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Herbaceous Perennial

Thermopsis montana

false lupin

A suckering herbaceous perennial, up to 90cm high, with silky, silvery blue-green leaves with three oval leaflets, and spikes of yellow broom-like flowers in early summer and sometimes again in early autumn

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Ultimate height

0.5–1 metres

Time to ultimate height

2–5 years

Ultimate spread

0.5–1 metres

Chalk

Loam

Sand

Moisture

Moist but well–drained

pH

Acid, Alkaline, Neutral

	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Full sun
Partial shade

Aspect

South–facing or West–facing or East–facing

Exposure

Exposed or Sheltered

Hardiness
Hardiness ratings
All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets
H1a: under glass all year (>15C)
H1b: can be grown outside in the summer (10 - 15)
H1c: can be grown outside in the summer (5 - 10)
H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
H4: hardy through most of the UK (-10 to -5)
H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
H6: hardy in all of UK and northern Europe (-20 to -15)
H7: hardy in the severest European continental climates (< -20)

Botanical details

Family: Fabaceae
Native to GB / Ireland: No
Foliage: Deciduous
Habit: Suckering
Potentially harmful: Harmful if eaten. Wear gloves and other protective equipment when handling Pets (dogs): Harmful if eaten - for further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants
Genus: Thermopsis are lupin-like rhizomatous herbaceous perennials with erect stems, leaves with three leaflets, and yellow or purple flowers
Name status: Correct
Plant range: NW USA

How to grow

Cultivation

Grow in well-drained soil in sun or partial shade; cut down faded flower spikes to just above ground level; dig out roots if the plant spreads into unwanted areas

Propagation

Propagate by seed or division in spring

Suggested planting locations and garden types

Cottage and informal garden
Prairie planting
Banks and slopes

Pruning

No pruning required, but if the faded flower spikes are cut down to just above ground level there may be a second flush of flowering in early autumn

Pests

Generally pest-free

Diseases

Generally disease-free

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