How to Grow Watermelon in Winter

Growing melons in a cold climate: protecting the fruit

Growing watermelons in winter is a challenging endeavor, but with the right techniques and optimal conditions, it is possible to cultivate these refreshing fruits even during the coldest months. By following specific guidelines for variety selection, environmental control, planting, and care, you can successfully grow watermelons in winter and enjoy their sweet, juicy flesh year-round.

Choosing the Right Watermelon Variety

The first step in growing watermelons in winter is selecting the appropriate variety. Standard watermelon varieties that thrive in warm weather may not perform well in cooler conditions. Instead, look for compact, early-maturing, and cold-hardy varieties specifically bred for winter cultivation.

Sugar Baby Variety

The Sugar Baby watermelon is an excellent choice for winter growing. This compact variety produces round, sweet melons weighing 6-10 pounds. Known for its early maturation and tolerance to cooler temperatures, the Sugar Baby watermelon is well-suited for greenhouse or indoor cultivation during the winter months.

Yellow Baby Variety

Another top pick is the Yellow Baby watermelon. This disease-resistant variety bears small, round, yellow-fleshed melons weighing 6-8 pounds. With its early-bearing nature and ability to thrive in cooler conditions, the Yellow Baby watermelon is an ideal option for winter cultivation.

Creating the Ideal Growing Environment

Providing the right environmental conditions is crucial for successful winter watermelon cultivation. These vining plants require warmth, protection from harsh weather, and consistent humidity levels to thrive.

Greenhouse or Cold Frame

To grow watermelons in winter, a greenhouse or cold frame is essential. These structures create a controlled, protected environment, shielding the plants from freezing temperatures, wind, and precipitation. Ensure the greenhouse or cold frame is well-insulated and equipped with proper ventilation and heating systems.

Supplemental Heating

Watermelons require consistent warmth to grow and set fruit. In a greenhouse or indoor setting, supplemental heating is necessary to maintain optimal temperatures between 70°F and 85°F (21°C and 29°C). Various heating options are available, such as soil cables, space heaters, or even a wood stove, depending on the size of your growing area.

Humidity and Ventilation

Watermelons thrive in humid conditions, with relative humidity levels between 60% and 70%. To maintain these levels, you may need to install humidifiers or use evaporative coolers in your greenhouse. Additionally, proper ventilation is crucial to prevent the buildup of excess moisture, which can lead to fungal diseases.

Planting and Care

Proper planting techniques and ongoing care are essential for successful winter watermelon cultivation.

Soil Preparation

Watermelons prefer well-draining, nutrient-rich soil with a pH range of 6.0 to 6.8. Before planting, amend the soil with compost, aged manure, or a balanced fertilizer to provide the necessary nutrients for healthy growth. Ensure the soil has excellent drainage to prevent waterlogging, which can lead to root rot.

Planting and Spacing

Start watermelon seeds indoors 4-6 weeks before the desired transplanting date. Plant seeds 1 inch deep in seed-starting trays or pots filled with a sterile seed-starting mix. Once the seedlings have developed their first true leaves, transplant them into the prepared growing area, spacing them 2-3 feet apart in rows spaced 6-8 feet apart.

Watering and Fertilizing

Watermelons have high water requirements, especially during fruit development. Water the plants deeply and consistently, keeping the soil evenly moist but not waterlogged. Apply a balanced, water-soluble fertilizer every 2-4 weeks, following the manufacturer’s instructions for proper application rates.

Pollination

In a greenhouse or indoor setting, hand-pollination may be necessary for successful fruit set. Use a soft-bristled brush or cotton swab to transfer pollen from the male flowers to the female flowers daily. Alternatively, you can introduce pollinator insects, such as bees or Mason bees, into the growing area to facilitate natural pollination.

Pest and Disease Management

Like any crop, watermelons are susceptible to various pests and diseases, which can become more problematic in the confined environment of a greenhouse or indoor growing area.

Common Pests

PestPrevention and Control Methods

Aphids	– Use insecticidal soaps or neem oil
	– Introduce beneficial insects like ladybugs or lacewings
Spider Mites	– Maintain proper humidity levels
	– Use insecticidal soaps or horticultural oils
Whiteflies	– Use yellow sticky traps
	– Introduce parasitic wasps

Common Diseases

• Powdery Mildew: Maintain proper air circulation, avoid overcrowding, and use fungicides if necessary.
• Fusarium Wilt: Plant disease-resistant varieties, practice crop rotation, and ensure proper soil drainage.
• Anthracnose: Remove infected plant material, maintain proper spacing, and apply fungicides as a preventative measure.

Harvesting and Storage

After investing time and effort into growing watermelons in winter, it’s essential to know when and how to harvest and store the fruits properly.

Harvesting Tips

• Look for the tendril closest to the fruit stem to turn brown and dry, indicating maturity.
• Give the watermelon a gentle tap; a dull, hollow sound means it’s ripe.
• Check the bottom of the watermelon for a creamy or yellow spot, which indicates readiness for harvesting.
• Use a sharp knife or pruners to cut the stem, leaving 2-3 inches attached to the fruit.

Storage Methods

Watermelons can be stored at room temperature for up to two weeks or refrigerated for up to three weeks. Here are some tips for longer storage:

• Avoid bruising or cutting the watermelon before storage.
• Wrap uncut watermelons in plastic wrap or store them in a perforated plastic bag.
• Cut watermelons should be tightly wrapped or stored in an airtight container in the refrigerator.

Conclusion

Growing watermelons in winter may seem like a daunting task, but with the right knowledge and techniques, it is entirely possible to cultivate these sweet, refreshing fruits year-round. By selecting suitable varieties, creating an optimal growing environment, following proper planting and care guidelines, and managing pests and diseases effectively, you can enjoy the rewards of homegrown watermelons even during the coldest months. Embrace the challenge of winter watermelon cultivation and savor the delicious fruits of your labor.