Irrigation

Watermelons, with their long vines and large leaves, have high rates of water loss via transpiration. Consequently, they benefit from supplementary irrigation, especially when grown on light, sandy soils.

Heavy soils that have been soaked just before planting may contain sufficient moisture for average crops of watermelon without the need for additional irrigation. Watermelon has deep roots and can survive relatively dry conditions.

Melons are drought tolerant. The plants are deep rooted. Growers with limited irrigation capabilities can often increase yields with only one or two irrigations. However, they require uniform irrigation for optimum growth and yield

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Critical periods, when moisture stress is most harmful, are:

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  Before seedling emergence: Inadequate moisture at planting results in poor and uneven emergence.
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  At early bloom: Moisture shortage at bloom results in poor fruit set and misshapen fruit.
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  The last ten days before harvest: Moisture stress close to harvest greatly reduces melon size and results in rapid vine decline.

Excessive irrigation after the melons have been water stressed may result in fruit splitting.

Avoid irrigating in the late afternoon or at night to reduce foliage diseases. Do not allow the fruits to get wet while irrigating.

Reduce irrigations as fruit reach harvest stage. Watering during the ripening season may delay harvest, cause splitting and reduce sweetness. Two weeks prior to maturity irrigation should be stop.

Soil type does not affect the amount of total water needed, but does dictate frequency of water application. Lighter soils need more frequent water applications, but less water applied per application.

Watermelons respond very favorably to drip irrigation. Applying water regularly, will increase fruit set, fruit size, and yield.