How to Grow Watermelons in Iowa

Gardening in the Zone: Growing Melons

Introduction

If you’re a gardener in Iowa looking to grow watermelons in your backyard or farm, you’ve come to the right place. Watermelons thrive in warm temperatures and sunny conditions, making Iowa’s summer climate suitable for their cultivation. By following the steps outlined in this article, you can successfully grow watermelons in Iowa and enjoy the sweet, refreshing fruit throughout the season.

Choosing the Right Watermelon Variety

Selecting the appropriate watermelon variety is crucial for a successful harvest in Iowa’s climate. Look for disease-resistant and early-maturing cultivars that can withstand cooler temperatures and have a shorter growing season. Here are some popular watermelon varieties well-suited for Iowa:

VarietyDays to MaturityDisease ResistanceNotes

Sugar Baby	70-85 days	Anthracnose, Fusarium Wilt	Small, icebox-type watermelon
Crimson Sweet	85-90 days	Anthracnose, Fusarium Wilt	Large, oblong shape, sweet flesh
Seedless Red	90-100 days	Fusarium Wilt	Seedless variety, requires pollinator plant
Yellow Doll	75-85 days	Anthracnose, Fusarium Wilt	Yellow-fleshed watermelon with sweet flavor

Early-maturing varieties like Sugar Baby and Yellow Doll are excellent choices for Iowa’s shorter growing season, while larger cultivars like Crimson Sweet may require a longer, warmer period to fully ripen.

Preparing the Soil

Watermelons thrive in well-drained, nutrient-rich soil with a slightly acidic to neutral pH range of 6.0 to 7.0. To prepare the soil for planting, follow these steps:

• Test the soil’s pH level and amend it if necessary with lime or sulfur to reach the desired range.
• Incorporate plenty of organic matter, such as well-rotted compost or aged manure, into the soil to improve its fertility and water-holding capacity.
• Create raised beds or hills to ensure proper drainage and warmth for the watermelon plants.
• Apply a balanced fertilizer or aged manure to the planting area before sowing or transplanting.

Planting Watermelon Seeds

Proper planting techniques are essential for successful watermelon growth in Iowa. Here are the key steps to follow:

• Direct sowing is recommended for watermelons in Iowa. Plant the seeds 1 to 2 inches deep and 3 to 4 feet apart in rows or hills, spacing the rows 6 to 8 feet apart.
• For an earlier harvest, start seeds indoors 3 to 4 weeks before the last expected frost date. Transplant the seedlings into the garden after hardening them off and when the soil has warmed to at least 70°F.
• Aim to plant watermelon seeds or transplants after the last spring frost, typically in late May or early June in Iowa.

Direct Sowing vs. Transplanting

While direct sowing is the preferred method for watermelons in Iowa, transplanting seedlings can provide an earlier harvest. However, transplanting requires extra care and attention to avoid transplant shock and ensure successful establishment.

Protecting Young Plants

Young watermelon plants are susceptible to various threats, including pests, frost, and adverse weather conditions. To protect your plants:

• Use row covers or cold frames to shield them from late spring frosts and cool temperatures.
• Apply organic mulch around the plants to conserve moisture and suppress weeds.
• Implement pest management strategies (discussed later) to deter insect pests like cucumber beetles and aphids.

Caring for Watermelon Plants

Proper care and maintenance are crucial for healthy watermelon plant growth and fruit production.

Watering Techniques

Watermelons have high water requirements, especially during fruit development. Here are some watering tips:

• Water deeply and consistently, providing 1 to 2 inches of water per week, depending on rainfall.
• Avoid overhead watering, which can promote fungal diseases. Instead, use soaker hoses or drip irrigation systems.
• Mulch around the plants to conserve soil moisture and reduce water needs.
• Signs of over-watering include yellowing leaves and fruit cracking, while under-watering can lead to wilting and reduced fruit size.

Fertilizing and Mulching

Watermelons benefit from regular fertilization and mulching throughout the growing season:

• Apply a balanced fertilizer or aged manure every 4 to 6 weeks, following the recommended rates on the product label.
• Spread a 2 to 4-inch layer of organic mulch, such as straw or shredded leaves, around the plants to retain moisture and suppress weeds.

Pest and Disease Management

Watermelons can be susceptible to various pests and diseases in Iowa. Implementing an integrated pest management (IPM) approach is crucial for maintaining healthy plants and ensuring a bountiful harvest.

Common Pests

• Cucumber Beetles: These striped or spotted beetles can transmit bacterial wilt and feed on watermelon leaves and stems.
• Aphids: These small, pear-shaped insects can infest watermelon plants and transmit viruses.
• Squash Bugs: These brown, stink-bug-like insects feed on watermelon leaves and stems, causing wilting and stunted growth.

Common Diseases

• Fusarium Wilt: This soil-borne fungal disease causes yellowing, wilting, and eventual plant death.
• Anthracnose: Characterized by circular, sunken lesions on leaves, stems, and fruits.
• Powdery Mildew: A fungal disease that causes a white, powdery growth on leaves, stunting plant growth and reducing fruit quality.

Integrated Pest Management (IPM) Strategies

To effectively manage pests and diseases, implement an IPM approach that combines cultural, biological, and chemical control methods:

• Cultural control: Practice crop rotation, remove plant debris, and choose disease-resistant varieties.
• Biological control: Encourage beneficial insects like ladybugs and lacewings by planting companion plants and avoiding broad-spectrum insecticides.
• Chemical control: As a last resort, use targeted and approved insecticides or fungicides according to label instructions.

Harvesting and Storing Watermelons

Knowing when to harvest and how to store watermelons properly is essential for enjoying the sweet, juicy fruits of your labor.

Ripeness Indicators

Look for these signs to determine when your watermelons are ready for harvesting:

• The underside of the watermelon (where it rests on the ground) turns from white to creamy or yellow.
• The tendril closest to the fruit stem turns brown and dries up.
• The watermelon produces a hollow sound when tapped with your knuckles.

Harvesting Techniques

• Use a sharp knife or pruning shears to cut the watermelon from the vine, leaving a few inches of stem attached.
• Avoid pulling or twisting the watermelon off the vine, as this can damage the plant and other developing fruits.
• Handle harvested watermelons carefully to prevent bruising or damage.

Storage and Shelf Life

Proper storage can extend the shelf life of your watermelons:

• Store watermelons at room temperature (around 70°F) for up to two weeks.
• For longer storage, place whole, uncut watermelons in the refrigerator, where they can last up to four weeks.
• Once cut, watermelons should be refrigerated and consumed within a few days.

Conclusion

Growing watermelons in Iowa requires patience, attention to detail, and adherence to best practices. By selecting suitable varieties, preparing the soil properly, planting at the right time, providing adequate care, and implementing effective pest and disease management strategies, you can enjoy a bountiful harvest of juicy, sweet watermelons. Remember to monitor your plants closely, follow the recommended harvesting and storage techniques, and most importantly, savor the delicious fruits of your labor.