Carolina lupine
Thermopsis villosa · Fabaceae
Dense, upright spires of soft yellow, lupin-like flowers in late spring on a tall, bushy plant. It thrives where true lupines fail in heat and humidity.
- Size
- 4 ft tall, 2½ ft wide
- Zones
- 4 to 9
- Light
- Full sun
- Flowers
- Late May to late June
- Pets
- No toxicity recorded
- Job in a bed
- Accent
A bed built around Carolina lupine
The planner designed this bed around Carolina lupine 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 Carolina lupine stands where it does.
The plants
- 1 Carolina lupine × 3, yellow
- 2 Dianthus 'Kahori' × 3, pink
- 3 Sedum 'Lidakense' × 15, pink
- 4 Wild quinine × 5, white
- 5 Inkberry 'Gem Box' × 1, dark green leaves
- 6 Gray's sedge × 3, green
- 7 Spring starflower × 10, blue
- 8 Double snowdrop × 12, white
Why this plant
- The only spires. The others are open bowls, dense clusters, flat plates and others. Shape reads at a distance, where colours blur.
- The only yellow. The one hot colour: every other flower here is cool or neutral.
Why here
- Anchors a back corner. At 4 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 inkberry 'Gem Box' (2½ 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 five weeks. From late May to late June.
- Part of the bed's peak. With dianthus 'Kahori', wild quinine and Gray's sedge in late June: 4 kinds at once. No week has more.
Planned as a cottage garden: 23 of the 30 plants (77%), bulbs aside, stand alone or in groups of no more than five, small enough for the kinds to mingle. The longest in flower is dianthus 'Kahori': 17 weeks, from mid May to early September. Neither end outweighs the other: the visual weight is split 54 to 46, left to right.
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 Carolina lupine 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: accent. An upright plant used singly, like a punctuation mark, and repeated at intervals to give the bed rhythm.
The answer for gardeners who cannot grow lupines. It is long-lived, deep-rooted and drought-tolerant, and should be left undisturbed, like its relative false indigo.
- Yellow spires for hot-summer gardens
- The back of a sunny border
- Native planting
What to plant with Carolina lupine
Plants recorded as good partners for it, and what each pairing does:
- Bluestar: blue against yellow, opposite each other on the colour wheel, in flower together for four weeks; a low mound at the foot of its spires.
- Blue false indigo: blue against yellow, opposite each other on the colour wheel, in flower together for four weeks; a low mound at the foot of its spires.
- Peony: in flower together for four weeks, from late May; a low mound at the foot of its spires.
Questions about Carolina lupine
Does Carolina lupine need sun or shade?
Carolina lupine 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 Carolina lupine grow in?
USDA zones 4 to 9. It is hardy to zone 4, which means it survives winter nights down to about −20 °F (−29 °C).
Gardening in Canada? Use the USDA zone for your town: Canada's own zone map uses different numbers.
When does Carolina lupine flower in my zone?
In zone 5 it flowers late May to late 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 late June |
|---|---|
| Zone 5 | Late May to late June |
| Zone 6 | Mid May to late June |
| Zone 7 | Early May to mid June |
| Zone 8 | Early May to mid June |
| Zone 9 | Late April to early June |
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 Carolina lupine 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 4 ft (120 cm) tall. Give it the full distance from anything taller, or it will lean out towards the light.
How many Carolina lupine 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 Carolina lupine 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 Carolina lupine?
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 Carolina lupine?
Carolina lupine is over by late 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.
- Garden phlox: from mid July to early September, 3½ ft tall.
What does Carolina lupine look like in winter?
Carolina lupine 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.
In these guides
- Pet-safe plants for a sunny border
- Tall perennials and grasses for the back of a border
- Plants with spires: vertical accents
Zone guides: Zone 4 · Zone 5 · Zone 6 · Zone 7 · Zone 8 · Zone 9
Every fact on record
- Type
- Perennial
- Size
- 4 ft (120 cm) tall, 2½ ft (75 cm) wide
- Plant
- 24 in (60 cm) apart
- Height class
- Moderately tall (3 to 4 ft)
- Place in the bed
- Back
- Flowers
- Late May to late June; upright spires; yellow
- Leaves
- Medium texture, herbaceous; green
- Shape
- Upright, clumping
- Hardy in
- USDA zones 4 to 9
- Light
- Full sun
- Soil
- Average, well-drained
- Water
- Low
- Feeding
- None needed
- Family
- Fabaceae
- Comes from
- Southeastern United States
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.