Watermelon Square Foot Gardening: How to Grow

Watermelons are a delightful summer treat, but their sprawling vines can take up a lot of garden space. The good news is that you can still grow your own watermelon even if you have limited space, thanks to square foot gardening.

This efficient method maximizes your yield per square foot. Let’s take a look at how you can grow watermelon using the square foot gardening method.

Also, Read: Square Foot Gardening Pumpkins

Understanding Square Foot Gardening

Square foot gardening is a method popularized by Mel Bartholomew in the 1980s. It involves dividing a growing area into small square sections, typically 1×1 foot each. This method aims to produce a diverse, high-yield crop in a limited space.

Choosing the Right Watermelon Variety

Not all watermelon varieties are suitable for square foot gardening, as some can take up a lot of space. Choose bush or compact varieties that are bred for small spaces. Some good options include ‘Sugar Baby,’ ‘Bush Sugar Baby,’ and ‘Golden Midget.’

Preparing Your Square Foot Garden

Follow the below points to prepare Your Square Foot Garden:

Selecting the Location

  • Firstly, find a sunny location for your square foot garden. Watermelon plants need at least 6 hours of direct sunlight each day to grow well. The location should also have good drainage to prevent water from pooling, which can lead to root rot.

Building the Frame

  • A square foot garden typically consists of a 4×4 foot raised bed. This size makes it easy to reach into the center from any side.
  • You can construct the frame from non-treated wood, such as cedar, or any other non-toxic material that won’t degrade quickly outdoors. You can also purchase pre-made square foot gardening kits.

Creating the Grid

  • A key aspect of square foot gardening is the grid, which separates the growing area into individual squares, each one foot across.
  • You can make your grid from thin strips of wood, thick string, or plastic. The grid helps with organization, ensuring each plant has its own space.

Preparing the Soil

  • Once your frame and grid are ready, it’s time to prepare the soil. The soil in your square foot garden should be rich in nutrients, well-draining, and easy to work with. Mel Bartholomew, the creator of the square foot gardening method, recommends a soil blend called ‘Mel’s Mix.’
  • This consists of 1/3 compost (from various sources), 1/3 peat moss (or coco coir), and 1/3 vermiculite.
  • The compost provides a wide range of nutrients for your plants. If you can get a blend of different composts, even better, as each type brings different nutrients to the mix.
  • The peat moss or coco coir contributes to the soil’s water retention capacity, keeping moisture in the soil for the plants to access. Vermiculite further aids in maintaining moisture and provides the soil mix with aeration, which encourages root growth.
  • Fill your frame with this mix to create a nutrient-rich, well-draining environment for your watermelon plants.

Planning Your Planting

  • Plan your planting to ensure each plant has the space it needs. Watermelons require a lot of space to grow, so you’ll be planting one watermelon plant per square.
  • By properly preparing your square foot garden, you set the foundation for a productive and space-efficient growing season. You’ll be amazed at what you can achieve in such a compact space.

Check out: Chamomile Square Foot Gardening

Planting Your Watermelon Seeds

In each square, plant 2-3 watermelon seeds about 1 inch deep. Once the seedlings emerge, thin them out, leaving the strongest seedling in each square.

Caring for Your Watermelon Plants

Follow the below instructions to care for your watermelon plants:


  • Watermelon plants thrive under full sun, requiring a minimum of six hours of direct sunlight per day. A location that offers even more sunlight would be better, but ensure that during the hottest part of the day, the plants are not being scorched.
  • If your plants show signs of scorching, consider providing some shade during the peak heat hours.


  • Watermelons, true to their name, have a high water requirement. Consistent watering is crucial for growing juicy and healthy watermelons.
  • However, water judiciously to avoid overwatering, which could lead to waterlogging and subsequent root rot. The soil should be kept moist, but not waterlogged.
  • Water your plants deeply and infrequently as opposed to little and often. This technique encourages the growth of deep roots which helps the plant become more drought-resistant.
  • Also, it is better to water early in the morning, as watering later in the day can lead to water evaporation and overnight watering can contribute to mold growth.


  • Watermelon plants are heavy feeders, so they will benefit from regular feedings. Use a balanced, slow-release fertilizer (like a 10-10-10 NPK fertilizer). Follow the manufacturer’s instructions for application rates and frequencies.
  • Generally, you should fertilize at the time of planting, then again when the plant begins to vine, and finally when the fruits start to develop.

Pest and Disease Control

  • Monitor your plants for common pests like aphids, cucumber beetles, and squash bugs. Handpicking can control small infestations. For larger pest issues, consider organic pesticides or insecticidal soaps.
  • Common diseases include powdery mildew, downy mildew, and various types of wilt. Many of these can be controlled with proper plant spacing for good air circulation, watering at the soil level rather than from overhead, and applying organic fungicides if necessary.

Training the Vines

  • In a square foot garden, space is at a premium, so it’s helpful to train your watermelon vines to grow vertically. You can do this by providing a strong trellis and gently guiding the vines up this structure.
  • As the watermelons begin to grow, they will need support to keep them from breaking off the vine. You can use slings made from old t-shirts or pantyhose to support the growing fruits.
  • Proper care of your watermelon plants can greatly enhance the yield and quality of your harvest. By meeting the specific needs of your watermelons, you set the stage for a successful growing season.

Have a look: Square Foot Gardening Sugar Snap Peas

Harvesting Your Watermelons

Knowing when to harvest can be a bit tricky with watermelons. Generally, watermelons are ready to harvest when the spot where the fruit rests on the ground turns from white to a rich yellow color. The tendrils nearest to the fruit will also dry out.

Checking the Tendril and Leaf

  • One commonly used method to determine if a watermelon is ripe is by checking the tendril (a spiraling stem) closest to the fruit. When the tendril turns brown and dries up, the watermelon is typically ready for harvest.
  • Along with the tendril, you can also look at the leaf nearest to it. If both the leaf and the tendril are dried up, the fruit is likely ready.

Assessing the Field Spot

  • The field spot is the part of the watermelon that was resting on the ground. As the watermelon matures, this spot transitions from white to a creamy yellow or light orange color. If the field spot is still white or green, the fruit is probably not ripe yet.

Tap Test or Thump Method

  • Many gardeners also rely on the ‘tap test’ or ‘thump method’ to check the ripeness of watermelons.
  • When you tap or thump on the skin of the fruit, a ripe watermelon will produce a deep, hollow sound. An unripe fruit will give a higher-pitched and somewhat metallic sound. This method takes a little practice to get familiar with the sounds.

Size and Color

  • Depending on the variety of watermelon, the size and color can also be indicative of ripeness. When the fruit has reached its expected size and the outer color is rich and uniform (except for the field spot), it is likely ready to be harvested.

Harvesting the Fruit

  • Once you’ve determined that your watermelon is ripe, it’s time to harvest. Use a sharp knife or pruning shears to cut the fruit from the vine. Make sure to leave a couple of inches of stem on the fruit to help it stay fresh longer.
  • It’s important to handle the harvested watermelons with care as they can bruise or split open, leading to quicker spoilage. After harvesting, you can store your watermelons in a cool place for up to a couple of weeks.


1. Can I grow watermelon vertically in a square foot garden?

Yes. To save space, you can train the vines to grow vertically up a sturdy trellis. Just make sure to provide support for the growing fruits to prevent them from falling off.

2. How much water does my watermelon plant need?

Watermelon plants need consistent moisture, but the soil should never be waterlogged. A good rule of thumb is to water deeply once a week, or more often during dry spells.

3. What other plants can I grow in my square foot garden?

You can grow a variety of vegetables in your square foot garden. Good companions for watermelon include corn, nasturtiums, and radishes.

4. Why are my watermelon leaves turning yellow?

Yellow leaves can be a sign of several issues, including overwatering, nutrient deficiencies, or disease.

5. How many watermelons will I get per plant?

The number of fruits per plant can vary depending on the variety and growing conditions, but most compact varieties produce 2-3 fruits per plant.

Watermelon square foot gardening
Watermelon square foot gardening

Additionally, you may like some more square foot gardening tutorials:


Growing watermelon in a square foot garden can be a fun and fruitful endeavor. With the right care and attention, you’ll be able to enjoy the fruits of your labor – sweet and juicy watermelons that you’ve grown right in your own backyard or patio.

Not only does square foot gardening save space, but it also allows for a more efficient use of water and nutrients.

So, even with limited space, you can enjoy gardening and the delightful experience of growing your own watermelon. Start planning your square foot garden today and look forward to the rewarding harvest of watermelons in the near future. Happy gardening!