Growing watermelons from seed allows you to enjoy this delicious summer treat straight from your garden. While watermelons can be grown from nursery plants, starting from seed is one of the simplest methods and can yield harvestable fruit in just 70 to 100 days. Whether you choose to start your watermelons indoors, outdoors, or in containers, here are the steps to successfully grow watermelons from seed.
Types of Watermelons to Grow from Seed
Growing watermelons from seed gives you access to unique varieties not commonly found in nurseries. With over 1,200 types of watermelons available, they generally fall into three categories based on care requirements and size.
1. Early-season or “icebox” melons are quick to mature, producing smaller watermelons perfect for refrigerators. Varieties like ‘Sugar Baby’ and ‘Early Moonbeam’ are popular choices that can be grown in larger containers.
2. Main-season melons are larger, taking longer to ripen, usually ready for harvest in 80 to 90 days. Varieties such as ‘Moon and Stars’ and ‘Orangeglo’ fall into this category.
3. Seedless watermelons, which are free of seeds, tend to have sweeter fruit and vigorous vines. They require proper pollination, usually by planting alongside seeded melons. Varieties like ‘Tropical Sunshine’ and ‘Chubbiness’ are examples of seedless watermelons.
When to Plant Watermelon Seeds
For optimal growth, watermelon seeds should be sown directly into the ground or containers, as they dislike root disturbance. However, if you live in a colder climate, starting seeds indoors can help extend the growing season.
Wait until several weeks after the last frost date when soil temperatures reach 65°F or higher before planting seeds outdoors. Indoor seeds can be started a couple of weeks earlier, but should only be moved outside once they are hardened off and temperatures are consistently above 65°F.
How to Start Watermelon Seeds Outdoors
Watermelon seeds can be planted directly in garden beds or in well-draining containers like grow bags or pots at least 5 gallons in size. When growing in pots, choose compact or bush-type varieties to prevent sprawling vines. Adding a small trellis can help manage vine growth.
1. Prepare the Soil
Watermelons require full sun, well-draining, slightly acidic soil, and ample nutrients. Enhance your soil by adding 1 to 3 inches of compost or well-rotted manure and working it into the top 6 inches of soil. For container planting, use a nutrient-rich potting mix supplemented with compost or worm castings.
2. Create Hills or Use Black Plastic
Form low hills with a 2-foot diameter to warm the soil more quickly and improve drainage. Space hills 5 feet apart if planting multiple watermelon plants. Consider using black plastic mulch to further warm the soil and suppress
1. Prepare the Planting Area: Place black plastic mulch over the hilly planting area a few days before planting to warm the soil.
2. Planting the Seeds: Plant five or six watermelon seeds per hill or 5-gallon pot, burying them about 1 inch deep. No need to soak the seeds before planting. If using plastic mulch, cut holes in the plastic big enough for water penetration. Plant five or six seeds per hole.
3. Watering: After planting, water the area and keep the soil moist as the watermelons grow. Seeds typically sprout in four to 12 days.
4. Thinning Out: Once the seeds sprout and reach a few inches in height with true leaves, clip off the weakest plants at soil level with scissors. Leave two or three watermelon seeds per hill, pot, or hole.
5. Adding Mulch: When plants develop lush growth, spread 1 to 2 inches of straw mulch over the soil. Add more mulch under the watermelon vines as they grow.
Tip: Boost watermelon growth by creating melon pits instead of hills, filling them with compost, food scraps, or organic matter, planting seeds directly, and watering deeply.
Starting Watermelon Seeds Indoors:
1. Fill Containers: Use pre-moistened seed-starting mix in biodegradable pots for more room. Watermelons need space.
2. Plant Seeds: Sow one or two watermelon seeds per pot, burying them about ½ inch deep.
3. Watering: Place seeds under grow lights and keep them well-watered.
4. Thinning: If multiple seeds were planted, thin out weak seedlings when they are a few inches tall with true leaves.
5. Transplanting: Harden off seedlings for one to two weeks when soil temperature is above 65°F, then plant into garden beds or pots. Space plants 3 to 5 feet apart, water well, and consider adding mulch and trellises.
Watermelon Care Tips:
– Watermelons need 6-8 hours of full sun daily.
– Provide about 1 to 2 inches of water per week.
– Mulch the soil for insulation.
– Keep watermelon leaves dry to prevent mildew.
– Enrich the soil with organic matter before planting.
– Use a slow-release, organic fertilizer every six weeks or as directed on packaging. Consider a nitrogen-rich fertilizer during leaf and vine growth.
Watermelons need potassium and phosphorus for fruit development after flowering. Insect pollinators are necessary for watermelon plants to bear fruit, but if these pollinators are not active in your garden, you may have to hand-pollinate the flowers. Transitioning to organic gardening methods, refraining from using pesticides, and planting melons alongside flowering plants can help increase pollinator activity. Keep an eye out for common watermelon pests like aphids, cucumber beetles, thrips, and spider mites. Companion planting can aid in pest control, or you can opt for organic soap sprays and manual removal to manage them.
While watermelons typically do not require pruning, training the vines to grow on trellises can enhance airflow and reduce the risk of mildew. If you choose this method, provide support to developing fruits by using “watermelon hammocks” made of old nylon stockings or other fabric scraps to prevent vine breakage.
Watermelons do not continue to ripen after being harvested, so it is crucial to pick them at the correct time. Look for signs such as browning of the curly tendrils near the fruit, the watermelon rind shifting from shiny to dull green, the color change of the spot where the melon contacts the soil from green to yellow, and the rind becoming firm and resistant to being dented by a fingernail. For more information, refer to the original article on Better Homes & Gardens.
