Watermelon is a widely grown and enjoyed fruit crop in countries around the world. Watermelons can be harvested for their succulent flesh or harvested for their seeds. These watermelon seeds are usually not eaten but rather stored for further use, either for planting new crops or for other purposes such as biomass production. In order to ensure the successful storage of watermelon seeds, they must be properly prepared and stored under the right conditions.
When to Harvest Watermelon Seeds
When the watermelon is ready to pick, it’s time to harvest those precious seeds! Typically, 35-45 days after blossoming will be all that’s needed. As a sign of ripeness, you should look for the curly tendril on the vine becoming brown and dry as well as the yellowing of the white spot near its base.
How to Harvest Watermelon Seeds
The healthiest, most productive seeds can be found within the sugary section of the fruit. However, other feasible and viable seeds should not go to waste; although they may vary in quality from that of their dominant counterpart, their potential remains just as real.
Watermelon is cut in half, the ripe pulp is separated together with seeds, and put in a non-metallic container (so that the oxidation process does not begin). The pulp with seeds is poured with water and kept for three days, causing fermentation. Then the water is drained, and the seeds are washed several times in running water to clean the pulp. The unremoved fibers will begin to decompose, which will lead to the undesirable formation of pathogenic bacteria and fungi.
Another option is to eat the watermelon, collect the seeds in a container, pour water with a drop of dish detergent, and mix thoroughly to remove sugar. Then drain on a sieve, rinse with running water, and lay out to dry.
Seed Preparation for Storage
After the seeds have been properly cleaned, they need to be dried until there is no trace of moisture. The most common method of drying them is by sun exposure; however, other options include a dehydrator or oven set at a low temperature.
Shelf Life and Storage Conditions
Once the watermelon seeds are completely dry, store them in an airtight container and keep them in a cool, dark place. The ideal temperature for seed storage is between 50-54°F (10 to 12°C). The shelf life of watermelon seeds can be quite long if they are stored correctly; up to eight years in some cases. However, be sure to check the seeds yearly for signs of deterioration. If any are present, discard them immediately. To help protect the seeds from infestation, a desiccant such as powdered milk or silica gel should be included to absorb moisture.
As the amount of time, a seed is kept in storage increases, its rate of germination dramatically decreases – as evidenced by the data below.
- 1 year – 92%
- 2 years – 90%
- 3 years – 88%
- 4 years – 86%
- 5 years – 77%
- 6 years – 56%
- 7 years – 36%