Guide to Growing Watermelon in Minnesota

Growing watermelon in Minnesota can be a challenging yet rewarding endeavor. The cold climate and short growing season may seem daunting, but with the right techniques and varieties, you can enjoy the sweet taste of homegrown watermelon right in your own backyard.

Start indoors: To give your watermelon plants a head start, it’s recommended to start the seeds indoors. About 4-6 weeks before the last frost date, sow the seeds in peat pots or trays filled with seed starting mix. Keep the soil consistently moist and place the pots under grow lights or in a sunny window to ensure proper germination.

Transplant outdoors: Once the danger of frost has passed and the soil temperature has warmed up, it’s time to transplant your watermelon seedlings outdoors. Choose a sunny location with well-draining soil. Prepare the soil by adding organic matter and creating raised beds to ensure good drainage.

Note: Watermelons thrive in soil with a pH level between 6.0 and 7.5. Test your soil’s pH level and make amendments if necessary.

Choosing the Right Varieties

When it comes to growing watermelons in Minnesota, choosing the right varieties is key. The state’s short growing season and cool climate require watermelon varieties that are adapted to these conditions.

One of the most important factors to consider when selecting watermelon varieties is the number of days to maturity. Since Minnesota has a shorter growing season, it is crucial to choose varieties that have a relatively short number of days to maturity, usually around 70-80 days. This ensures that the watermelons have enough time to ripen before the first frost hits.

Another factor to consider is disease resistance. Some watermelon varieties are more resistant to common diseases, such as powdery mildew and fusarium wilt. Choosing disease-resistant varieties can help protect your watermelon crop and increase the chances of a successful harvest.

Recommended Watermelon Varieties for Minnesota

• Minnesota Midget: This small-sized watermelon variety matures in just 70-75 days. It is perfect for Minnesota’s short growing season and has a high sugar content.
• Sugar Baby: This medium-sized watermelon variety matures in 75-80 days. It is known for its sweet, red flesh and is a popular choice among Minnesota watermelon growers.
• Early Moonbeam: This early maturing watermelon variety ripens in about 70 days. It has a pale yellow rind and sweet flesh, making it a unique and delicious option for Minnesota gardeners.

By choosing the right watermelon varieties for Minnesota’s climate and growing conditions, you can increase your chances of a successful harvest. Remember to also consider factors like days to maturity, size, and disease resistance when selecting watermelon varieties. Happy growing!

Preparing the Soil

Testing the Soil

The first step is to test the soil to determine its pH levels and nutrient content. Watermelons prefer a slightly acidic soil with a pH range of 6.0 to 6.8.

To test the soil, you can use a soil testing kit, which can be purchased from a garden supply store. Follow the instructions on the kit to collect a soil sample from your garden. Once you have your sample, send it to a laboratory for analysis or use a home soil testing kit to check the pH level and nutrient content yourself.

Amending the Soil

Based on the results of the soil test, you may need to amend the soil to create the ideal growing conditions for watermelons. If the pH level is too high, you can lower it by adding organic matter like compost or peat moss. If the pH level is too low, you can raise it by adding materials like agricultural lime.

In addition to adjusting the pH level, you may also need to add nutrients to the soil. Watermelons require plenty of phosphorus, potassium, and nitrogen. You can add these nutrients by using organic fertilizers like compost or well-rotted manure. Follow the recommended application rates on the fertilizer package to ensure that you’re adding the correct amount.

Tilling the Soil

Once you’ve amended the soil, it’s time to till it. Use a garden tiller or a garden fork to loosen the soil to a depth of at least 12 inches. This will create a loose and well-draining soil structure, which is important for watermelon root development.

Remove any rocks, debris, or weeds from the soil as you till. These can hinder watermelon growth and create competition for nutrients.

After tilling, rake the soil to create a smooth surface, free from clumps and bumps.

By properly preparing the soil before planting watermelons, you’ll give your plants the best foundation for growth. With the right soil conditions, your watermelon plants will be able to establish strong root systems and produce healthy fruits.

Planting and Caring for Watermelons

Watermelons are a delicious and refreshing fruit that can be grown in Minnesota with proper care and attention. Planting and caring for watermelons requires several key steps to ensure a successful harvest.

1. Selecting the Right Location

Choose a sunny location with well-drained soil for planting watermelons. They require at least 6-8 hours of direct sunlight each day to thrive. Avoid areas with heavy clay soil, as it can lead to poor drainage and stunt the growth of the watermelon plants.

2. Preparing the Soil

Before planting, prepare the soil by removing any weeds or grass and loosening it with a garden fork or tiller. Watermelons prefer slightly acidic soil with a pH of 6.0-6.5. Test the soil and make any necessary adjustments by adding organic matter such as compost or peat moss.

3. Planting the Watermelons

Watermelons can be grown from seeds or transplants. If starting from seeds, sow them directly into the soil after the threat of frost has passed and the soil has warmed to at least 70°F (21°C). Plant the seeds 1 inch deep and space them 2-3 feet apart, allowing for ample room for the vines to grow.

If using transplants, purchase healthy seedlings from a reputable nursery and plant them in the prepared soil, making sure to dig a hole deep enough to cover the root ball completely. Space the transplants 2-3 feet apart in rows that are 6-8 feet apart.

4. Caring for the Plants

Watermelons require regular watering throughout the growing season. Keep the soil consistently moist, but not waterlogged. Water at the base of the plants, rather than overhead, to prevent the leaves from getting wet and potentially developing fungal diseases.

As the vines grow, they will need support to prevent the fruit from sitting directly on the ground. Use trellises, stakes, or other support systems to lift the vines off the ground and provide airflow to minimize the risk of rot.

Regularly monitor the plants for pests and diseases, such as aphids, cucumber beetles, and powdery mildew. If necessary, use organic insecticides or fungicides to control these problems and protect the health of your watermelon plants.

5. Harvesting the Watermelons

Watermelons are typically ready for harvest 80-90 days after planting, depending on the variety. Look for signs of ripeness, such as a dull skin color, a yellow or cream-colored bottom, and a hollow sound when tapped. Cut the watermelons from the vine with a sharp knife, leaving a few inches of stem attached.

Once harvested, store the watermelons in a cool, dry place for up to 2 weeks. Alternatively, enjoy them immediately by cutting them open and indulging in the sweet and juicy fruit.

By following these planting and care tips, you can successfully grow watermelons in Minnesota and enjoy the delicious fruits of your labor. Happy gardening!

Protecting Watermelons from Minnesota’s Climate

Watermelons are a warm-weather crop, and growing them in Minnesota’s cooler climate can be a challenge. However, with proper care and protection, it is possible to have a successful watermelon harvest.

Selecting a Suitable Location

The first step in protecting watermelons from Minnesota’s climate is to choose a suitable location for planting. Look for a spot in your garden that gets full sun for at least 6-8 hours a day. Sunlight is crucial for the growth and development of watermelons.

Using Protective Coverings

Since watermelons require warm soil and air temperatures to thrive, using protective coverings can help create a more favorable environment. One option is to use black plastic mulch to warm up the soil. Lay the mulch on the prepared bed before planting the watermelon transplants.

In addition to mulch, you can also use row covers or cloches to protect young watermelon plants from cold temperatures and harsh winds. These coverings can create a mini greenhouse effect, trapping heat and creating a warmer microclimate for the plants.

Providing Frost Protection

Minnesota’s climate can sometimes experience late spring or early fall frosts, which can damage or kill watermelon plants. To protect your watermelons from frost, consider using frost blankets or even constructing temporary structures like hoop houses or cold frames.

Make sure to monitor the weather forecast regularly and be prepared to cover your watermelon plants when frost is expected. Covering the plants in the evening and removing the coverings in the morning can help protect them from frost damage.

Disease and Pest Prevention

Another important aspect of protecting watermelons is to prevent diseases and pests that can affect their growth and yield. Keep your garden clean and free from weeds, as they can harbor pests and diseases.

Consider using organic pest control methods, such as companion planting and biological controls, to keep pests at bay. Proper watering, avoiding overhead watering, and providing good air circulation can also help prevent diseases like powdery mildew.

Regularly monitor your watermelon plants for any signs of pests or diseases and take necessary action promptly to prevent further damage.

By implementing these protective measures, you can increase the chances of successfully growing watermelons in Minnesota’s climate. Remember to choose suitable varieties, prepare the soil properly, and provide adequate care for your watermelon plants throughout the growing season.