How to Grow Starfruit
Averrhoa carambola
Starfruit is a compact tropical evergreen tree that needs a heated greenhouse in the UK with a minimum of 12C over winter. Give it full sun for best fruiting, keep soil consistently moist without waterlogging, and maintain good humidity by misting or using a humidity tray. Starfruit is a heavy feeder — apply a slow-release granular feed in spring and supplement with monthly liquid fertiliser, switching to high-potash when fruiting. It responds well to pruning and can be kept compact in a large container.
Yearly Lifecycle
Care Essentials
Feed monthly with a balanced liquid fertiliser throughout the year. Starfruit is a heavy feeder — apply a slow-release granular feed in spring and switch to high-potash when fruiting. Do not stop feeding entirely in winter as the tree may continue growing under supplementary lighting.
Watch For
- Glasshouse red spider mite — the most common pest; stippled leaves and fine webbing
- Scale insects on stems and older woody growth
- Mealybugs in leaf axils and on stems
- Anthracnose on fruit and leaves in humid poorly ventilated conditions
- Root rot from overwatering, especially in winter
Care Requirements
Light
Full sun; heated greenhouse in UK
Needs full sun for best fruiting. In the UK, grow in a heated greenhouse or large conservatory with maximum light. Tolerates partial shade but will fruit less.
Watering
Keep consistently moist; maintain good humidity
Water regularly to keep soil consistently moist. Starfruit does not tolerate drought or waterlogging. Maintain good humidity by misting or using a humidity tray.
Fertilizing
Monthly liquid feed; heavy feeder, extra potash for fruit
Feed monthly with a balanced liquid fertiliser during the growing season. Starfruit is a heavy feeder — apply a slow-release granular feed in spring and supplement with high-potash feed when fruiting.
Pruning
Prune late winter; responds well to size control
Prune in late winter to maintain shape and control size. Remove dead, crossing, or inward-growing branches. Responds well to pruning and can be kept compact in a large container.
Overwintering
Minimum 12°C; supplementary winter light helpful
Not frost hardy. Maintain a minimum of 12°C over winter. Keep in a heated greenhouse with supplementary lighting. Reduce watering slightly but maintain humidity.
Growing Tips
Feed generously
Starfruit is a heavy feeder — apply slow-release feed in spring and supplement with monthly liquid fertiliser.
Moist but not wet
Keep soil consistently moist and maintain good humidity; starfruit tolerates neither drought nor waterlogging.
Prune to control size
Prune in late winter to control size; starfruit responds well to pruning and can be kept compact in a large container.
Winter lighting helps
Provide supplementary lighting in winter to compensate for the UK's short days and maintain growth.
Pests & Diseases
Pest Glasshouse Red Spider Mite
Identification: Fine stippling on upper leaf surfaces. Leaves become dull and bronzed. Fine webbing visible in severe infestations.
- Introduce the predatory mite Phytoseiulus persimilis
- Mist foliage regularly to raise humidity
- Spray with insecticidal soap
- Spray with a miticide if biological control is insufficient
Pest Scale Insects
Identification: Small brown or white oval bumps on stems and leaf undersides. Sticky honeydew and sooty mould on foliage.
- Scrub off with a soft brush dipped in soapy water
- Apply a winter plant oil wash
- Encourage parasitic wasps
- Spray with a plant oil-based insecticide
Pest Mealybugs
Identification: White, waxy, cottony clusters in leaf axils and on stems. Sticky honeydew and sooty mould.
- Dab individual bugs with a cotton bud soaked in methylated spirit
- Introduce the ladybird Cryptolaemus montrouzieri as biological control
- Spray with insecticidal soap
- Spray with a systemic insecticide containing acetamiprid
Disease Anthracnose Colletotrichum gloeosporioides
Symptoms: Dark, sunken spots on fruit and leaves. Fruit may rot before ripening. Leaves develop brown patches and may drop.
Treatment: Remove and destroy affected fruit and leaves. Improve air circulation.
Prevention: Avoid overhead watering. Ensure good ventilation in the greenhouse. Remove fallen debris promptly.
Disease Root Rot Phytophthora spp.
Symptoms: Yellowing leaves, wilting despite moist soil, dark discolouration at the stem base. Roots are brown and mushy.
Treatment: Reduce watering. Repot into fresh, well-drained compost. Cut away affected roots.
Prevention: Use well-drained compost with added perlite. Avoid overwatering. Ensure containers have adequate drainage holes.
Spacing & Planting
| Plant spacing | 550 cm |
| Row spacing | 650 cm |
| Mature height | 600 cm |
| Mature spread | 400 cm |
Also called carambola. Compact evergreen tree. Multiple flowering flushes year-round. Fast fruit development (60-75 days).
