Watermelon seeds typically need to dry for 1-2 weeks before planting in order to allow the seed coat to fully mature and harden. Drying the seeds properly is an important step to ensure good germination rates and healthy seedlings.
How Long to Dry Watermelon Seeds Before Planting
Watermelon seeds fresh from the fruit have a very high moisture content and soft seed coats. If planted immediately, they are prone to rotting, low germination rates, and weakened seedlings. Here are some guidelines for drying watermelon seeds before planting:
- Dry seeds for 1-2 weeks before planting. This allows the seed coat to fully harden and mature.
- Spread seeds in a single layer on paper towels, screens, or trays. Make sure they are not overlapping.
- Place seeds in a warm, dry, well-ventilated area out of direct sunlight.
- Stir or turn seeds daily to ensure even drying.
- Seeds are ready to plant when they appear shriveled and brown with hard seed coats. Cut a few open to check the inside – they should be firm and white.
Drying time can vary based on climate conditions. In very humid environments, drying could take longer. Check seeds periodically until properly dried.
Well-dried watermelon seeds can be safely stored in an airtight container in a cool, dry place for up to 1 year. Only plant seeds from disease-free watermelons to ensure healthy plants.
Signs Watermelon Seeds Are Not Dry Enough
It’s important not to plant watermelon seeds before they are fully dried and cured. Here are some signs that watermelon seeds need more drying time:
- Seeds appear plump, smooth, or shiny.
- Cutting a seed open reveals a soft, pale inside.
- Pressing a seed releases moisture.
- Seeds feel flexible and can be dented when pressed.
If seeds are planted too wet, they will be prone to fungal diseases and rotting. This leads to poor germination rates. Allow wet seeds to dry further before planting.
Tips for Drying Watermelon Seeds Quickly
Here are some tips to speed up the drying process if you are impatient to plant your watermelon seeds:
- Use a dehydrator on a very low setting around 90-100°F. Stir frequently and check seeds often.
- Place seeds near a warm oven or radiator – just don’t overheat them.
- Use desiccant silica gel packets to absorb moisture, enclosed in an airtight container.
- Blow a fan over the seeds to keep air circulating.
- Dry seeds in a single layer on a baking sheet in the oven at 170°F for 15-20 minutes. Check frequently to avoid over-drying.
Take care not to overly dry the seeds as this can also damage the embryo and reduce germination rates. The key is controlled, even drying.
How to Store Dried Watermelon Seeds
Once watermelon seeds are dried, store them properly to preserve viability over time:
- Place dried seeds in an airtight container such as a mason jar or resealable plastic bag.
- Store in a cool, dry location away from direct sun such as a cupboard or pantry.
- Ideal storage temperature is around 60°F.
- Use seeds within 1 year for best germination rates.
- Label seeds with the variety and year harvested.
Avoid storing seeds in humid, hot conditions. Check stored seeds occasionally and discard any that appear moldy or rotten. With proper storage, watermelon seeds can remain viable for planting up to 5 years.
How to Test Viability of Stored Watermelon Seeds
After storing watermelon seeds for several months to a year, it is a good idea to test their germination rate before planting. Here are two simple methods:
Paper Towel Method
- Take 10 seeds and place between two damp (not soaking wet) paper towels.
- Keep the paper towels moist and in a warm location around 70°F.
- Check daily and count how many seeds sprout little roots.
- Seeds with germination rates over 90% are excellent while those under 50% may need to be discarded.
- Plant 3 seeds together in small pots or cells with seed starting mix.
- Keep mix moist and in warm location around 70°F.
- Check every few days and note how many pots have sprouted.
- Germination over 90% is optimal while less than 50% is poor.
Testing a sample of stored seeds gives you valuable information on their viability before planting the entire batch.
Planting Watermelon Seeds Outdoors
Once watermelon seeds are dried and tested, follow these tips for direct outdoor sowing:
- Plant 1-2 weeks after the last expected frost when soil is warm, at least 65°F.
- Choose a site with full sun (at least 8 hours daily) and well-draining soil.
- Amend soil with compost or aged manure before planting.
- Plant 4-6 seeds together, 1 inch deep in soil or use transplants instead.
- Space planting pockets or rows 4-6 feet apart.
- Water gently and keep soil moist until sprouted.
Transplanting instead of direct sowing can give watermelons a head start on the short growing season. Start seeds indoors 3-4 weeks before last spring frost.
Germinating Seeds Indoors
For an earlier harvest, you can get a head start on the growing season by germinating watermelon seeds indoors. Here’s how:
- Plant seeds 1⁄4-1⁄2 inch deep in seed starting mix 6-8 weeks before transplanting outside.
- Keep soil moist and at a temperature of 80-90°F for best germination.
- Seeds should sprout in 5-7 days when conditions are right.
- Move sprouted seeds to full sunlight or under grow lights.
- Transplant seedlings outside after hardening off when soil is warm, around 2 weeks after last spring frost.
Getting watermelon seedlings established early allows for a longer harvest and larger fruits. Just be sure all danger of frost is past before transplanting.
Troubleshooting Germination Issues
If you are having issues getting watermelon seeds to sprout, here are some common problems and solutions:
Seeds rotting – Soil may be too wet. Allow soil to dry out before watering again.
Seeds not sprouting – Viability may have declined over storage. Test older seeds and use fresh batch if needed.
Spindly or weak seedlings – Lack of sunlight. Move to brighter location or use grow lights to supplement.
Damping off disease – Fungus issue from overly wet soil. Allow soil to dry between waterings and ensure good airflow.
Seeds sprouting then dying – Temperature stress. Maintain consistent warmth around 80°F for best results.
Seedlings stunted – Nutrient deficiency. Use seed starting mix and fertilize once true leaves emerge.
Following the proper drying, storage, planting, and care guidelines will help avoid many issues with germination and produce healthy watermelon plants!
Optimal Conditions for Growing Watermelons
Once seedlings are sprouted, here are the optimal growing conditions for watermelons:
- Sunlight: At least 8 hours of direct sun daily.
- Soil: Well-draining, sandy loam soil rich in organic matter.
- pH: Ideal range is 6.0-6.8.
- Temperature: Minimum soil temp of 65°F to sprout. Ideal growing temp is 80-90°F.
- Water: Consistent moisture is needed while fruits are developing. Provide 1-2 inches per week.
- Fertilizer: Fertilize when vines begin to run using a balanced 10-10-10 formula.
Watermelons thrive with plenty of sun, heat, and moisture. Ensure vines get adequate water while fruits are enlarging to maximize size.
Days to Maturity for Watermelon Varieties
|Days to Maturity
|Moon and Stars
Maturity times for watermelon varieties range from 75 days for early types like Sugar Baby up to 100 days for large melons like Congo. When planning, choose an early variety if you have a shorter growing season.
Troubleshooting Issues While Growing Watermelons
Watermelons thrive when given adequate warmth, sunlight, and water. However, they can encounter problems while growing. Here are solutions for common issues:
Poor germination – Ensure indoor or soil temperatures are warm enough (80°F optimal). Test stored seed viability.
Stunted vines – Could indicate cool temperatures. Cover plants if needed to retain warmth.
Slow growth – Watermelons require consistent moisture while fruits are developing. Water more frequently.
Flowers not setting fruit – Lack of pollination. Help pollinate by hand using a brush or introduce bee hives nearby.
White spots on leaves – Indicates powdery mildew fungus. Improve airflow and reduce watering. Dust sulfur can help control.
Rotten fruit – Either fungal disease or splitting from inconsistent watering. Improve drainage and irrigation practices.
Catching problems early and adjusting care allows you to get back on track for a successful harvest of sweet, juicy watermelons.
Properly drying and storing watermelon seeds is crucial to ensure good germination rates and healthy plants. Allow fresh seeds to dry for 1-2 weeks until brittle and brown. Store in a cool, dry place for up to one year. When ready to plant, provide warm soil temperatures, plenty of sunshine and adequate moisture. Grow heat-loving watermelons in full sun and fertile soil for your best harvest. With the right conditions and care, you can enjoy homegrown watermelons all season long.