How to Grow a Square Watermelon in 2025: A Complete Guide

 

Growing watermelons is a popular gardening activity for many enthusiasts, especially during the hot summer months. The refreshing, juicy fruit is loved by people of all ages, and cultivating it in your own garden brings a special sense of accomplishment. 

But what if you could take your watermelon-growing skills to the next level? What if you could grow a square watermelon? Yes, you heard that right! Square watermelons are a unique and fascinating variation that has gained popularity in recent years, especially in Japan, where it originated as a form of art and innovation in farming.

In this comprehensive guide, we’ll walk you through the entire process of growing square watermelons, from selecting the right watermelon variety to the techniques involved in shaping the fruit. Whether you’re growing them for novelty purposes, as a gift, or just for fun, this guide will provide you with all the information you need to create your own square watermelons in 2025.

What is a Square Watermelon?

A square watermelon is a watermelon that has been shaped into a square, as opposed to the traditional round or oval shape that we’re all familiar with. While square watermelons do occur in nature due to various environmental factors, the majority of square watermelons are artificially grown using molding techniques. These unique watermelons are typically grown inside a special square-shaped container that forces the watermelon to take on the shape of the container as it grows.

Square watermelons are primarily cultivated for their aesthetic appeal, making them perfect as decorative items, gifts, or novelty products. In Japan, square watermelons were first developed as a way to make the fruit easier to stack and store. They have since become a symbol of innovation, luxury, and a fun twist on traditional gardening.

While the square shape itself doesn’t alter the taste of the watermelon, growing a square watermelon is a fun and creative gardening project that offers a unique challenge to anyone who loves to grow interesting plants.

Why Grow a Square Watermelon?

There are several reasons why you might want to try your hand at growing square watermelons. Here are some key motivations:

1. Novelty and Fun

Growing a square watermelon is a fun and unique gardening project that sets your gardening skills apart. It’s a perfect conversation starter and can impress friends, family, and neighbors with its quirky and unexpected shape.

2. Decorative and Aesthetic Appeal

Square watermelons make beautiful and impressive decorative items, especially for events like parties or summer gatherings. They can be carved or displayed as centerpieces, and their novelty factor makes them an exciting addition to any garden or home.

3. Innovation and Challenge

If you’re passionate about gardening and enjoy trying new techniques, growing square watermelons can be a fun challenge. It involves a different approach to traditional gardening and allows you to experiment with new growing techniques that may not be commonly used.

4. Gift Idea

In Japan, square watermelons have become a luxury item and are often given as special gifts due to their unique shape. They are seen as a thoughtful, high-end gift that adds a touch of creativity and thoughtfulness. Why not try growing one as a special gift for a friend or family member?

Choosing the Right Watermelon Variety

To successfully grow square watermelons, it’s essential to start with the right variety of watermelon. While most watermelon varieties can technically be grown in a square shape using molds, certain varieties perform better for this process.

Ideal Varieties for Square Watermelons:

  • Seedless Varieties: Seedless watermelon varieties tend to grow more uniformly, which is helpful when shaping them into square form. Varieties like Crimson Sweet or Yellow Crimson are popular for their sweetness and relatively smooth shape.

  • Oblong Varieties: Some oblong watermelon varieties can be more suitable for molding into a square. Icebox watermelons, which are typically smaller, are often chosen for this purpose due to their compact size and consistent growth.

  • Large Round Varieties: For novelty purposes, you can also try growing large, round varieties like the Jubilee watermelon. However, these will require more attention to ensure uniformity in growth.

When selecting your watermelon variety, make sure to pick one that’s known for producing high-quality, healthy fruit. A watermelon that grows well in your local climate is essential for success.

Creating the Perfect Growing Conditions for Square Watermelons

Before you start shaping your square watermelons, you need to ensure that the environment is ideal for watermelon growth. Watermelons require plenty of sunlight, warmth, and space to thrive. Here's how to prepare for growing your square watermelon:

1. Soil Preparation

Watermelons grow best in loose, well-draining soil. Watermelon roots are deep and spread out, so it’s essential to prepare the soil accordingly:

  • Soil Type: Loamy soil with plenty of organic matter is ideal. If your soil is heavy in clay, amend it with compost to improve drainage.

  • Soil pH: Watermelons prefer slightly acidic soil with a pH range of 6.0 to 6.8. You can test your soil’s pH using a home test kit or by sending a sample to a local agricultural extension service.

  • Soil Fertility: Watermelons are heavy feeders, so enrich your soil with compost or well-rotted manure. Additionally, using a balanced fertilizer or one with higher potassium and phosphorus content can help your watermelon plants grow strong and produce healthy fruit.

2. Sunlight Requirements

Watermelons need full sun to thrive. Choose a planting spot that receives at least 6-8 hours of direct sunlight per day. Sunlight is essential for photosynthesis, which supports fruit growth.

3. Temperature and Climate

Watermelons are a warm-weather crop that thrives in temperatures ranging from 70°F to 90°F (21°C to 32°C) during the day. They prefer nighttime temperatures to be slightly cooler, around 60°F (15°C).

In Texas, Florida, or other warm regions, sun exposure and the natural temperature will support watermelon growth. However, if you're growing square watermelons indoors or in a cooler climate, you may need to provide additional heating through grow lights or other methods to maintain the right temperature range.

4. Watering

Watermelon plants require regular watering, especially during their early stages and fruit development. Keep the soil consistently moist, but avoid waterlogging, which can lead to root rot. Watermelon plants have deep roots, so deep watering is recommended to ensure the roots are properly hydrated.

How to Shape Your Watermelon into a Square

The key to growing a square watermelon lies in the use of molds. These molds guide the watermelon into a square shape as it grows. Here’s how to do it:

1. Choosing a Mold

You’ll need a clear, rigid mold that is large enough to accommodate the watermelon as it grows. The mold should have:

  • Good ventilation: To prevent moisture from accumulating and causing mold.

  • Transparency: This allows you to monitor the watermelon’s growth without removing the mold.

  • Sufficient size: The mold should be large enough to allow the watermelon to grow to full size while still being shaped.

Materials commonly used for molds include clear plastic or acrylic boxes, containers, or custom-built wooden frames.

2. Planting the Seedling in the Mold

Once your watermelon seedlings are ready to be transplanted, gently place them into the mold. This is typically done after the plants have reached about 4–6 inches in height. Ensure the plant is centered within the mold and has enough space to grow vertically.

3. Securing the Mold

To keep the mold secure around the growing watermelon, ensure that it fits snugly around the stem and fruit. Leave enough space for the watermelon to grow without being restricted, but also ensure that the mold is tightly closed to maintain its shape. You can use rubber bands, Velcro strips, or locking mechanisms to hold the mold in place.

4. Regular Monitoring and Adjustment

Monitor the growth of the watermelon regularly. As the fruit begins to grow, it should take on the shape of the mold. Be sure to:

  • Rotate the mold occasionally if necessary to ensure the watermelon grows evenly.

  • Adjust the mold if needed to avoid crushing the watermelon, as they can swell significantly.

Maintaining the Watermelon as It Grows

Now that your watermelon is in its mold and growing steadily, you need to care for it as it matures. Here's how to maintain a healthy, vibrant watermelon:

1. Watering and Feeding

Watermelon plants need consistent moisture, especially as they begin to fruit. Continue to water deeply and evenly, making sure the plant receives about 1 to 1.5 inches of water per week. Apply a slow-release fertilizer or organic compost around the base of the plant to promote healthy growth.

2. Pruning

To encourage the watermelon plant to focus its energy on fruit production, you should prune any excessive vines or leaves that might divert resources from the main fruit. Removing secondary shoots helps the plant direct more energy toward producing a healthy and well-shaped watermelon.

3. Pest Control

Watch for common pests like aphids, spider mites, and cucumber beetles that can infest your watermelon plants. Use organic pesticides or natural predators like ladybugs to manage pests.

Harvesting Your Square Watermelon

Once your watermelon has reached full maturity, it’s time to harvest. You’ll know it’s time to harvest your square watermelon when:

  • The melon has fully formed and grown into its square shape.

  • The skin of the watermelon turns a pale yellow, indicating ripeness.

  • The watermelon sounds hollow when tapped.

Carefully remove the watermelon from the mold, taking care not to damage the fruit. If you used a clear mold, you’ll be able to admire the unique shape before cutting into it.


Growing square watermelons is a fun and rewarding challenge that allows you to experiment with your gardening skills while producing a unique and eye-catching fruit. With the right conditions, molds, and care, you can cultivate your own square watermelon in 2025 and impress friends and family with this creative gardening feat. Whether you’re growing it for fun, as a gift, or simply to see the process through, growing square watermelons offers a new and exciting twist on traditional gardening.

Happy gardening, and enjoy the fruits of your labor!

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