit those conditions, and says below why bog sage stands where it does.
The plants
- 1 Bog sage × 3, blue
- 2 Winter heath × 8, pink
- 3 Coral bells 'Firefly' × 5, red
- 4 Silver sage × 1, silver leaves
- 5 Tatarian aster 'Jindai' × 4, purple
- 6 Camassia × 5, blue
- 7 Spring starflower × 12, blue
Why this plant
- Nothing here is unique to it. Its leaf, flower shape and colour are all on the plan already. Its case rests on where it stands and when it performs.
Why here
- Anchors a back corner. At 5½ ft it is the tallest plant 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 Tatarian aster 'Jindai' (4 ft): no two neighbours there are the same height, so the back steps up and down like a skyline.
- 3 plants in one clump. A single spire is too slight to hold a place alone, so here the accent is a clump.
Why now
- In flower for 13 weeks. From late July to mid October.
- Fills a gap. For 9 of those weeks nothing else on the plan is in flower.
Planned as a cottage garden: 21 of the 21 plants (100%), bulbs aside, stand alone or in groups of no more than five, small enough for the kinds to mingle. Winter heath is planted in three places along the bed, which gives it rhythm. The scheme leans cool (blue, pink and purple) and uses red for warmth.
The planner's own design check: 11 Excellent, 5 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 bog sage goes in a border
At 5½ ft it belongs at the back of a bed. In the planner's ten height classes it is very tall (5 to 6½ ft). It is airy enough to see through, so it can also come forward and veil what is behind it.
Its job: weaver. A light, airy plant threaded singly between sturdier ones to knit the planting together.
A see-through plant, tall and almost weightless, for threading through the back of a border. Unusually for a salvia it likes moist soil, where it runs.
- Sky blue for late summer
- An airy screen
- Moist borders
What to plant with bog sage
Plants recorded as good partners for it, and what each pairing does:
- Joe Pye weed 'Gateway': in flower together for eight weeks, from late July; bold leaves against its medium ones; happy in the same moist soil.
- Switchgrass 'Northwind': in flower together for nine weeks, from early August.
- New England aster: in flower together for six weeks, from early September; happy in the same moist soil.
Questions about bog sage
Does bog sage need sun or shade?
Bog sage grows in full sun (6 or more hours of direct sun a day).
It wants soil that stays evenly moist, of average fertility, and a good soak in dry spells. It copes with soil that stays wet.
What zones does bog sage grow in?
USDA zones 6 to 10. It is hardy to zone 6, which means it survives winter nights down to about 0 °F (−18 °C).
Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.
When does bog sage flower in my zone?
In zone 5 it flowers late July to mid October. As a summer flower it moves about half a week for every zone: earlier where it is warmer.
| Zone 6 | Late July to mid October |
|---|---|
| Zone 7 | Mid July to mid October |
| Zone 8 | Mid July to mid October |
| Zone 9 | Mid July 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 bog sage be planted?
24 in (60 cm) apart, from the middle of one plant to the middle of the next. That is a little closer than its full width of 3 ft (90 cm), so a group knits into one patch.
It grows 5½ ft (170 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many bog sage plants do I need?
At 24 in apart, set out in staggered rows:
- 3 to fill 10 square feet (about 1 m²)
- 6 for a single row 10 ft (3 m) long
- 10 to fill a 4 × 8 ft bed on its own
In a mixed border, plant it as one at a time, threaded between sturdier plants.
In the bed above, the planner used three in one group.
Is bog sage 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 bog sage?
Bog sage comes from Southeastern & Southern Brazil to Northern Argentina. These North American natives come closest to doing its job:
- Grey-headed coneflower: the same job in a bed; 20 in shorter, 8 in narrower.
- Blue sage: the same job in a bed and the same colour; 20 in shorter, 6 in narrower.
- Garden phlox 'Jeana': a drift, not a weaver, 20 in shorter.
Matched the way the planner's Swap button matches plants: the same job in a bed, then size, then flowering time.
Do deer eat bog sage?
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 bog sage spread?
It spreads sideways, by runners or roots; the risk of it taking over is moderate. Spreads by underground runners in moist soil. Dig out stray shoots in spring.
What flowers after bog sage?
Bog sage is over by mid October. These start as it finishes and carry the same spot on, so it never goes flat:
- Bodnant viburnum 'Dawn': from early November to late December, 10 ft tall.
- Common witch hazel: from mid October to late November, 15 ft tall.
What does bog sage look like in winter?
Bog sage 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 bog sage good for bees and butterflies?
Bog sage is visited by bees, butterflies and hummingbirds.
More Salvia
- Anise sage 'Black and Blue' Salvia guaranitica 'Black and Blue'
- Autumn sage Salvia greggii
- Blue sage Salvia azurea
- Clary sage Salvia sclarea
- Culinary sage Salvia officinalis
- Meadow sage Salvia nemorosa
- Meadow sage 'Caradonna' Salvia nemorosa 'Caradonna'
- Mexican bush sage Salvia leucantha
- Rosemary Salvia rosmarinus
- Russian sage Salvia yangii (formerly Perovskia)
- Russian sage 'Little Spire' Salvia yangii 'Little Spire'
- Salvia 'Hot Lips' Salvia microphylla 'Hot Lips'
- Salvia 'May Night' Salvia nemorosa 'Mainacht'
- Silver sage Salvia argentea
- Whorled sage 'Purple Rain' Salvia verticillata 'Purple Rain'
- Wood sage 'Blue Hill' Salvia x sylvestris 'Blauhügel'
- Wood sage 'East Friesland' Salvia nemorosa 'Ostfriesland'
In these guides
- Plants for wet soil and rain gardens
- Deer-resistant perennials for full sun
- Pet-safe plants for a sunny border
- Plants for hummingbirds
- Plants for butterflies
- Plants for bees
- Tall perennials and grasses for the back of a border
- Plants with spires: vertical accents
- Long-flowering plants: 12 weeks or more
- Plants with blue flowers
Every fact on record
- Type
- Perennial
- Size
- 5½ ft (170 cm) tall, 3 ft (90 cm) wide
- Plant
- 24 in (60 cm) apart
- Height class
- Very tall (5 to 6½ ft)
- Place in the bed
- Back, or further forward: it is airy enough to see through
- Flowers
- Late July to mid October; upright spires; blue
- Leaves
- Medium texture, herbaceous; green
- Shape
- Upright, spreading
- Hardy in
- USDA zones 6 to 10
- Light
- Full sun
- Soil
- Average, evenly moist
- Water
- Moderate
- Feeding
- None needed
- Family
- Lamiaceae
- Comes from
- Southeastern & Southern Brazil to Northern Argentina
- Attracts
- Bees, butterflies, hummingbirds
- Stands up to
- Deer, wet soil, poor soil
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.