Climate
Garlic is grown under wide range of climatic conditions. However, it cannot withstand too hot and too cold temperatures. It requires cool and moist climate during vegetative growth and bulb development stages but warm dry weather during maturity. In general, cool growing period results in higher yield than warm conditions. Exposure of young plants to 20°C or lower temperature for 1-2 months depending upon the variety hastens subsequent bulbing. Plants that are not exposed to such climatic conditions may fail to produce bulbs or produce smaller bulbs. However, longer exposure to low temperature may produce bulbils in the axils of the leaves, which reduce the bulb yield. The critical day length for bulbing is 10-12 h for short day garlic and 13-14 h for long day garlic.
Soil
Garlic can be successfully cultivated in a wide range of soil types, but well drained fertile loamy soil with a pH of 6-8 is desirable for growing this crop. Like onion, garlic is sensitive to highly acidic, alkali and saline soils and water logging conditions. Soils with high organic matter are preferred, due to their increased moisture and nutrient holding capacity.These are less prone to crusting and compaction. In heavy soils, the bulbs produced may be deformed. Bulbs become discoloured in poorly drained soils. The threshold electrical conductivity of a saturation extract (ECe) for garlic crop is 3.9 dS/m. When the ECe level exceeds this, crop yield starts declining.
Planting and harvesting time of garlic in different regions of India
| State | Season | Time of planting | Time of harvesting |
| Chhattisgarh, Gujarat, Madhya Pradesh and Maharashtra | Kharif | June-July | October-November |
| Rabi | September-November | March | |
| Tamil Nadu | Kharif | June-July | October-November |
| Rabi | October-November | March-April | |
| Karnataka | Kharif | June-July | October-November |
| Rabi | September-October | March | |
| Andhra Pradesh | Rabi | September-October | March |
| Bihar, Haryana, Punjab, Rajasthan, Uttar Pradesh and Uttarakhand | Rabi | October-November | March-April |
| Odisha and West Bengal | Rabi | October-November | March |
| Hilly areas (Long day types) | Rabi | September | May |
Field preparation
Field should be ploughed using mould board plough and tilled using cultivator 3-4 times to eliminate debris and soil clods. Organic manure equivalent to 75 kg N/ha (FYM 15 t/ha or poultry manure 7.5 t/ha or vermicomposting 7.5 t/ha) should be incorporated at the time of last ploughing and beds of appropriate size should be prepared after leveling. Mostly, flat beds of 1.5-2.0 m width and 4-6 m length are formed. But, for kharif or rainy season, flat beds should be avoided to prevent water logging. For this season, broad bed furrows (BBF) of 15 cm height and 120 cm top width with 45 cm furrow are formed, which are suitable for drip and sprinkler irrigations.
Planting
Selection of cloves is important for garlic planting. Individual cloves from seed garlic bulbs should be separated but not long before planting. Twist off the outer skins and take the cloves apart without breaking the basal plate of the cloves, as that makes them unusable for planting. With hardneck garlic, the remainder of the stem acts as a handy lever for separating the cloves. Big cloves (>1.5g) should be selected for planting. Small, diseased and damaged cloves should be rejected. Dip cloves in carbendazim solution (0.1%) just before planting to reduce the incidence of fungal diseases during establishment. Seed rate for garlic is 400-500 kg/ha. Selected cloves should be planted vertically 2 cm below soil surface with plant to plant spacing of 10 cm and row to row spacing of 15 cm.
Fertilizers and manures
Continuous cropping without addition of plant nutrients depletes native sources in soil and affects crop yield. Hence it is essential to add plant nutrients through external sources for sustainable garlic production. Organic manures add plant nutrients and improves soil organic carbon, soil physical environment and soil microbial activity.
Based on the field experiments carried out through All India Network Research Project on Onion and Garlic at different locations, application of 75:40:40:40 kg NPKS/ha along with a combination of two or three organic manures (FYM, Poultry manure and Vermicomposting) equivalent to 75 kg N/ha (7.5 t Poultry manure or 7.5 t vermicomposting or 15 t FYM/ha) is recommended for Bihar, Chhattisgarh, Gujarat, Karnataka, Madhya Pradesh, Maharashtra, Odisha, Rajasthan and Tamil Nadu (Ooty).
Application of 100:50:50:50 kg NPKS + 20t FYM/ha is recommended for Haryana, Uttarkhand and Uttar Pradesh. Recommended organic manures should be applied before last ploughing and mixed well in the soil. One third of nitrogen and full recommended dose of phosphorus, potassium and sulphur should be applied as basal at the time of planting. Remaining two third of nitrogen should be applied in two equal splits at 30 and 45 days after planting.
Micronutrient management
If the soil test shows a deficiency of any micronutrients, besides NPKS, the deficient micronutrient should also be applied to correct the deficiency. If the plant is diagnosed with micronutrient deficiency during growth stages, the deficiency should be corrected by either foliar or soil application of concerned nutrients, immediately.
• ZnSO @ 10 kg/ha as basal is recommended in areas having Zn deficiency.
• Borax @ 10 kg/ha is recommended for areas having boron deficiency.
• FYM @ 15 t/ha is recommended in areas having multi-micronutrient deficiency along with foliar application of micronutrient mixture (Fe: 2.5%, Zn: 0.3%, Mn: 1%, Cu: 1.0%, B: 0.2%) at 45 and 60 days after transplanting for increasing onion productivity.
Foliar application of major nutrients
If the crop growth is poor, foliar application of water soluble NPK fertilizers (20:20:20 or 19:19:19) in onion @ 5g/liter at 30, 45 and 60 days after transplanting is recommended for improved yield.
Biofertilizers
Biofertilizers are efficient strains of microorganisms that improve plant nutrient uptake. When applied to seed or soil, the microbes colonize the rhizosphere or the interior of the plant and promote growth by increasing availability of primary nutrients to the host plant by biological nitrogen fixation, phosphorus solubilization and stimulating plant growth through the synthesis of growth-promoting substances. Based on the experiments carried out at DOGR, biofertilizers Azospirillum and phosphorus solubilizing bacteria @ 5 kg/ha each are recommended for garlic. Recommended biofertilizers should be mixed with 100-200 kg FYM having 50% moisture and stored overnight. The mixture should be applied before planting.
Weed management
Germination of cloves will take 7-8 days, but weeds germinate in 3-4 days after planting of garlic and grow at faster rate than garlic and cover entire field. Frequent irrigation and fertilizer application to garlic crop also favour severe crop-weed competition. Weeds compete with the crop for water, soil nutrients, light and space. Garlic crop exhibits a greater susceptibility to weed competition than most other crops, mainly due to its slow growth at initial growth stages and inherent characteristics such as short stature, non-branching, sparse foliage and shallow root system. Common weeds found in garlic fields are Moth (Cyprus rotundas), Bermuda grass (Cyanidin dactyl an), Kankawa (Camelina benghalensis), Congress grass (Parthenium hysterophorus), Kantachaulai (Amaranthus spinous), Jungali chaulayi (Amaranthus viridis), Bathua (Chenopodium album), Purslane (Portulaca oleracea), Sabuni (Trianthema portulacastrum), wild Poinsettia (Euphorbia geniculata), Makra (Dactyloctenium aegyptium), Hopvine (Merremia umbellate), Foxtail grass (Cenchrus ciliaris), Signal grass (Brachiaria spp.), Khal-muriya (Tridaxpro cumbers) etc. (Fig. 2).Control of weeds at the initial growth stages is essential for getting high marketable bulb yield. Because of labour scarcity, chemical control of weeds along with cultural methods is inevitable. Application of Oxyflurofen 23.5% EC @ 1.5 -2.0 ml/L or Pendimethalin 30% EC @ 3.5-4ml/L before or at the time of planting followed by one hand weeding at 40-60 days after transplanting is recommended for efficient weed control.
Irrigation
Garlic being a very shallow-rooted bulb crop needs frequent irrigation. It is very sensitive to moisture stress particularly during bulb initiation and bulb development. Garlic crop should be irrigated immediately after planting and subsequently at 7-10 days interval depending upon the soil moisture. In general, kharif crop needs 5-8 irrigations and rabi crop 12-13 irrigations. Irrigation needs to be stopped when the crop attains maturity (10-15 days before harvest). Excess irrigation is always harmful and dry spell followed by irrigation will result in the splitting of the outer scales in garlic. Avoid waterlogged conditions at all stages as these lead to development of diseases like basal rot and purple blotch. Similarly, continuous irrigation towards maturity leads to secondary rooting which, in turn, produces new sprouts and such bulbs cannot be stored for long. With flood irrigation water loss is too high due to conveyance, seepage and percolation losses.
Modern micro-irrigation techniques such as drip and sprinkler irrigation help in saving irrigation water and improve the marketable bulb yield significantly. In case of drip irrigation, seed cloves need to be planted at a spacing of 15 x 10 cm in a broad bed furrow (BBF) of 15 cm height and 120 cm top width with 45 cm furrow. Each BBF should have two drip laterals (16 mm size) at 60 cm distance with inbuilt emitters. The distance between two inbuilt emitters should be around 30-50 cm and the discharge flow rate of 4 l/hr. The drip irrigation system helps in water, labour and fertilizer saving, and improves bulb yield by 15-25% over flood irrigation system. In case of sprinklers, the distance between two laterals (20 mm size) should be 6 m with a discharge rate of 135 l/hr.
Fertigation
Fertigation is an effective and efficient method of applying fertilizers through drip irrigation which is used as the carrier and distributor of irrigation water and crop nutrients. Application of 30 kg nitrogen as basal dose at the time of planting and the remaining in seven equal splits at weekly days interval from planting to 60 DAP through drip irrigation is recommended. Application of nitrogenous fertilizers through drip irrigation system reduces nitrogen losses by leaching into ground water, as in fertigation, fertilizer nutrients are applied in root zone as per the crop requirement thereby improving efficiency of applied fertilizer.
Cropping system
Cropping system Garlic is a shallow-rooted crop suitable for various cropping patterns including intercropping and sequential cropping, depending upon location, nature of soil and climatic conditions. Garlic may not efficiently utilize all the mineral nutrients applied to soil. The unused mineral nutrients may be leached down along with irrigation or rain water. These unused mineral nutrients present in subsoil can effectively be used by growing deep rooted crops in succeeding season. Based on the findings of field experiments, legume followed by garlic sequence is recommended for higher yield, better utilization of nutrients and for improving soil health. Legume based cropping sequences like groundnut in summer season followed by garlic in rabi season improves the soil fertility status and provides better monetary returns to the farmers.
Intercropping
Intercropping is the practice of growing two or more crops in proximity. The most common goal of intercropping is to produce a greater yield on a given piece of land by making effective use of resources without affecting the yield of the main crop. Onion crop is best suited for intercrop with paired row planting of sugar cane (Nov.-Dec. Planting) under drip irrigation system. Ridges and furrows of 90 cm distance need to be prepared for planting sugar cane. Sugarcane sets with the single bud need to be planted at 30 cm apart in the bottom of the ridges. After every two rows of sugar cane, flat bed of 180 cm need to be prepared for planting onion crops. Onion seedlings should be planted at time of sugarcane planting. Additional fertilizer nutrients required for onion crop need to be calculated and applied as per requirement. Onion crop can be harvested after 120 DAT(Days after transplanting). Sugarcane-onion intercropping system with drip irrigation saves 25-30% water.
Storage
Garlic is mainly a rabi crop harvested during March and is required throughout the year for consumption. Hence, garlic bulbs should be stored properly to meet the supply year round. Well cured (dried neck and outer skins), clean bulbs firm to the touch can be stored for 5-6 months at ambient temperature in ventilated storage structures, but with low relative humidity (< 70%). Bulbs should be graded before storage and 20-25 plants tied in bundles along with tops. The tops should be divided in three segments and interwoven tightly. Such bundles are kept in upright position in shade for curing for 15 days and hang them in dry and well-ventilated area or use forced air to dry bulbs. If the large quantity of bulbs needs to be stored, these should be arranged in 4 feet diameter circle and to a height of 3 feet. The heap diameter should be reduced gradually from 4 feet bottom to 3 feet at top while arranging the bulbs. There should be a gap between two heaps for good ventilation.
High humidity in the stores favours mould growth and rooting. Mould growth can also be a problem if the bulbs have not been well cured before storing. During storage, bulbs will eventually become soft, spongy and shrivelled due to water loss. Excessive exposure of bulbs to direct sunlight should be avoided as it causes sloughing due to excessive shrinkage.
For long-term storage, garlic can be best stored in cold store at temperatures -1°C to 0°C with low relative humidity (60-70%). Application of excess nitrogen and irrigation 15-20 days before harvesting favours sprouting of bulbs in the field. Early planting of garlic also causes sprouting. This can be prevented by optimum supply of nitrogen and stopping irrigation about 15-20 days before planting. Irradiation with 2-6 krad of cobalt 60 gamma rays has been recommended for controlling sprouting in storage. The irradiation given to bulbs within 8 weeks of harvesting (before sprout initiation) can inhibit sprouting effectively, reduce weight loss and prolong storage life for about one year. Doses higher than 10 Kr reduce diallyl disulfide content which gives typical garlic flavour.
For seed garlic, pre-harvest spraying with 0.1% carbendazim and disinfection of stores before storage reduce post-harvest losses particularly decay loss.