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Growing Watermelon

Growing Watermelon

Yellow Doll Hybrid



Watermelon is a heat-loving vining crop that produce nutritious, sweet fruit. Successfully growing watermelon requires a relatively long, warm growing season, but early maturing varieties help to expand its range. Watermelon varieties are classified by their size, shape, rind color, and whether or not they have seeds.

Picnic watermelons are large (usually 15 to 45 pounds) and round to oblong in shape, with a striped rind. Crimson Sweet is an example of a picnic type.

Icebox watermelons are smaller than picnic types (generally 5 to 15 pounds) and have round fruit. Sugar Baby is a popular icebox variety.

Personal or mini watermelons are very small (under 5 pounds) and ideal for a small family or individual serving. Solitaire Hybrid is an example of a mini variety with a white rind.

Seedless watermelons have become very popular in the US. These varieties do not produce mature seeds (though the usually produce immature, white seeds). Seedless varieties are triploid (have three sets of chromosomes), so they do not produce fertile pollen and require a seeded variety to serve as a pollinator in order to produce fruit. A variety with a contrasting rind color is used as a pollinator, to make identifying seedless fruit easy. Pollinator seed is included in a glassine envelope inside the packet of seedless watermelon. Plant one pollinator plant for every 2 to 3 seedless plants in the garden. Summer Sweet 5234 Plus Hybrid is a seedless variety.

How To Plant

Watermelon seed can be sown directly in the garden or started indoors 2 to 4 weeks early for faster production. For direct sowing, plant seed outdoors a week or two after the last frost in spring, when soil temperature has warmed. Because seedless watermelon varieties are slower to germinate than seeded types and benefit from higher soil temperatures, they are best started indoors. Germinate seeded watermelons at 68 to 90 F and seedless types at 80 to 95 degrees. Expect germination in 7 to 21 days.

Plant the seed half an inch to an inch deep.

When planting in rows, space plants 2 to 3 feet apart with 6 to 9 feet between rows. For planting in hills, space hills 6 to 8 feet apart. Plant 4 to 5 seeds per hill and thin to the 3 strongest seedlings.


Watermelons thrive in hot, sunny conditions. The plants benefit from mulching to help keep soil evenly moist and reduce weed problems. 

It can be somewhat challenging to identify when watermelons are at their peak ripeness, as they do not "slip" from vines like muskmelons do. To identify when watermelons are ripe, first look at the grasping tendril closest to the fruit stem. The tendril will start to dry up and turn brown when the melon is ripe. Another indicator of ripeness is the bottom of the fruit, where it sits on the soil, will change color to yellowish.

Fertilizer Recommendations

Watermelon is a heavy feeder that benefits from regular fertilization. Use full rates of ALGOplus Tomato, Purple Cow BioActive All-Purpose, or Neptune's Harvest Tomato & Veg.

Common Problems

A few pests and diseases may affect watermelon. Aphids, cucumber beetles, mites, pickleworms, and squash vine borers can be insect pests. Potential diseases include downy mildew, powdery mildew, and fusarium wilt. Fortunately, watermelons are resistant to the bacterial wilt disease that cucumber beetles can spread.

Alternative Products

Muskmelons are another type of melon with similar culture to watermelon.

Complimentary Products

Weed Control Porous Film Mulch can be used to control weeds and warm the soil. Floating Row Covers can be used to protect newly planted seedlings from cold temperatures and insects for the first 3 to 4 weeks of growth.

Product Recommendations

Seeds can be started indoors in plantable 4 Inch Round Jiffy Peat Pots or Super Size Jiffy-7 Plant StartersCaptain Jack's Deadbug Brew can be used to control insect pests. Use 70% Neem Oil or Serenade organic fungicide to prevent disease infection.

Watermelon Facts

The scientific name for watermelon is Citrullus lanatus in the family Cucurbitaceae, so it is related to cucumbers, muskmelons, and squash. Watermelon is thought to have originated in Africa. The current Guinness World Record for the heaviest watermelon is 350.5 pounds, and was awarded in 2013 to a grower in Tennessee.

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