Lobelia laxiflora

RHS Plant Profile
Sierra Madre lobelia

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Sierra Madre lobelia RHS 1999
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Herbaceous Perennial
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An herbaceous, woody-based, rhizomatous perennial to 90cm tall, with arching stems bearing long, very narrow leaves and 4cm long tubular red and yellow flowers singly in the upper leaf axils in late spring and summer

Position

Full sun, Partial shade

Soil Types

Loam, Sand

Max Height

0.5-1 metres

Max Spread

1-1.5 metres

Size

Time to Maturity
2–5 years
Max Spread
1-1.5 metres
Max Height
0.5-1 metres

Growing Conditions

Loam Sand
Moisture
Moist but well–drained or Well–drained
pH
Alkaline or Neutral

Position

Full sun Partial shade
Aspect
South–facing or West–facing
Exposure
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)
H3

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Campanulaceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Bushy
Potentially harmful
Harmful if eatenskin irritant. Wear gloves and other protective equipment when handling Wear gloves and other protective equipment when handling. Pets: Harmful if eatenskin irritant. For further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants
Genus
Lobelia can be annuals, perennials or shrubs, with simple leaves and showy 2-lipped flowers that may be solitary or in racemes or panicles
Name Status
Correct
Plant Range
SW USA to Colombia

How to Grow

Cultivation

Of borderline hardiness - protect with a dry winter mulch or lift and store in a frost-free greenhouse. Prefers to be grown in deep, fertile, reliably moist soil in full sun or partial shade

Propagation

Propagate by semi-ripe cuttings

Suggested planting locations and garden types

  • City and courtyard gardens
  • Coastal
  • Cottage and informal garden
  • Flower borders and beds

Pruning

Cut back after flowering

Pests

May be susceptible to slugs

Diseases

May be susceptible to crown rot