Tuberous Jerusalem sage
Phlomis tuberosa · Lamiaceae
Tall, dark red stems with whorls of lilac-pink, hooded flowers at intervals up their length, over large, arrow-shaped leaves.
- Size
- 5 ft tall, 2½ ft wide
- Zones
- 3 to 8
- Light
- Full sun
- Flowers
- Mid June to late July
- Pets
- Not checked
- Job in a bed
- Accent
A bed built around tuberous Jerusalem sage
The planner designed this bed around tuberous Jerusalem 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 tuberous Jerusalem sage stands where it does.
The plants
- 1 Tuberous Jerusalem sage × 3, pink
- 2 Sea thrift × 8, white
- 3 Winter heath × 5, purple
- 4 Gloriosa daisy 'Indian Summer' × 5, yellow
- 5 Silver sage × 1, silver leaves
- 6 Italian bugloss 'Dropmore' × 5, blue
- 7 Ornamental onion 'Purple Sensation' × 5, purple
- 8 Tulip 'Ballerina' × 7, orange
Why this plant
- The only spires. The others are globes, bells, daisies and others. Shape reads at a distance, where colours blur.
- The only pink.
Why here
- Anchors a back corner. At 5 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 gloriosa daisy 'Indian Summer' (3 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 7 weeks. From mid June to late July.
- Part of the bed's peak. With sea thrift and Italian bugloss 'Dropmore' in mid June: 3 kinds at once. No week has more.
Planned as a cottage garden: 27 of the 27 plants (100%), bulbs aside, stand alone or in groups of no more than five, small enough for the kinds to mingle. Neither end outweighs the other: the visual weight is split 49 to 51, left to right. Cool colours (pink, purple and blue) with yellow and orange as the warm notes, and white to calm things between them.
The planner's own design check: 10 Excellent, 6 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 tuberous Jerusalem sage goes in a border
At 5 ft it belongs at the back of a bed. In the planner's ten height classes it is tall (4 to 5 ft).
Its job: accent. An upright plant used singly, like a punctuation mark, and repeated at intervals to give the bed rhythm.
A plant of the steppe, and a pillar of naturalistic planting: the tiered seed heads stand all winter. Hardy to zone 3 and untroubled by drought.
- Winter seed heads
- Naturalistic planting with grasses
- Tall accents for dry soil
What to plant with tuberous Jerusalem sage
Plants recorded as good partners for it, and what each pairing does:
- Feather reed grass 'Karl Foerster': in flower together for six weeks, from late June; fine leaves against its bold ones.
- Purple coneflower: in flower together for five weeks, from late June; medium leaves against its bold ones; low enough (3 ft) to stand in front of it.
- Russian sage: in flower together for three weeks, from mid July; fine leaves against its bold ones.
Questions about tuberous Jerusalem sage
Does tuberous Jerusalem sage need sun or shade?
Tuberous Jerusalem sage 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 tuberous Jerusalem sage 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 tuberous Jerusalem sage flower in my zone?
In zone 5 it flowers mid June to late July. As a summer flower it moves about half a week for every zone: earlier where it is warmer.
| Zone 3 | Late June to early August |
|---|---|
| Zone 4 | Late June to early August |
| Zone 5 | Mid June to late July |
| Zone 6 | Mid June to late July |
| Zone 7 | Early June to mid July |
| Zone 8 | Early June to mid July |
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 tuberous Jerusalem 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 2½ ft (75 cm), so a group knits into one patch.
It grows 5 ft (150 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many tuberous Jerusalem 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, repeated along the bed at intervals; a slender one reads better as a clump of three.
In the bed above, the planner used three in one group.
Is there a native plant like tuberous Jerusalem sage?
Tuberous Jerusalem sage is not native to North America. These North American natives come closest to doing its job:
- Giant coneflower: the same job in a bed and the same flowering time; 12 in taller, yellow, not pink.
- Culver's root: the same job in a bed and the same size; flowers early July to mid August, white or lavender, not pink.
- Lupine: the same job in a bed and the same colour; 20 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.
What flowers after tuberous Jerusalem sage?
Tuberous Jerusalem sage is over by late July. These start as it finishes and carry the same spot on, so it never goes flat:
- Tiger lily: from late July to late August, 4 ft tall.
- Garden phlox: from mid July to early September, 3½ ft tall, to stand in front of it and cover its fading stems.
- Hardy hibiscus: from late July to mid September, 5 ft tall.
What does tuberous Jerusalem sage look like in winter?
Tuberous Jerusalem sage dies down, but leave the stems standing: the seed heads stand through the winter. Cut them down in early spring, before the new shoots come.
More Phlomis
- Jerusalem sage Phlomis russeliana
In these guides
Zone guides: Zone 3 · Zone 4 · Zone 5 · Zone 6 · Zone 7 · Zone 8
Every fact on record
- Type
- Perennial
- Size
- 5 ft (150 cm) tall, 2½ ft (75 cm) wide
- Plant
- 24 in (60 cm) apart
- Height class
- Tall (4 to 5 ft)
- Place in the bed
- Back
- Flowers
- Mid June to late July; upright spires; pink, lavender
- Leaves
- Bold texture, herbaceous; dark green
- Shape
- Upright, clumping
- Hardy in
- USDA zones 3 to 8
- Light
- Full sun
- Soil
- Average, well-drained
- Water
- Low
- Feeding
- None needed
- Family
- Lamiaceae
Not yet checked against an outside reference: its figures rest on general horticultural knowledge. 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.