Star Fruit Farming Profit Per Acre (Carambola)

Star Fruit Farming

Star fruit, or Carambola, is mainly eaten fresh but is also used for juice, preserves, jams, and jellies. Less commonly, it features in tea infusions, wine, and brandy. Traditionally valued for potential health benefits like lowering blood pressure, it’s also used in herbal remedies. Flowering trees support beekeeping by providing nectar and pollen for quality honey production.

Star fruit farming profit per acre offers promising long-term returns, making it a highly viable horticultural venture. The break-even point is typically reached by the 5th year, when cumulative cash flow turns positive and the initial investment is recovered.

Peak profitability occurs during the 8th to 10th year, with annual net profits reaching up to NRs. 532,400. From the 11th to 20th year, farmers can expect steady returns ranging between NRs. 398,000 and NRs. 230,000 per year.

Even beyond 20 years, during the low maintenance phase, the orchard remains profitable with an average yearly return of around NRs. 62,000. Overall, star fruit farming can generate cumulative profits exceeding NRs. 5 million per acre over a 20-year period, underscoring its long-term economic potential.

Land Preparation

Land preparation for star fruit cultivation involves several key steps to ensure optimal soil conditions. Begin with 1–2 deep plowings (30–45 cm) to break hardpans and enhance soil aeration and drainage, accommodating the star fruit’s shallow yet wide root system.

Follow this with 2–3 cross harrowings to break soil clods, mix in organic matter, and achieve a fine, level tilth suitable for precise planting. Mark planting spots based on the selected spacing pattern (square, rectangular, or hexagonal) using pegs for accuracy. During the final stage of land preparation, apply 15–20 tons per acre of well-decomposed farmyard manure or compost uniformly as basal manure to enrich soil fertility.

Soil Type

For optimal growth, star fruit requires deep, fertile, well-drained loamy soils with high organic content. Ensuring good drainage is essential because these plants are highly prone to Phytophthora root rot in saturated conditions. Heavy clay soils are typically inadequate unless substantially improved.

The ideal soil pH is slightly acidic to neutral, between 5.5 and 6.5. While the crop can tolerate pH levels up to 7.5, this requires diligent management of micronutrients like iron and zinc. Star fruit also shows moderate tolerance to salinity, but excessive salt will markedly hinder both its development and fruit production.

Climatic Requirements

Star fruit grows best in tropical to subtropical regions, ideally within a temperature range of 25°C to 35°C. Its growth slows below 15°C, with young trees being especially prone to frost damage, while mature ones may withstand light, short-term frosts with minor canopy loss.

The crop flourishes in moderate to high humidity levels (60–80%) and needs evenly distributed rainfall between 1500 and 2500 mm annually for optimal development. Once established, it can handle brief dry periods, but regular irrigation is vital to sustain fruit quality and yield, as extended droughts can result in flower and fruit drop.

Full sunlight exposure of 6–8 hours per day is crucial for strong flowering, fruiting, and flavor. Because young trees are sensitive to wind, protective windbreaks should be used in exposed locations to minimize fruit blemishing and branch breakage.

Major Cultivars

Seedling Rate per Acre

Use high-quality budded or grafted plants sourced from certified nurseries. Approximately 112 seedlings are required per acre for optimal spacing and growth.

Planting

Planting Season

In tropical regions, the best time to plant star fruit is during the start of the rainy season (June–September) to guarantee enough moisture for seedling establishment; in subtropical regions with irrigation, planting should take place in the early spring (March–April).

Spacing
For standard star fruit trees, the most common planting method is the square system, with a spacing of 6 meters by 6 meters to allow adequate room for growth and maintenance.

Pit Preparation
Pits should be dug at marked spots 3–4 weeks before planting, each measuring 60 cm x 60 cm x 60 cm. Separate the topsoil from the subsoil, and fill the pit with a well-mixed combination of topsoil, 10–15 kg of well-decomposed farmyard manure or compost, 500 g of bone meal or Single Super Phosphate (SSP), 500 g of neem cake (optional, for pest control), and 200–300 g of Muriate of Potash (MOP). The mixture should be slightly mounded above ground level, thoroughly watered, and left to settle before planting.

Planting Method
Carefully extract the sapling from its container to avoid root damage. Place it centrally in the hole, ensuring the graft union remains 10–15 cm (4–6 inches) above ground. Backfill with soil, firm gently around roots, and water deeply. Stake trees in windy locations. Apply organic mulch (e.g., straw/wood chips) around the base—kept away from the trunk—to conserve moisture and control weeds.

Number of Plants per Acre
The number of plants that can be accommodated is approximately 112 trees per acre.

Intercropping

Intercropping is feasible in young orchards during the first 2–4 years before canopy closure and is best suited for shallow-rooted, low-growing, non-competitive crops such as vegetables like bush beans, lettuce, radishes, leafy greens, ginger, and turmeric, as well as legumes like cowpea and black gram (urd) for green manure or grain, with pineapple being a common compatible intercrop. This practice provides benefits including early income generation, weed control, and soil health improvement, particularly through the inclusion of legumes.

Irrigation

The critical periods for irrigation in star fruit cultivation are the establishment phase in the first year, flowering, fruit set, fruit development, and during prolonged dry spells, all of which require adequate moisture to ensure healthy growth and yield. Irrigation schedule for star fruit is provided in the table below:

Pruning

Proper pruning is crucial for carambola plants to maintain a manageable shape, support healthy growth, and ensure high yields. It involves removing diseased branches and water shoots to improve air circulation, reduce the risk of disease, and make fruit bagging easier.

Keeping the tree height between 2 to 4 meters facilitates effective foliar spraying and stimulates flowering. Pruning is usually stopped once the tree starts fruiting, and common training systems include the open center, modified central leader, and trellis branching methods.

Young starfruit trees should be pruned during their first 1–2 years by trimming branches exceeding 60–90 cm (2–3 ft) to promote lateral branching. Depending on preference, trees can be shaped into a modified central leader or open center structure.

Mature trees require regular pruning to maintain a height of 1.8–3.6 meters (6–12 ft), including selective removal of upper limbs to avoid shading the lower canopy. This practice supports overall tree health, boosts fruit production, simplifies spraying and harvesting, and helps minimize storm damage. It is important not to remove the lower branches.

Fertilizer and Manure

Always follow the soil test report for accurate fertilizer application; however, the following is a general recommendation for fertilizer use in star fruit cultivation.

Weed Control

Weed control in star fruit orchards is most critical during the first 3–4 years, before the tree canopy develops enough to naturally suppress weeds. The most effective method is mulching, using a thick layer (8–15 cm) of organic material within the tree’s drip line while keeping it away from the trunk.

This helps suppress weed growth, conserve moisture, regulate soil temperature, and improve organic matter. Mechanical cultivation, such as shallow hoeing between rows and careful hand weeding around trees, can also be practiced to avoid damaging surface roots.

Chemical control should be used cautiously, applying only pre-emergent herbicides like Diuron (600g/acre) or Oxyfluorfen (400g/acre) under the canopy while strictly avoiding contact with the tree bark. Persistent weeds may be spot-treated with glyphosate (500g/acre), ensuring the tree trunk is well protected. Plastic mulch is generally less preferred than organic mulch in star fruit orchards.

Flowering and Fruit Management:

Flowering
In tropical places, star fruit trees bloom in several flushes throughout the year, with the spring and summer seeing the most blossom. On new branches and sometimes on aged wood or the trunk (cauliflory), the minuscule, pink-lavender blossoms bloom in panicles. Pollinators such as bees are drawn to these blossoms.

Pollination
Although star fruit is generally self-fertile, insect pollination—especially by bees—significantly improves fruit set and size. Therefore, maintaining habitats for pollinators is beneficial for optimal yield.

Fruit Set and Thinning
Star fruit trees tend to set a large number of fruits, which can result in smaller-sized produce and even limb breakage. A natural fruit drop occurs about 2–4 weeks after fruit set. After this period, hand thinning is recommended to remove misshapen, damaged, or overly clustered fruits. Ideally, fruits should be spaced 10–15 cm apart on branches to enhance size, quality, and reduce stress on limbs.

Pruning
For young trees, training should focus on developing 3–5 well-spaced scaffold limbs while removing low branches (below 60–90 cm) and inward- or crossing branches. Mature trees should be pruned either after the main harvest or just before the major flowering flush.

Pruning objectives include removing dead, diseased, or damaged (DDD) wood, thinning crowded branches to improve airflow and light, removing water sprouts and excessive upright growth, shortening long branches to prevent breakage, and maintaining an open canopy without heavy topping.

Fruit Support
Support is generally unnecessary unless branches become heavily laden, in which case they may be propped with forked sticks to prevent breakage.

Pest and Disease Management

Common Pests

Fruit Flies 

Fruit flies (Bactrocera spp.) pose a significant threat to star fruit cultivation, as their larvae tunnel into the fruit, causing severe damage and making it unmarketable.

Effective control involves an integrated approach, starting with regular field sanitation by collecting and destroying fallen and infested fruits to break the pest life cycle. Bait sprays using Spinosad at 0.5 ml/liter of water or Malathion (1.0–1.5 ml/liter) combined with protein hydrolysate as an attractant can be applied to target adult flies.

Male Annihilation Technique (MAT) traps containing methyl eugenol mixed with a small amount of Malathion can also be deployed at 8-10 traps per acre to attract and kill male flies. Additional measures such as bagging individual fruits shortly after fruit set and harvesting fruits at the right maturity stage help minimize infestation.

Scale Insects & Mealybugs

Scale insects and mealybugs weaken star fruit plants by sucking sap and excreting honeydew, which promotes sooty mold and reduces fruit quality. Control measures include 2% dormant oil sprays during the non-flowering stage, 1–2% insecticidal soap for light infestations, and Imidacloprid at 0.3–0.5 ml/liter for severe cases. Natural predators like lady beetles and parasitoid wasps also aid in pest control.

Mites (Spider Mites, Rust Mites)

Mites, including spider mites and rust mites, cause damage to star fruit plants by feeding on leaves and fruits, leading to leaf stippling, bronzing, and russeting of the fruit surface.

Effective management includes applying miticides such as Abamectin at 0.5 ml per liter or Fenpyroximate at 0.5–1 ml per liter of water, targeting the undersides of leaves where mites often reside. Regular water sprays can help dislodge mites in light infestations, and conserving natural predators like predatory mites and lady beetles supports long-term biological control.

Stem Borers

Stem borers are destructive pests whose larvae tunnel into the branches and trunks of star fruit trees, weakening the structure and potentially killing affected limbs. Control involves inserting a thin wire into active borer holes to kill the larvae, followed by injecting a contact insecticide such as Dichlorvos at 1–2 ml per liter directly into the holes. After treatment, the holes should be sealed with mud or wax to prevent re-infestation. Severely infested branches should be pruned and destroyed to limit the spread of the pest.

Birds & Bats

Birds and bats often damage ripe star fruit by feeding on them, leading to significant crop losses. The most effective control method is the use of protective netting over the trees or orchard area. Additional measures such as scare devices (e.g., reflective tape, sound makers, or decoy predators) can provide supplementary protection, though they are generally less reliable than netting.

Common Diseases

Phytophthora Root Rot & Collar Rot

Phytophthora root rot and collar rot are among the most serious diseases affecting star fruit, particularly in poorly drained or waterlogged soils, leading to symptoms such as wilting, dieback, and eventual tree death. Effective management begins with improving drainage and avoiding water stagnation around the root zone.

Fungicide drenches can be applied using Fosetyl-Al at 2–2.5 g per liter, Metalaxyl at 1–2 ml per liter, or phosphonate-based products as per label instructions, applied around the root zone at regular intervals during high-risk periods. Use of resistant rootstocks, if available, can also enhance long-term disease resistance.

Anthracnose

Anthracnose causes dark, sunken lesions on star fruit leaves, twigs, and fruit, particularly during wet weather, leading to reduced fruit quality and yield.

Effective control includes regular fungicide sprays such as copper-based formulations at 2–3 g per liter, Azoxystrobin at 0.1–0.2 g per liter, or Thiophanate-methyl at 1–2 g per liter, applied every 10–14 days during the rainy season. Good orchard sanitation by removing and destroying infected plant parts, along with maintaining proper spacing and pruning for good air circulation, helps reduce disease pressure.

Algal Spot

Algal spot on star fruit appears as rusty-orange, raised spots on leaves and stems and is typically a cosmetic issue with minimal impact on plant health. In severe cases, control can be achieved by applying copper-based fungicides at 2–3 g per liter of water, sprayed thoroughly on affected foliage to reduce the spread and severity of the spots.

Fruit Rot

Fruit rot in star fruit, caused by various fungi, affects both field-grown and post-harvest fruits, leading to significant losses. Effective management includes maintaining good orchard sanitation by removing and destroying infected fruits and plant debris, careful harvesting practices to minimize fruit wounds, and applying post-harvest fungicide dips such as Imazalil at 250–500 ppm or Thiabendazole at 300–500 ppm, following local regulations and guidelines to prevent fungal infections during storage and transport.

Harvesting

Maturity Indicators
Maturity Indicators: A shift in hue from green to bright yellow in sweet kinds or pale yellow-green in tart variants are some of the indicators that a star fruit is mature. The distinctive five-six star-shaped ridges stand out, frequently with a hint of browning.

Depending on the cultivar, fruits attain their maximum size. The fruit is at its best eating maturity when it is completely yellow but still firm, occasionally with faint green tips on the ridges. Fruits will soften and reach their full sweetness at this point. Overripe fruits are prone to falling and getting bruised. Fruit usually reaches maturity 60–70 days after flowering, though this might vary depending on the climate and cultivar.

Harvest Method
When collecting fruits by hand, it’s better to cut the stem near the fruit with clippers or sharp scissors. Twisting or pulling the stem could tear it and accelerate its degradation. Handle the fruits carefully to prevent bruising and surface damage.

Time of Day and Frequency
To preserve the quality of the fruit, harvesting should be done early in the morning while the temperature is lower. Fruit gradually changes color during peak season; thus picking should be done every two to four days.

Post-Harvest Handling:
After harvesting, fruits should be sorted, graded, and packed carefully. Store star fruit at around 10°C (50°F) with 85–90% relative humidity, where they can keep for 3–4 weeks. Be cautious of chilling injury, which can occur if temperatures drop below 5–7°C (41–45°F).

Yield

Cost of Investment per Acre for Star Fruit Farming

Annual maintenance cost for Star Fruit Farming

The annual maintenance cost for growing star fruit is projected to be around NRs. 50,000 per acre starting in the second year. Labor, irrigation, fertilizer and manure application, pest and disease control, pruning, weeding, and regular orchard maintenance are usually included in this cost. This investment is vital for long-term productivity and profitability since, as the trees get older and start to bear more fruit, constant maintenance is required to maintain high yields, preserve tree health, and guarantee fruit quality.

Income per Acre from Star Fruit Farming

 Analysis of Star Fruit Farming Profit Per Acre

The profit analysis of star fruit farming reveals that the break-even point is achieved in the 5th year, marking the start of positive cumulative cash flow and recovery of the initial investment. The highest annual net profit is recorded during the 8th to 10th year at NRs. 532,400.

From the 11th to 20th year, the orchard delivers sustained returns ranging between NRs. 398,000 and NRs. 230,000 annually. Even after 20 years, during the low maintenance phase, the venture remains profitable with an annual return of around NRs. 62,000. Overall, the cumulative profit over 20 years comfortably exceeds NRs. 5 million per acre, highlighting the long-term profitability and viability of star fruit cultivation.

Sources

MARDI, Malaysia. (2019). Carambola Cultivation Guide.

Food and Agriculture Organization (FAO)

University of California Agriculture & Natural Resources (UC ANR)

Indian Council of Agricultural Research (ICAR)