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The Best Soil for Watermelon: Tips for a Juicy Harvest

If you could sum up the taste of summer in one fruit, watermelon probably comes to mind. Homegrown watermelon is the perfect treat on a hot summer day.

Do you want to grow watermelons in your garden? A great return on your efforts starts with the best soil for watermelon growth. Read on to learn how to prepare the dirt in your watermelon patch or container for growing massive, sweet fruits!

The Best Soil for Watermelons

Our Top Picks for Watermelon Soil Prep

1 – Soil Test:
MySoil Soil Test Kit

2 – Soil Texture Adjustments
Miracle-Gro Potting Mix

3 – Acidification
Espoma Soil Acidifier

4 – Fertilizer
Young Plant: Bio-tone Starter Plus Fertilizer
Blooming: Dr. Earth Flower Girl Bud and Bloom Booster

What is the Best Soil for Watermelon?

The best soil for watermelon plants should contain essential nutrients and the correct texture to promote strong roots and healthy stems and leaves. Nutrient-rich soil helps your watermelon plants grow and produce juicy watermelons with deliciously high sugar content.

Like many crops, watermelon plants prefer soil that is loose and loamy. Sandy-loam soil comprises over 50 percent sand and less than five percent clay. This mixture promotes aeration in the earth, which helps control moisture and temperature.

Air acts as insulation in sandy-loam earth, which is critical for watermelon growth. These vining plants require moist, warm soil to flourish. Watermelon plants need sunny locations as much for the soil temperature as the sunlight.

Soil Test

To achieve a suitable soil composition, you should start by analyzing the ground where you will be planting watermelon seeds with a soil test before you add any amendments.

Soil Texture

Remember your planting destination when seeking nutrient-rich, loamy garden soil for your watermelon plants. Are you planting watermelon seeds in-ground or in a raised garden bed? If that is the case, you can achieve optimal soil conditions by mixing lightweight potting soil with standard garden soil.

Start by digging a hole about one foot wide and one foot deep. If you have exceptionally hard-packed clay earth, you may want to dig a larger hole to provide more space for developing roots. Loosen and break up the native soil along the bottom and sides with a hoe or shovel.

Next, grab a bucket and combine equal parts garden soil and enriched potting soil. You might add one cup of sand to each gallon of dirt for extra drainage and soil aeration if needed. Moisten the mixture until it is damp and crumbly but not soggy. Fill your planting hole with mixed sandy-loam soil and water thoroughly.

At this stage, you can mix in some starter fertilizer and let it soak into the earth for a day or two before planting. This is especially helpful for transplanting watermelon seedlings, as it provides adequate nutrition without risking nutrient burn from direct fertilizer application. 


Melons thrive in slightly acidic conditions. The best soil for watermelon should have a pH balance between 6.0-6.8. Consider adding a soil acidifier if the planting location is particularly alkaline.


To truly create the best soil for watermelon growth, you should pay careful attention to the available nutrients. Not all dirt is the same, so again, starting with a soil test is wise to determine what needs to be added.

Quality fertilizer includes three primary nutrients: nitrogen, phosphorus, and potassium. Young plants require extra nitrogen to fuel the production of healthy stems and leaves. The best soil for watermelons at this stage should include additional nitrogen.

Growing watermelon in a garden

You must be mindful of the growth stage of your watermelon plants to ensure soil amendments are added at the proper times. Watermelon plants need different minerals throughout the growing season. You can get away with using a balanced fertilizer all year, but you will see better results if you cater to the plant’s current needs.

From a seedling’s first set of true leaves until it starts flowering is called the foliage stage. To promote strong plant development, you should amend the soil with a high-nitrogen starter fertilizer.

Should you choose organic fertilizer for your watermelon plants? Whether you purchase organic or synthetic fertilizer is up to your personal preference. Either type of fertilizer delivers the necessary nutrients for healthy watermelon plants.

Once your watermelon plant is fully mature and ready to reproduce, it reaches the flowering and fruiting stage. During this period, its nutritional needs change significantly.

When plants are gearing up to produce fruit, they do not need as much nitrogen. Instead, the fruiting and flowering process requires extra phosphorus.

To supply your watermelon with the necessary ingredients for a bountiful harvest, you’ll want to look for a fertilizer with less nitrogen and more phosphorus.

Adding Dr. Earth Flower Girl Bud and Bloom Booster to your melon patch creates the best soil composition of key minerals and helpful microbes to promote the growth of juicy watermelons.

Growing Watermelons in Containers

If you are limited on garden space, you might think you can’t grow giant, delicious watermelons. While it is true that watermelon plants can grow to enormous sizes, you can still successfully grow them in containers.

To start with, you will need a large pot around 18 inches deep and at least a foot wide (bigger is better her!). When planting outdoors, watermelons need around six feet of space between seeds. With this in mind, you should try to provide your potted watermelon with as much space as possible.

When it comes to growing in containers, picking the best soil for watermelons requires special care. Ensure you select enriched potting soil with exceptional moisture control to keep your melons hydrated and nourished all season long.


Watermelon growing

What fertilizer is best for watermelon?

Watermelon plants need different fertilizer compositions depending on their stage of growth. Young plants still putting most of their energy into foliage production need lots of extra nitrogen. Nitrogen helps plants build healthy roots, stems, vines, and leaves.

Once the plant is fully mature and ready to reproduce, its nutritional needs change. The plant will divert energy from foliage production to fruit development. 

This process is phosphorus intensive but does not rely as much on nitrogen. For this reason, specialty fertilizers are available for fruiting and flowering plants in this stage. These fertilizers provide extra phosphorus alongside a balanced ratio of nitrogen and potassium.

Do watermelons need deep soil?

If grown in the best watermelon soil, these plants can reach immense sizes when fully mature. Despite their enormity above ground, they don’t have especially deep roots.

Watermelon roots extend into the ground slightly less than a foot, creating a mound. This mound is a tangle of roots that store excess water and nutrients, providing the watermelon plant with a steady food supply.

When planting watermelons in containers, select a container at least 18 inches deep. This will provide ample space for watermelon roots to grow and develop without overcrowding. Remember that melon roots are sensitive to excess moisture, even with the best soil for growing watermelons in containers. You’ll want to ensure the container has adequate drainage to prevent root rot.

How often should watermelon be watered?

The best soil for watermelon plants is always moist without being soggy. In most circumstances, melons should get about two inches of water each week. This can vary greatly depending on temperature, airflow, and other factors.

To determine if your plants need an extra drink of water, you can do a finger test. Simply dip your finger into the earth about two inches deep. When you withdraw your finger, little crumbles of dirt should cling to your skin. This means that the soil is well-hydrated.

If your finger comes back clean, you’ll want to give your plant some water. If the mud on your finger is thick, the soil is oversaturated and needs to dry out. Even the best soil for watermelon plants can become an enemy if it’s too wet!

The Best Soil for Growing Watermelons

Creating the perfect environment for watermelon plants to thrive doesn’t need to be tricky. You can mix the best soil for watermelon growth without breaking the bank (or your back!) Once you have a loamy and warm plot, it’s time to plant your watermelon seeds and watch them grow in the best soil for growing watermelons you can make.

Want to learn more about this iconic summer fruit? Then visit our watermelon plants page to learn more about watermelon planting, growing, cooking, and more!

Shopping for your garden can get overwhelming fast. So if you’re looking for advice on tools and supplies, then you’re in the right place!