Crop name: Watermelon

Scientific name: Citrillus lanatus

Family name: Cucurbitaceae

Cultivar groups: Sugar Baby, Charleston Gravy, Crimson, etc.

Warm season or cool season: Warm season


Space between plants/between rows: Plant seeds ½-1” deep, 18-24” apart in groups of three. Thin later on to best plant per bunch. Rows 5-6 feet apart.

Fertility requirements: Sandy loam soil. pH of 6.0-6.5. Watermelon are heavy feeders, requiring different fertilizer needs depending on their stage of growth. General fertilizer ratios are 5-10-10 at a rate of 15 pounds per 500 square feet.

Watering needs: Likes a well drained soil. Water infrequently and deeply, 1-2 inches per week. Use drip irrigation when possible.

Number of days from seed to transplant and/or seed to harvest: Short season variety: 65-75 days. Full season variety: 85 days.

Planting instructions: Direct seed or transplant?

  • Direct seed
  • Also does well with transplanting


Insect pest considerations: Squash Bugs, Squash Vine Borers, and Striped Cucumber Beetles.

Plant pathogen considerations: Damping off, Bacterial Wilt, Powdery Mildew, Fungal Leaf Spot.


Harvest and post-harvest guidelines: Look for tendrils near fruit turning brown as a sign of ripeness. Look for surface of fruit to be rough with dulling color, bottom starting to yellow. To harvest, twist fruit on vine until it breaks off. Do not wait for melon to separate on its own, as this is when the melon is at its peak maturity and sweetness (full slip stage). Can be stored for 1-2 weeks after picking if kept at 45-50 degrees fahrenheit.

How to harvest: melons should be cut from the vine, not pulled off as the melons could crack. Don’t stack the melons on the blossom end to avoid physical damage. Cover harvested melons to avoid the sun damaging them.

When to harvest: Watermelons are not climacteric. Depending on the cultivar the watermelon should weigh a certain amount. The sheen on the outer skin of the watermelon will go from shiny to dull when it ripens. The yellow spot from where the melon is resting on the soil will turn green, and the melon will sound hollow when you knock on it (although not all do this). The tendril will become desiccated and brown instead of green. The fruit can also be cut in half. If the flesh is dark red, the melon is ripe, if the flesh is pink or green, it is not ripe, and if the flesh is a reddish orange, it is overly ripe. Brix tests can also help determine ripeness.

Time of day to harvest: Harvest melons in the morning, preferably before 9am/ when the sun begins to heat things up.

Best method to cool crop: Watermelons should be washed after harvest to cool them. Best method to cool watermelons is to wash them and keep them in a cool dark plays on dried plant material (hay, grasses).

Optimal Storage Temperature and Relative Humidity: The optimal storage temperature and RH for long term storage (14 days) of watermelons is 15*C at 85-90% humidity, and for short term storage, the optimal temperature and RH is 7.2*C and 85-90*C.

Common post harvest losses/problems for watermelons: cracking, bruising, blossom end rot, insect damage, physical deformations, scars, sunburns, and other abrasions can render watermelons useless and unmarketable. Storage with crops that produce ethylene should be avoided. Fungal diseases also affect watermelons post harvest (black rot, anthracnose, phytophthora, fruit rot, fusarium, stem end rot. Most common bacterial disease is soft rot.

Average yields: 10,000-70,000 lbs per acre.

Farm to YouNH Crop Data:

Year Variety Date Planted Date Harvested Days to Harvest Yield (lbs/sq. ft)
 2017 Sugar Baby Bush 5/4/17-seeded




 65-75 0.622


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