How to Grow Watermelon in Wisconsin

Growing watermelon in Wisconsin might seem like a daunting task, but with proper planning and care, you can enjoy a bountiful harvest of this refreshing summer fruit. By following the right techniques and selecting suitable varieties, you can successfully grow watermelons in Wisconsin’s climate.

Choosing the Right Watermelon Variety

One of the most crucial factors in growing watermelons in Wisconsin is choosing the appropriate variety. Different watermelon cultivars have varying maturity rates, cold tolerance, and disease resistance, making it essential to select varieties specifically suited for Wisconsin’s growing conditions.

Here’s a table comparing some popular watermelon varieties and their suitability for the region:

VarietyMaturity (Days)Cold ToleranceDisease ResistanceNotes

Sugary	80-90	High	Fusarium Wilt	Compact vines, perfect for small gardens
Crimson Sweet	90-100	Moderate	Anthracnose	Large, classic variety with sweet flavor
Northern Refresher	75-85	High	Fusarium Wilt, Anthracnose	Early maturing, ideal for short seasons
Yellow Doll	95-105	Low	None	Unique yellow flesh, sweeter flavor

Choosing the right variety is crucial for ensuring a successful watermelon harvest in Wisconsin’s climate. Consider factors like maturity time, cold tolerance, and disease resistance to make an informed decision.

Cold-Hardy Varieties

Due to Wisconsin’s cooler temperatures and shorter growing seasons, it’s essential to select cold-hardy watermelon varieties. These varieties can withstand cooler soil temperatures and have a shorter maturity period, allowing them to produce fruit before the first frost.

Some cold-hardy watermelon varieties well-suited for Wisconsin include:

• Northern Refresher
• Sugary
• Yellow Doll (if planted early and given ample growing time)

Disease-Resistant Varieties

Wisconsin’s humid summers can increase the risk of watermelon diseases, making disease-resistant varieties a wise choice. Look for varieties resistant to common watermelon diseases like:

• Fusarium Wilt
• Anthracnose
• Powdery Mildew

Varieties like Sugary, Crimson Sweet, and Northern Refresher offer excellent disease resistance, ensuring a healthier crop and higher yields.

Site Selection and Soil Preparation

Choosing the right site and preparing the soil properly are crucial steps in growing watermelons in Wisconsin. Watermelons thrive in well-drained, fertile soil and require ample sunlight exposure.

Ensure the planting site receives at least 8 hours of direct sunlight per day and has good air circulation to prevent disease buildup. Raised beds or sloping areas can improve drainage and soil warmth, which is essential for watermelon growth.

Before planting, it’s essential to conduct a soil test to determine the pH level and nutrient content. Watermelons prefer a slightly acidic soil pH between 6.0 and 6.8. If necessary, amend the soil with compost, aged manure, or a balanced fertilizer to ensure optimal nutrient levels.

Sunlight Requirements

Watermelons are sun-loving plants and require full sun exposure for optimal growth and fruit production. Aim for a planting site that receives at least 8 hours of direct sunlight per day.

In Wisconsin, it’s crucial to choose a site with maximum sun exposure, as the cooler climate can delay plant growth and fruit development.

Soil pH and Nutrients

Watermelons thrive in slightly acidic soil conditions with a pH range of 6.0 to 6.8. A soil test can help determine the current pH level and guide any necessary amendments.

In addition to the proper pH, watermelons require fertile soil rich in nutrients like nitrogen, phosphorus, and potassium. Incorporate well-rotted compost or aged manure into the soil before planting to provide essential nutrients.

Planting and Care

Proper planting and ongoing care are essential for a successful watermelon harvest in Wisconsin. Follow these guidelines for optimal growth and fruit production.

Watermelons can be grown from seeds or transplants, but direct seeding is more common in Wisconsin’s climate. Plant seeds or transplants after the last frost date, typically in late May or early June, when the soil has warmed to at least 70°F (21°C).

Planting Time and Spacing

In Wisconsin, it’s recommended to plant watermelon seeds or transplants between late May and early June, after the danger of frost has passed. The soil temperature should be at least 70°F (21°C) for optimal germination and growth.

When planting, space watermelon plants 2-3 feet apart in rows spaced 6-8 feet apart. This spacing allows for proper vine growth and air circulation, reducing disease risk.

Watering and Fertilizing

Watermelons have high water requirements, especially during fruit development. Ensure consistent moisture by providing 1-2 inches of water per week, either through rainfall or irrigation.

Fertilize watermelon plants with a balanced fertilizer or side-dress with compost or aged manure every 4-6 weeks during the growing season.

Pest and Disease Management

Like any crop, watermelons can be susceptible to various pests and diseases in Wisconsin’s climate. Common issues include:

• Cucumber beetles
• Aphids
• Powdery mildew
• Fusarium wilt
• Anthracnose

To manage pests and diseases, implement the following practices:

• Use floating row covers or insect netting to protect plants from cucumber beetles and aphids.
• Practice crop rotation and remove plant debris to reduce disease buildup.
• Apply organic fungicides or copper-based products to control powdery mildew and other fungal diseases.
• Choose disease-resistant varieties to minimize the risk of Fusarium wilt and Anthracnose.

Harvesting and Storage

Knowing when to harvest and properly storing watermelons are essential for ensuring maximum freshness and flavor.

Watermelons typically take 80-100 days to mature, depending on the variety and growing conditions. Watch for the following ripeness indicators:

• Curly tendril near the watermelon stem turns brown and dries up.
• The underside of the watermelon develops a creamy or yellow spot where it rests on the ground.
• The rind takes on a dull, matte appearance and loses its glossy sheen.

When harvesting, use a sharp knife or pruners to cut the watermelon from the vine, leaving a 2-inch stem attached to the fruit.

Ripeness Indicators

Several signs indicate when a watermelon is ripe and ready for harvesting:

• The tendril closest to the stem turns brown and dries up.
• The bottom of the watermelon develops a creamy or yellow spot where it rests on the ground.
• The rind loses its glossy sheen and takes on a dull, matte appearance.
• The watermelon feels heavy for its size and produces a dull, hollow sound when tapped.

Paying close attention to these ripeness indicators will ensure you harvest watermelons at their peak flavor and sweetness.

Handling and Storage

After harvesting, handle watermelons with care to prevent bruising and damage. Store watermelons in a cool, dry place, ideally between 50-60°F (10-15°C).

Whole, uncut watermelons can be stored for up to 2-3 weeks under optimal conditions. Once cut, watermelons should be refrigerated and consumed within 3-5 days for maximum freshness and flavor.

Conclusion

Growing watermelons in Wisconsin requires careful planning, variety selection, and proper care throughout the growing season. By choosing suitable cold-hardy and disease-resistant varieties, preparing the soil appropriately, and following best practices for planting, care, and harvesting, you can enjoy a bountiful harvest of juicy, sweet watermelons right in your Wisconsin garden. With some patience and dedication, you’ll be able to savor the delicious taste of homegrown watermelons in the heart of summer.