Oncidium Pumistor gx

RHS Plant Profile
dancing lady orchid Pumistor gx

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Synonyms

Odontoglossum Pumistor gx
Odontoglossum (_crispum_ × Cristor gx)

Conservatory Greenhouse Houseplants

A medium-sized, epiphytic orchid with upright, 20-40cm long, evergreen leaves. New growth appears from the base of swollen stems (pseudobulbs). Each pseudobulb serves as a storage organ for water and nutrients. They are oval-shaped, slightly flattened, carrying two or more leaves from the tip. The plant typically flowers in autumn or spring, on 30-50cm long, uprigh, arching stems. New flowering stems arise from the axils of young mature pseudobulbs, wrapped partially with leafed sheaths. The flowers are star-shaped, pale white, occasionally with reddish spots and have a yellow centre. Each flower measures 5-10cm across.

Position

Partial shade

Max Height

0.5-1 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity
5–10 years
Max Spread
0.1-0.5 metres
Max Height
0.5-1 metres

Growing Conditions

Moisture
Moist but well–drained or Well–drained
pH
Neutral

Position

Partial shade
Aspect
East–facing or North–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)
H1B

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Orchidaceae
Native to GB/Ireland
No
Foliage
Evergreen
Habit
Columnar upright, Clump forming
Potentially harmful
Skin allergen. Wear gloves and other protective equipment when handling
Genus
Oncidium are a large genus of epiphytic orchids; mature plants form clumps of ovoid to conical pseudobulbs, each with 1-3 mid-green, variably-shaped, leathery leaves arising from the tips. Flower panicles from the bases of the pseudobulbs widely differ in colour and shape
Name Status
Accepted

How to Grow

Cultivation

Grow in an open bark-based orchid compost with addition of perlite, sphagnum moss or coir. Provide enough bright filtered light, but keep away from direct sunlight or a heating source. Ideal temperatures are around minimum 8°C at night and up to maximum 25 °C during day. Water regularly, when the pot feels light when lifted. Ensure that all water drains away, preventing the plant sitting wet. Orchid fertiliser can be applied regularly throughout the growing season. Reduce watering and feeding in winter months. For more notes on cultivation, see oncidium orchid (cool) cultivation

Propagation

Propagation by seed is only possible in a controlled laboratory environment. Mature plants may be divided when the plant overgrows its container. Each division should have at least 3 older pseudobulbs with a sufficient amount of stored energy and water, to support new growth and reduce stress after repotting.

Suggested planting locations and garden types

  • Houseplants
  • Conservatory and greenhouse

Pruning

No pruning required. Cut off spent flower spikes.

Pests

May be susceptible to mealybugs, aphids and scale insects.

Diseases

Generally disease-free. Poor air movement may cause bacterial or fungal rots. Good hygiene practice and sterilising cutting tools prevent the spread of virus diseases.