Water melon is a dry season crop with life period of 75 to 100 days depending on the varieties cultivated. Sowing of seeds commences just after north East monsoon recedes and soil temperature register at least 19 degree Celsius. The day time temperature must prevail between 20-27 degree Celsius. Extreme temperature as well as lowest chilling temperature are both detrimental to the crop growth and flowering and fruit set.

Soil PH should be between 6.5 to 7.5 with high organic matter content . Soil should not be too wet nor too dry . Excess rainfall during any of the growth stages destroy water melon completely out of field 
In Tamilnadu in south India the water melon seeds are sown direct into the soil on broad bed of the width of 1.2 M at the spacing of 1.5 M by 0.6 M row to row and plant to plant spacing in drip irrigation methods .

At this spacing one acre field covers 4444 plants. This needs seeds quantity of 1.5 kgs to 400 grams per acre depending on the verities / hybrids used 
Basal application of 10 MT of Farmyard manure or 5 MT of compost per acre before last ploughing is advised besides 140 kgs of Super phosphate and 40 kgs of Muriate of potash. By around 20-25 days after planting 50 kgs of Urea is top dressed per acre of water melon.
The watermelon needs more nitrogen during early growth stage and more potassium since fruit setting and fruit development. The potassium nitrate and Calcium Ammonium Nitrate during fruit enlargement.

The seeds germinate quickly in about 6 -7 days after sowing and the water melon vine start trailing from 3rd week. When the vine is about 1.0 to 1.5 meter we need to pinch the tip of the vines so as to encourage branching. The vines produce male flowers first that looks small and subsequently it produce female flowers that are bigger in size than male flowers. Thus 1-2 female flowers are allowed per vine. After leaving 1-2 well developing fruits near the base of the stem , all other poorly developed , shrivelled and malformed fruits are removed or better the terminal part of the vines are removed 10-15 cms away from the last fruit in the vine. This will divert all the nutrients and water directly to the fruits that grow faster and bigge.

If the watermelon does not produce flowers or produce few flowers, then it is due to water scarcity, or unusual climate or soil infertility or nutrients deficiency. In order to induce more female flowers hormone called Etheral @ 2.5 ml in 10 litre water is sprayed starting from 15th days after planting @ weekly interval for 4 times.

Insect plays a major role in pollination. In the morning hours bees activity will be more by around 9 A.M .Because in the early morning due to chill temperature bees activity will be less and as temperature raise the bees activity will raise and you can hear more buzzing of the bees around flowers in  water melon between 9- 10 AM..The female flowers open in the early morning and highly receptive for pollination during these hours when bee’s activity is more. In the evening the fertilized female flowers close. At least 8-20 bee visit per female flowers are required for effective pollination and fruit set. Cloudy weather , too wet or chill temperature or high wind speed disturb the bees  and consequently result in poor fruit set.

So by effective cultural practices  4444 water melon plants @ average of 2 numbers of fruits per plant will produce 8888 fruits . At an average individual fruit weight of 3 kgs an acre of water melon will yield about 26664. But due to variation in the innate soil fertility across the cultivation land  and other invisible risk factor we can very well realise 75% of this yield projection ie, 20,000 kgs @ the selling price of  Rs. 5 per kg an acre of watermelon can produce an income of Rs.1,00,000 in about 3.5 months time .

Note: Seed treatment in panchagavya before sowing promote early germination and vigourof the water melon plants. After panchagavya treatment that last for 12 hours,seeds are treated with Imidachlorpid or other suitable insecticide. Becauseimmediately after emergence and during first and second true leaf stage, minutesucking pest attack the young plants that later cause mortality or weak plantsand plant destiny or plant population decrease Humic acid and panchagavyaapplication through drip irrigation or foliar spray boost the yield and tasteof the melon .