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Why Do Watermelons Split on the Vine?

By Rhonda Abrons
Watermelon is a highly anticipated summer treat.
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Vine-ripened watermelons are a clear confirmation that summer has arrived. Plant stresses such as pests, leaf diseases and poor nutrition will affect the health and taste of watermelons. According to the University of Minnesota, irregular watering patterns alter the quality of sugar and cause watermelons to split on the vine before maturing.

Water Melons Deeply

Watermelons need large drinks of water, at least 1 to 2 inches deep, weekly. Shallow watering that only wets the soil can cause fruit rot and other unsightly blemishes. Watermelon deprived of sufficient water when fruits are young may develop blossom end rot or end up small and malformed. Blossom end rot is caused by calcium deficiency. Maintaining water levels frees calcium to be used by the plants. Drip irrigation is recommended to deliver water to plants without leaving the soil soggy.

Water Melons Infrequently

No matter how hot the weather gets, daily watering is counterproductive to watermelon production. Watermelon roots reach far into the soil, which makes them a drought-resistant fruit. Native to Africa, watermelons do best in dry and warm weather. After the crop is established, watermelons can go for weeks without watering. At times, this is done purposefully to encourage deep root growth in younger plants.

Mulch to Conserve Moisture

Straw is an excellent mulch for watermelons.
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Mulch prevents weeds and conserves moisture during drought periods. Apply mulch before watermelons appear, to avoid handling the small fruit. Spread hay, straw or crushed leaves 6 inches thick over the whole watermelon plot. Pile mulch around the base of each plant. Melons consume a great deal of soil nutrients. Compost mulch helps supply additional nutrients. A good time to mulch is when the ground is warm and the soil recently soaked by irrigation or rainfall.

Water Reduction Prior to Ripening

Reduce irrigation before fruit ripens to avoid splitting on the vine.
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Timing is crucial when growing melons. Water can be the enemy of fruit about to mature. Consistent, even irrigation is crucial in the last two weeks of watermelon growth. Over-irrigating before fruits become ripe can cause watermelons to split on the vine. Heavy rain just before harvest is also a reason watermelons crack. According to the University of California Extension, as watermelon start to ripen they attain better flavor when watering is reduced.


About the Author


Rhonda Abrons is a writer/producer in Austin, Texas. For more than 25 years her journalism work has been published in many newspapers including the "Austin-American Statesman" and the "Boston Globe."