Square watermelons are a unique and eye-catching fruit that can add a touch of whimsy to any garden or kitchen. These geometric marvels are created by growing regular watermelons inside square-shaped molds. To grow a square watermelon, place a young developing fruit inside a cube-shaped container, allowing it to fill the space as it matures.

The process requires careful attention and monitoring to ensure the watermelon grows properly within its confined space. Gardeners must select an appropriate variety of watermelon and provide optimal growing conditions for the best results. While square watermelons are primarily grown for their novelty and aesthetic appeal, they can be just as delicious as their round counterparts.

Growing square watermelons at home can be a fun and rewarding project for gardening enthusiasts. It combines traditional cultivation techniques with a creative twist, resulting in a fruit that’s sure to impress friends and family. With the right tools and patience, anyone can try their hand at producing these distinctive square-shaped melons.

Understanding Square Watermelons

Square watermelons are a unique and visually striking fruit that defy nature’s typical spherical shape. These cubic melons were developed as a space-saving solution and have since become a luxury item and conversation starter.

History and Origin

Square watermelons were first created by Japanese farmers in the 1980s. The ingenious idea stemmed from the need to maximize storage space in small refrigerators and produce more efficient shipping methods. Farmers in Zentsuji, Japan, pioneered the technique of growing watermelons in cube-shaped molds.

The process involves placing young watermelons into square boxes as they grow. As the fruit develops, it naturally takes on the shape of its container. This method doesn’t alter the taste or nutritional value of the watermelon, only its external appearance.

Benefits and Uses

Square watermelons offer several practical advantages. Their shape makes them easier to stack and store, reducing bruising during transport. They fit neatly into refrigerators, saving space in cramped kitchens.

These cubic fruits have become popular as decorative items and gifts in Japan and beyond. Their novelty factor makes them a standout centerpiece at events or as a unique gift. Some upscale restaurants use them as eye-catching garnishes or serving vessels.

Despite their benefits, square watermelons are significantly more expensive than their round counterparts due to the labor-intensive growing process. They’re often considered a luxury item rather than a practical fruit choice for everyday consumption.

Preparation for Growing Square Watermelons

Proper preparation is essential for successfully growing square watermelons. This involves selecting quality seeds, preparing the soil, and creating optimal growing conditions.

Selecting the Right Seeds

Choose watermelon seeds known for producing smaller, compact fruits. Look for varieties like Sugar Baby or New Hampshire Midget, which are well-suited for square shaping. Purchase seeds from reputable suppliers to ensure viability and disease resistance.

Opt for hybrid varieties if you want consistent results. These often have improved traits like faster growth or better flavor. Consider the growing season in your area when selecting seeds, as some varieties mature quicker than others.

Soil Preparation and Requirements

Watermelons thrive in well-draining soil with a pH between 6.0 and 6.8. Test your soil and adjust the pH if needed using lime or sulfur. Incorporate organic matter like compost or aged manure to improve soil structure and fertility.

Mix in a balanced fertilizer before planting. A ratio of 5-10-10 or similar works well for watermelons. Ensure the soil is loose and free from rocks or debris to a depth of at least 12 inches.

Create raised beds or mounds if your soil tends to retain water. This improves drainage and warms the soil faster in spring.

Creating the Ideal Growth Conditions

Select a sunny location that receives at least 6-8 hours of direct sunlight daily. Watermelons need warmth to thrive, so choose a spot protected from strong winds.

Prepare the planting area in spring after the last frost date. Warm the soil by covering it with black plastic for a few weeks before planting. This can speed up germination and early growth.

Install a trellis or support system if you plan to grow vines vertically. This saves space and makes it easier to attach the square molds later. Ensure the structure is sturdy enough to support the weight of growing melons.

Set up an irrigation system or plan for regular watering. Consistent moisture is crucial for watermelon development, especially during fruit formation.

Planting and Initial Care

Growing square watermelons requires careful attention during the planting and early development stages. Proper germination, transplanting, and maintenance are crucial for healthy watermelon plants.

Germination Process

Start watermelon seeds indoors 3-4 weeks before the last expected frost. Use biodegradable pots filled with a high-quality seed starting mix. Plant seeds 1 inch deep, with 2-3 seeds per pot. Keep soil consistently moist and warm, ideally between 70-80°F (21-27°C).

Place pots in a sunny location or under grow lights. Seedlings typically emerge in 7-10 days. Once sprouted, thin to the strongest seedling per pot.

Ensure good air circulation to prevent damping off. Feed seedlings with a diluted liquid fertilizer every 2 weeks once they develop true leaves.

Transplanting Seedlings

Transplant watermelon seedlings outdoors when soil temperatures reach 70°F (21°C) and all frost danger has passed. Choose a sunny location with well-draining soil.

Prepare planting hills 3-4 feet apart. Mix compost into the soil to improve fertility and drainage. Dig holes slightly larger than the seedling pots.

Gently remove seedlings from their pots, taking care not to disturb the roots. Place in holes and backfill with soil. Water thoroughly after planting.

Protect young plants from pests and cold with row covers or cloches for the first few weeks.

Watering and Feeding

Watermelon plants require consistent moisture, especially during fruit development. Water deeply once or twice a week, providing 1-2 inches of water per week.

Use drip irrigation or soaker hoses to keep foliage dry and prevent fungal diseases. Mulch around plants to retain soil moisture and suppress weeds.

Feed plants with a balanced, water-soluble fertilizer every 2-3 weeks. Switch to a low-nitrogen, high-potassium fertilizer when fruits begin to form.

Monitor soil moisture regularly. Reduce watering as fruits near maturity to concentrate flavor. Avoid overwatering, which can lead to split fruits and reduced sweetness.

Shaping Square Watermelons

Growing square watermelons requires careful timing and the use of specialized molds. This unique approach transforms round melons into eye-catching cubes through strategic containment during growth.

Building the Square-Shaped Mold

To create square watermelons, you’ll need a sturdy mold. Use 6 sheets of polycarbonate plastic, each 8 inches square and at least 3/8 inch thick. Cut the sheets precisely to ensure a perfect cube shape.

Assemble the mold using:

• 4 gate hinges
• 2 hinged clasps
• Flat head machine screws with hex nuts
• 8-10 wood screws (1 to 1.5 inches long)

Secure the sides with hinges, allowing the mold to open easily. Attach clasps to keep it closed during growth. Drill small holes for ventilation and drainage.

The Timing for Encasing Watermelons

Timing is crucial when shaping watermelons. Select young, developing fruits that are still small enough to fit inside the mold. This typically occurs 2-3 weeks after the flower has been pollinated.

Gently place the immature watermelon into the mold. Ensure it’s centered and has room to grow. Close the mold carefully, avoiding damage to the vine or fruit.

Monitor the watermelon’s growth closely. It will gradually fill the mold over several weeks.

Maintenance of Molded Watermelons

Regular care is essential for successfully growing square watermelons. Check the mold daily to ensure proper ventilation and prevent mold growth. Clean any debris that accumulates inside.

Water and fertilize the plant as you would for regular watermelons. The molded fruit requires the same nutrients and care as its round counterparts.

As the watermelon grows, it may push against the mold. Ensure the clasps remain secure to maintain the square shape. Harvest the fruit when it reaches full size and the vine begins to dry, typically 70-100 days after planting.

Ongoing Care and Monitoring

Growing square watermelons requires attentive care and regular monitoring. Proper pest management, effective pollination, and careful growth tracking are essential for success.

Pest and Disease Management

Square watermelons are susceptible to various pests and diseases. Common pests include aphids, whiteflies, and cucumber beetles. Regularly inspect plants for signs of infestation. Remove pests by hand or use insecticidal soap for larger infestations.

Diseases like powdery mildew and fusarium wilt can affect watermelon plants. Ensure proper air circulation to reduce disease risk. Remove infected leaves promptly. Apply fungicides if necessary, following label instructions carefully.

Implement crop rotation to prevent soil-borne diseases. Avoid overhead watering, as wet foliage can promote fungal growth. Mulching helps suppress weeds and maintains soil moisture, reducing stress on plants.

Pollination Techniques

Watermelons rely on pollinators for fruit development. Encourage bees and other beneficial insects by planting flowers nearby. Avoid using pesticides during flowering to protect pollinators.

For small gardens, hand pollination may be necessary. Identify male and female flowers. Male flowers have thin stems, while female flowers have a small swelling at the base. Transfer pollen from male to female flowers using a small brush or by removing male flowers and touching them to female flowers.

Pollinate in the morning when flowers are fully open. Repeat the process over several days to ensure successful fruit set.

Monitoring Watermelon Growth

Track watermelon growth closely to ensure proper development. As fruits grow, gently rotate them to maintain their square shape. Check the mold or container fit regularly, adjusting if needed.

Monitor soil moisture consistently. Water deeply when the top inch of soil feels dry. Reduce watering as fruits mature to concentrate flavor.

Watch for signs of ripeness. A ripe watermelon will have a yellow spot where it touches the ground. The tendril nearest the fruit will turn brown and dry. A hollow sound when tapped indicates readiness for harvest.

Measure and record fruit size weekly. This helps predict harvest time and ensures fruits don’t outgrow their molds. Remove any misshapen or stunted fruits to focus plant energy on healthy specimens.

Harvesting and Post-Harvest Handling

Proper harvesting and handling of square watermelons ensures optimal quality and longevity. Knowing when and how to harvest, as well as proper storage techniques, is crucial for success.

Determining Ripeness

Square watermelons typically reach maturity 80-100 days after planting. Check the tendril nearest to the fruit stem; when it turns brown and dry, the watermelon is likely ripe. The bottom spot where the melon rests on the ground should be yellow, not white or pale green.

Gently tap the watermelon. A ripe fruit produces a hollow sound, while an unripe one sounds solid. The skin should be dull and hard to pierce with a fingernail. For square watermelons, observe the shape development within the mold.

Cutting and Storing Square Watermelons

Harvest square watermelons in the morning when temperatures are cooler. Use clean, sharp pruning shears to cut the stem about 2 inches from the fruit. Avoid pulling or twisting the watermelon off the vine, as this can damage both the fruit and plant.

After harvesting, rinse the watermelon to remove dirt. Store at room temperature for up to a week or refrigerate for 2-3 weeks. Keep square watermelons upright to maintain their shape. Avoid stacking to prevent bruising.

For long-term storage, cut the watermelon into cubes and freeze in airtight containers. Frozen watermelon can last up to 12 months.

Additional Gardening Tips

Growing square watermelons requires careful planning and attention to detail. Companion planting and soil management are key factors for success.

Compatible Plants and Crop Rotation

Watermelons thrive when planted alongside certain vegetables. Corn provides natural support for climbing vines, while radishes deter pests. Avoid planting watermelons near potatoes, as they compete for nutrients.

Crop rotation is essential for maintaining soil health. Follow watermelons with legumes like peas or beans to replenish nitrogen. Rotate with shallow-rooted crops like lettuce or spinach the next season.

Consider these compatible plants:

• Sweet corn
• Radishes
• Nasturtiums
• Marigolds

Avoid planting near:

• Potatoes
• Squash
• Pumpkins

Enhancing Soil Fertility for Future Seasons

Improving soil fertility ensures robust growth for future plantings. After harvesting square watermelons, plant cover crops like clover or rye to prevent erosion and add organic matter.

Soil testing helps identify nutrient deficiencies. Address imbalances with organic amendments:

• Compost: Improves soil structure and adds nutrients
• Bone meal: Boosts phosphorus levels
• Kelp meal: Provides trace minerals

Apply a 2-3 inch layer of organic mulch to conserve moisture and suppress weeds. Rotate deep-rooted crops with shallow-rooted ones to maintain soil structure and nutrient balance.