10 Watermelon Growing Tips for Bigger, Juicier Fruit This Summer

How to Grow Sweeter Watermelons

1. Choose Sweeter Varieties

Some watermelon varieties naturally produce sweeter fruit than others.

Varieties such as 'Charleston Grey,' 'Bradford,' 'Crimson Sweet,' and 'Sultan' are known for high sugar content.

Seedless watermelons need to be planted alongside seeded varieties that can act as pollenizers to ensure successful fruit production.

2. Pick a Sunny Location

Heat and sunlight are major factors in determining watermelon sweetness.

Long periods of cool, cloudy weather can reduce sweetness, while hot, sunny conditions encourage the plants to produce more sugars and flavor.

Plant watermelons in full sun with at least eight hours of direct sunlight per day.

Black plastic sheeting over the soil can help warm the soil more quickly and may be useful during cooler-than-average summers.

3. Enhance the Soil

Watermelons are heavy feeders and grow best in rich, well-draining, slightly acidic soil.

Test the soil before planting and mix several inches of compost into the planting area.

Melons can also be grown in melon pits containing food scraps and other organic material that gradually supplies nutrients to the rapidly growing vines.

4. Plant at the Right Time

Watermelons are heat-loving plants and cannot tolerate cold weather.

Plant outdoors only after the risk of frost has passed, but avoid planting seeds too late because watermelons need to complete most of their growth during the hottest part of summer.

Watermelons generally require 85 to 95 days to mature.

If the growing season does not provide at least three months of warm weather, including nights above 60°F, start seeds indoors.

In warm climates, sow seeds outdoors about one to two weeks after the danger of frost has passed.

5. Water Well

Watermelon plants require regular watering and generally need about 1 to 2 inches of water per week.

Once fruit begins developing, gradually reduce watering.

Stop watering completely about two weeks before harvest if conditions allow. Excessive watering during fruit development can dilute the sugars and make the watermelons less sweet.

6. Fertilize Regularly

Compost-enriched soil can support watermelon growth, but additional fertilizer may be needed because watermelons are heavy feeders.

Apply granular fertilizer approximately every six weeks or liquid fertilizer about every two weeks.

Always follow the application rates and instructions provided on the fertilizer label.

7. Prevent Fungal Issues

Powdery mildew and other fungal diseases can develop when humidity is high and watermelon plants are crowded.

Although fungal problems are rarely fatal, they can reduce plant productivity and fruit quality.

Follow recommended plant spacing and water at the soil line rather than overhead to reduce fungal problems.

For recurring powdery mildew, a milk spray can be used. Mix 40% milk with 60% water in a garden sprayer and apply it thoroughly to the watermelon plants once a week.

8. Prune Wisely

Avoid extensive pruning because removing too many leaves reduces the plant's ability to photosynthesize and produce the sugars that contribute to sweet fruit.

However, removing some excess flowers and fruit can allow the plant to direct more energy toward the remaining watermelons.

Once a vine has three to four developing watermelons, remove additional flowers and fruit that form afterward.

9. Watch for Pests

Pests can stress watermelon plants and reduce their ability to produce large, flavorful fruit.

Monitor plants regularly so pest problems can be detected early.

For aphids and spider mites, spray plants with a strong stream of water or use insecticidal soap.

Companion planting with flowers and scented herbs can also help. These plants may discourage pests and attract beneficial insects and pollinators, which can improve fruit set.