Growing Watermelons: Best Agricultural Practices For A Successful Harvest

Watermelon (Citrullus lanatus), is an important cucurbitaceous crop, grown in warm, tropical or subtropical climates. It is a popular fruit, especially during summer, known for its sweet and refreshing taste. The fruit is highly nutritious, rich in 92% water, 7% carbohydrates, 0.2% protein and 0.3% minerals. Uttar Pradesh, Andhra Pradesh, Tamil Nadu, Karnataka and Orissa are the major watermelon producing states in India. As per the Second Advance Estimate for 2021 – 2022, the total area under watermelon cultivation is estimated to around 1.23 lakh ha while total production is estimated to be about 3.46 million tonnes in India. Following improved agricultural practices can ensure successful watermelon harvest with increased quality and yield of fruits.  

Watermelon Crop at a Glance

Botanical Name: Citrullus lanatus

Common Name: Tarbooz (Hindi), Tarbuza (Punjabi), Kalangadi (Kannada), Tarabuja (Odia), Pucchakaya (Telugu).

Crop type: Fruit crop

Soil and Climate

A well-drained sandy loam soil with a pH of 6.0 – 7.0 is highly preferred for watermelon cultivation. Soil should be fertile and rich in organic matter. Lighter soils which warm up quickly are usually preferred for early yield while heavier soils have high vine growth but delays fruit maturity. The soil should neither crack during summer season nor waterlog during rainy season.  

Watermelon is a warm season crop and is highly susceptible to frost. It requires a longer period of warmth, preferably dry weather with abundant sunshine. 18 – 25°C of sowing temperature with optimum moisture is required for germination. An average temperature of 30 – 35°C is required for growth while temperature range of about 35 – 40°C during fruit development is ideal for good quality and sweet fruit. Cool nights and warm days can increase sugar accumulation in fruits.  

Varieties/Hybrids

Hybrid	Features
NS 295 watermelon	Type: Oval to oblong Days to maturity: 80 – 85 days Jubilee-light green with light green stripes is the rind pattern Oblong shaped fruit, deep crimson flesh colour Sweetness TSS: 11-12% Fruit size: 9-12 kg
AFA 306 watermelon	It is a vigorous and strong vine hybrid Fruits: oval round dark green with dark stripe Fruit weight: 10 –12 kgs Deep red flesh, very sweet & crispy Fruit maturity: 85 -90 days after sowing Excellent shipping quality and long shelf life Tolerant to anthracnose, downy mildew diseases
Anmol yellow watermelon	The fruit is tall globe-shaped with dark skin and vague stripes, crisp and fine quality flesh Fruit weight: 3-5 kg Strong tolerance against diseases. Harvesting: 75-80 days after sowing
Apoorva watermelon	Plant is strong with good vigour Outer rind colour is light green with dark green stripe Flesh colour is dark red with granular texture Fruit weight: 8 -10 kg Fruit is oblong in shape Has good sweetness Maturity: 90 to 100 days
URJA US-888 watermelon F1 Hybrid seeds	Early medium maturity fruit Round sugar baby type hybrid Fruit flesh is red with soft texture Resistant to fusarium disease Average fruit weight: 8 – 10kg
IRIS hybrid fruit seeds watermelon	Oblong fruit shape Fruit has glossy black skin Fruit weight: 10 – 12 kg Fruit maturity: 70 – 75 days after transplanting Sugar content: 11 to 12 brix It is suitable for long transportation
Arun 0035 watermelon	Maturity: 38-40 days of flowering Fruit shape is oblong Fruit has black exterior colour Fruit weight: 3-4 kg They are high yielding, extremely good for transportation
Pakeeza watermelon	Fruit shape: Jubilee elongated oval Maturity: 70-75 days Deep red, granular flesh texture Fruit weight: 8-10 kg 12% TSS sweetness High yield variety of fruit
PAN 2053 Spl hybrid watermelon seeds	Maturity: 55-60 days after sowing Fruit weight: 2.0-2.5 kg Fruit shape is oblong Fruit colour is blackish green Excellent sweetness, crispy & suitable for distant transportation.

 

Season

Watermelon seeds are mainly sown during mid-December to January. 

Seed rate

• Varieties:  1 – 1.5 kg/acre for small-seeded types; 2 kg/acre for large seeded types
• Hybrid: 300 – 400 gm/acre

Seed treatment

It is preferred to use pre-sprouted seeds to improve crop stand in the field. The seeds should be soaked in water overnight and should then be kept in gunny bag near a warm place. The seeds will start to germinate in about 3 to 4 days.  Treat the seeds with Trichoderma viride  at 20 gm/kg seeds or mix 5-10 ml of Pseudomonas fluorescens in 50 ml water and apply it for 1 kg seeds. It can also be treated with Metalaxyl 4% + Mancozeb 64% WP at 1 – 1.5 gm/lit water/kg seeds. 

For seedling treatment, dip the roots of seedlings in Humetsu humic acid at 4 – 5 ml/lit water or Pseudomonas fluorescens at 5 ml/lit of water.  

Land Preparation

Prepare the land to a fine tilth by ploughing.  

Sowing Depth

Sow seeds at 2 – 3 cm depth. 

Sowing methods

Watermelon can be direct-seeded or transplanted from nursery. 

1. Direct-seeded method:

Methods of sowing
Furrow method	Pit method	Hill method
Furrows are to be made 2 – 3 m apart. Sow the seeds on either side of the furrows. Dibble 2-3 seeds at each place and remove the weak seedlings after germination and keep plant to plant distance as 0.75 – 1 m along the furrows. The furrow size should be of 60 cm.	Construct pits of 60 cm diameter and 60 cm depth. Maintain pit to pit distance of about 2 – 3 m.  Then fill the pits with well decomposed FYM and soil. Sow 4 seeds per pit. Later, remove unhealthy plants and retain only 2 or 3 plants pet pit.	It is usually adopted in riverbed cultivation. Construct a pit of 30 x 30 x 30 cm at a distance of 1 – 1.5 m. Fill the pits with equal proportion of soil and FYM. Pile the soil in the form of a hill and then sow 2 seeds per hill.

Gap filling and Thinning

The seeds will germinate after 8 – 10 days of sowing. At that time, thinning is done by retaining 2 or 3 healthy seedings while removing the rest. Removed seedlings may be used for gap filling. 

2. Transplanting method:

Nursery establishment
Polybag nursery	Portrays nursery
Use polybags of 200-gauge, 0.1 m of diameter and 15 cm height. Fill the bags with 1:1:1 ratio of red soil, sand and FYM mixture.	Portrays having 98 cells can be used. Sow 1 – 2 seeds per cell.

 

1. Field preparation for transplanting seedlings: Prepare raised beds of 1.2 m width and 30 cm height for sowing. In the case of drip system, place the lateral tubes in the center of each bed. Irrigate the beds through drip system for 8-12 hrs.
2. Transplanting: Transplant 12 days old seedlings in the main field. Then, plant the seedlings in the holes made on the beds at a distance of 60 cm distance.

Fertilizer Requirement

The general dose of fertilizer recommendation for watermelon is 40:20:30 kg/acre. 

Nutrient	Fertilizer	Dosage	Stage of application
Organic	FYM	8 tons/acre	Mixed with soil during ploughing
	Neem cake	40 kg	Mixed with soil during ploughing
	Humetsu Humic acid	Drenching: 4 – 5 ml/lit water or Foliar: 2 – 2.5 ml/lit water	Soil drenching: Can be done after irrigation (or)  Foliar spray: Can be done 2-3 times at critical growth stages like root formation, branching stage & flower initiation to early fruit setting stage.
N	Urea	Basal – 43 kg Top dressing – 43 kg	Basal application: Given before or at the time of planting. Top dressing: Applied 30 – 35 days after sowing.
P	Single Super Phosphate (SSP)	125 kg	Basal
K	Muriate of Potash (MOP)	50 kg	Basal
Ca & B	Multiplex Chamak Micronutrient	Foliar: 3 gm/lit water	Start spraying with flower initiation with 2 or 3 sprays at spray interval of 20-25 days
Mg	Multiplex Moti Mg	Foliar: 0.5 gm/lit water	1st spray: 1 month after sowing or transplanting 2nd spray: 15 days after first spray
Micronutrients + Seaweed extract	Tapas Pushti All Plant Nutrient Mix	Foliar: 0.25 gm/lit water	1st spray: After 2 leaf stage 2nd spray: 15 – 20 days after first spray

(NOTE: The fertilizer should be applied in the form of a ring at 6 – 7 cm at the base of the stem) 

Fertigation of nutrients can also be provided through drip system to supplement the required nutrients.  

Fertigation Schedule

Crop Stage	DAT	Water soluble fertilizers per acre
Crop establishment stage	5 – 10 days	12:61:00 at 5 gm/lit water + V-Hume 5 ml/lit water
Vegetative stage	12 – 17 days	12:61:00 at 5 gm/lit water + Nutribuild at 2.5 – 7.5 gm/lit water
	19 – 24 days	00:52:34 at 5 gm/lit water + Allbor Boron at 1 gm/lit water
Flowering stage	26 – 32 days	13 :00 :45 at 5 gm/lit water + Gibrax Phytozyme at 1 – 1.5 ml/lit water
	33 – 39 days	00:52:34 at 5 gm/lit water +  Magnesium Sulphate at 3 – 4 gm/lit
Fruiting stage	40 – 46 days	13 :00 :45 at 5 gm/lit water
	47 – 53 days	Calcium Nitrate at 5 gm/lit water
	54 – 60 days	Sulphur Liquid 2.5 ml/lit water
Harvesting	61 – 67 days	00:52:34 at 5 gm/lit water + Allbor Boron at 1 gm/lit
	68 – 74 days	Calcium Nitrate at 5 gm/lit water + Multimax nutrient at 10 – 15 gm/lit water
	75 – 80 days	13 :00 :45 at 5 gm/lit water + Gibrax Phytozyme at 1 – 1.5 ml/lit water
	82 – 87 days	00 : 00: 50 at 5 gm/lit water + Ammonium Sulphate 3 kg

 

Irrigation

Watermelon crops have a deep tap root system, and it requires less frequent irrigation. 1st irrigation to direct sown watermelon crop can be delayed if the field has sufficient moisture. However, inadequate irrigation can result in poor germination and uneven growth. 1st irrigation for transplanted seedling is to be given immediately after transplanting and subsequent irrigation can be given at 10 – 14 days intervals.  In stage of crop growth, irrigate the crop at weekly intervals. Avoid over flooding the field. Avoid water stress especially during pre-flowering, flowering and fruiting stages. Restrict the irrigation only to the root zone areas and avoid wetting veins or vegetative parts, flowers and fruits. Stop irrigation at fruit maturity or 3 – 6 days before harvesting to maintain better sweetness and flavour of fruits. A total of 7 – 9 irrigations can be given in the entire crop duration. ‘Drip irrigation’ is highly recommended for better quality of fruit, minimizing disease and weed infestation and for water conservation.  

Pollination

Pollination is a very important step in cultivation, contributing to fruit development. Both male and flowers grow on the same plant but separately in watermelon plant.  

• Honeybees: They are the primary pollinators. Insufficient pollination results in misshapen fruits. To encourage bee activity, 1 or 2 beehives can be placed per acre. Spraying chemicals in morning hours during flowering stage should be avoided.
• Manual pollination: Hand pollination can also be done in the early morning. The stamen from the male flower should be brushed against the stigma of the female flower.

Mulching

Mulching can be done underneath fruit using straw or dry leaves. Now-a-days farmers are also using plastic sheets for mulching. It helps in moisture conservation, weed suppression and prevents fruits from being in contact with soil so as to reduce pest and disease attacks. As the crop is mainly cultivated during the period of high temperature and hot winds, mulching is necessary for watermelon cultivation.   

Pinching/Training

Pruning improves yield and quality of fruits. When vines are about 1 m, apical shoots can be removed/pinched to promote growth of side shoots. During the initial stages of fruit setting, remove the malformed, damaged or diseased fruits. Only a maximum of 4 – 5 fruits can be retained per vine which can improve fruit size and yield.  

Earthing up and Weed Management

Earthing up can be done after top dressing with nitrogen fertilizer. Keep the field free from weeds during the early stages of crop growth. Follow hand weeding at an interval of 15, 30 and 45 days after sowing.  

Use of Growth Regulators

PGR	Technical content	Dosage	Benefits	Stage of Application
Ethrel Growth Promoter	Ethephon 39% SL	1–2.5 ml/lit water	Improve coloration and accelerates uniform ripening of fruits	2 – 3 weeks after full bloom stage
Katyayani Alpha Naphthyl Acetic Acid	Alpha Naphthyl Acetic Acid 4.5% SL	0.2 ml/lit water	Induces flowering, prevents shedding of flower buds, helps in enlarging fruit size, increasing and improving the quality and yield of fruits	1st spray: During flowering 2nd spray: 20 – 30 days after first spray
Hoshi Sumitomo	Gibberellic Acid 0.001% L	1.25 ml/lit water	Increases plant size, stimulates flowers, enlarges fruit, and boosts crop yields	1st spray: 15 DAT 2nd spray: 15 – 30 days after 1st spray (30 DAT)   3rd spray: 45 DAT

 

Crop Protection Practices

Pests

Major pests of watermelon crops include red pumpkin beetle, fruit fly, thrips, aphids, whitefly, leaf eating caterpillar, serpentine leaf miner, red spider mite, cutworms and cucumber beetle. 

To get a complete guide on pests viz., stage of occurrence, identification symptoms and its management turn to this insightful article – 10 Common pests of watermelon you need to know about and how to control them 

Diseases

Major Diseases that affect watermelon crops includes;

Disease type	Diseases	Stage of occurrence
Fungal Diseases	Downy mildew	Vegetative stage
	Powdery mildew	Vegetative, fruiting stage
	Anthracnose	Vegetative, fruiting stage
	Alternaria leaf spot	Vegetative stage
	Fusarium wilt	Vegetative, fruiting stage
	Gummy stem blight	Vegetative, fruiting stage
Bacterial Diseases	Bacterial wilt	Vegetative stage
	Bacterial Fruit Blotch	Vegetative, fruiting stage
Viral Diseases	Bud necrosis disease	Vegetative stage
	Cucumber mosaic virus	Vegetative, fruiting stage

 

To know about the disease causes, symptoms and management strategies look into this article – An Ultimate Guide to Watermelon Diseases: Causes, Symptoms, and Control Measures 

Harvesting Indices

• Generally, watermelon will be ready for harvest 30 – 40 days after flowering.
• When the tendril near the stem gets dried, it indicates fruit maturity
• On thumping/tapping, if the fruit produces dull hollow sound, then the fruits are ready for harvest
• Fruit maturity is indicated when the fruit surface touching the ground shows a light yellow colour.
• The rind of the fruit becomes hard and cannot be punctured with thumbnails on maturity.

Grading

Watermelons are graded depending upon their size, appearance, symmetry and uniformity in appearance. The fruit’s surface should be bright and waxy in appearance, devoid of scars, sunburn and abrasions.  

Criteria for Range in Watermelon:

Tradable Parameters	Range I	Range II	Range III
Quality	Superior	Very good	Good
Colour, shape and size (With respect to characteristic true to variety)	Uniform	Semi-uniform	Reasonably uniform
Defects allowed (Paler part of any fruit region including bruises)	Nil	A slight defect in coloring for the paler part of the fruit which is in contact with the ground during growth period	Any defect in coloring in rind, slight abrasions/bruising, presence of cracks
Weight (kgs)	Above 5 – 10	2 to 5	Below 2
Range tolerance	5% of fruits falling in range II category	10% of fruits falling in range III category	15% of fruits with minimum standards
TSS (Optional)	Not less than 10°brix

 

Storage of Watermelon

Watermelon can be stored for about 15 days at 15°C. Lower temperature may cause chilling injury. It does not stand long transportation. During transportation in trucks, stack the fruits on dried grass to avoid damage and bruising.  It is important to not store or transport watermelons with apples, tomato, muskmelon and bananas because the ethylene produced from these fruits hastens softening and development of off-flavours to watermelon fruits. There is a high chance of losing crispiness and colour due to long period of storage.