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How to Cultivate Onions in India: Best Practices and Crop Calendar

Onions are one of the most popular and widely consumed vegetables in India. They are also a profitable crop for farmers, as they have a high demand and a long shelf life. However, growing onions requires some knowledge and skills, as they are sensitive to soil, climate and pest conditions. In this blog post, we will share some tips and guidelines on how to cultivate onions in India, based on the best practices and crop calendar recommended by experts.

Soil and Climate Requirements

Onions can be grown in a variety of soils, ranging from sandy loam to clay loam, as long as they are well-drained, fertile and rich in organic matter. The optimum pH range for onion cultivation is 6.0-7.5, but they can also tolerate mild alkaline soils. Onions do not grow well in highly acidic, saline or waterlogged soils.

Onions are a temperate crop, but they can adapt to different climatic conditions, such as tropical, subtropical and cool climates. They need a lower temperature (13-24°C) and a shorter day length (10-12 hours) for vegetative growth, and a higher temperature (16-25°C) and a longer day length (13-14 hours) for bulb development and maturity. They can withstand light frost in the young stage, but not extreme heat or cold. They also need adequate rainfall (650-750 mm per year) with good distribution during the monsoon season.

Season and Varieties

In India, there are three main seasons for onion cultivation: kharif, late kharif and rabi. The kharif season starts from July-August and ends in October-December; the late kharif season starts from October-November and ends in January-March; and the rabi season starts from December-January and ends in March-May. The rabi season is the most suitable for onion production, as it has less pest and disease problems, higher yield and better quality.

There are many varieties of onions available in India, depending on the season, region and market preference. Some of the popular varieties are:

Kharif season: Agrifound Dark Red, Agrifound Light Red, Arka Niketan, Arka Kalyan, Bhima Kiran, Bhima Shakti, Bhima Shweta, NHRDF Red-2 etc.
Late kharif season: Agrifound Dark Red, Agrifound Light Red, Arka Kalyan, Bhima Kiran, Bhima Shakti etc.
Rabi season: Agrifound Dark Red, Agrifound Light Red, Arka Kalyan, Arka Niketan, Bhima Kiran, Bhima Shakti, Bhima Shweta, NHRDF Red-3 etc.

Sowing Method and Spacing

Onions can be propagated by seeds or bulbs (sets). Seeds are preferred for rabi season, as they produce bigger and uniform bulbs. Bulbs are preferred for kharif and late kharif seasons, as they mature faster and have less bolting problems. Seeds can be sown directly in the field or in nursery beds. Nursery beds should be prepared with well-decomposed organic manure and fine soil. Seeds should be sown at a depth of 1-2 cm and covered with a thin layer of soil or straw mulch. The seed rate is 8-10 kg per hectare for direct sowing and 4-5 kg per hectare for nursery raising. The seedlings will be ready for transplanting in 45-50 days after sowing.

Transplanting should be done in flat beds or raised beds with proper drainage channels. The spacing between rows should be 15 cm and between plants should be 10 cm for both seeds and bulbs. The planting depth should be 2-3 cm for seeds and 4-5 cm for bulbs. The transplanted seedlings or bulbs should be watered immediately after planting.

Manuring and Fertilization

Onions need adequate nutrition for good growth and yield. Organic manure should be applied at the time of land preparation at the rate of 20 tonnes per hectare or 10 tonnes of farmyard manure (FYM) plus 5 tonnes of poultry manure or vermicompost per hectare. Chemical fertilizers should be applied based on the soil test results and the season. The general recommendation is:

Kharif season: 100:50:50:50 kg of NPKS per hectare
Late kharif season: 150:50:50:50 kg of NPKS per hectare
Rabi season: 150:50:80:50 kg of NPKS per hectare

Half of the nitrogen and the full dose of phosphorus, potassium and sulphur should be applied as basal dose before planting. The remaining half of the nitrogen should be applied in two splits at 30 and 45 days after transplanting. The top dressing should be done before the bulb development stage. Micro-irrigation and fertigation can also be used for efficient water and nutrient management.

Intercultural Operations

Onions need regular weeding and hoeing to keep the field free from weeds and to aerate the soil. The first weeding should be done 15-20 days after transplanting and the subsequent weedings should be done at 15-20 days interval. Hand weeding or mechanical weeding can be done depending on the availability of labour and machinery. Mulching with organic materials such as straw, grass, leaves etc. can also help in reducing weed growth and conserving soil moisture.

Onions may also need earthing up or hilling up to prevent the exposure of bulbs to sunlight and to prevent green colouration. Earthing up should be done 60-70 days after transplanting when the bulbs are fully developed. The soil should be drawn towards the plants to cover the necks of the bulbs.

Irrigation

Onions need frequent irrigation due to their shallow root system. The irrigation frequency and quantity depend on the soil type, climate and growth stage of the crop. The general guideline is to irrigate the crop at 7-10 days interval during the vegetative stage and at 4-5 days interval during the bulb development stage. The irrigation should be stopped 10-15 days before harvesting to facilitate curing and drying of the bulbs. Furrow irrigation is preferred over overhead irrigation, as it reduces the risk of foliar diseases and water loss.

Pest and Disease Management

Onions are susceptible to various pests and diseases that can reduce the yield and quality of the crop. Some of the common pests are:

Thrips: These are tiny insects that suck the sap from the leaves and cause silvering, curling and drying of the leaves. They also transmit viral diseases such as onion yellow dwarf virus and iris yellow spot virus. They can be controlled by spraying insecticides such as dimethoate, imidacloprid, spinosad etc.
Cutworms: These are caterpillars that feed on the stems and roots of young plants at night and cut them off at the soil level. They can be controlled by applying insecticides such as chlorpyriphos, carbaryl, cypermethrin etc.
Bulb mites: These are microscopic mites that feed on the bulbs and cause decay, rotting and reduced storage life. They can be controlled by dipping the bulbs in hot water (50°C) for 15 minutes before planting or by applying acaricides such as dicofol, propargite, fenazaquin etc.

Some of the common diseases are:

Purple blotch: This is a fungal disease that causes purple spots on the leaves and stems, followed by blighting and drying of the foliage. It can be controlled by spraying fungicides such as mancozeb, chlorothalonil, carbendazim etc.
Stemphylium blight: This is a fungal disease that causes brown spots on the leaves and stems, followed by blighting and drying of the foliage. It can be controlled by spraying fungicides such as mancozeb, chlorothalonil, carbendazim etc.
Basal rot: This is a fungal disease that causes yellowing and wilting of the leaves, followed by rotting of the bulbs at the base. It can be controlled by applying fungicides such as carbendazim, thiophanate methyl, captan etc.

Harvesting and Storage

Onions are ready for harvesting when 50-75% of the leaves fall over and turn yellow or brown. The maturity of onions can also be judged by pressing the necks of the bulbs with fingers. If they are soft and easily bent, they are mature enough for harvesting. Harvesting should be done carefully to avoid damage to the bulbs. The bulbs should be lifted with a spade or a fork and kept in the field for curing and drying for 7-10 days under shade or cover.

After curing, the bulbs should be cleaned from soil, roots and dried leaves. The bulbs should be graded according to their size, shape, colour and quality. The graded bulbs should be packed in mesh bags or crates for storage or marketing. Onions can be stored for 3-6 months under proper conditions. The storage temperature should be 0-5°C with 65-70% relative humidity for long-term storage. The storage place should be well-ventilated, dark and rodent-proof.