8 Best Fertilizer For Watermelon 2021 Reviews

Watermelon fertilizer. Watermelon, known botanically as Citrullus Lanatus, is a fragile and soft vegetable. It is somewhat related to the cucumber.

Watermelon is native to Africa, specifically Namibia. Watermelons are very happy with heat and humidity. The Citrullus Lanatus plant generates the biggest harvests and sweetest Watermelon fruits when placed in a full-sun exposure and are protected from cool winds.

Watermelon plants flower in the late spring months. The fruits are produced in the summer season!

To thrive well, Watermelon needs proper fertilizing and watering. Finding the best fertilizer for Watermelon can be a challenge. That is why you should discover consideration on what to choose for the best watermelon fertilizer!


  • Common Name: Watermelon
  • Scientific name: Citrullus Lanatus
  • Type: Annual
  • Family: Cucurbitaceae
  • Native Range: Namibia
  • USDA hardiness zone: 2 to 11
  • Height: between 0.75 to 1.50 feet
  • Spread: between 10 to 15 feet
  • Bloom Time: July to August
  • Bloom Description: Pale green
  • Ligh requirement: Full sun
  • Watering requirement: Medium
  • Maintenance: Medium
  • Usage: Annual, Vegetable
  • Flower: Showy
  • Fruit: Showy, Edible

What is the best watermelon fertilizer?

The best watermelon fertilizer is best determined by a soil test. But if you do not have a soil test, it would be best to apply 20-10-20 NPK formulation at the rate of 15 pounds per 500 feet. Or you can apply fertilizer for vegetables and fruits.

To prevent Nitrogen burn, blend the fertilizer with the top six inches of soil. Compost helps in enhancing the soil structure, adds micronutrients in the mix, and helps in water retention.

You can also add mulch around the Watermelon plants to improve moisture retention, prevent weed growth and add Nitrogen-rich organic matter to the soil.

When feeding Watermelons with granular food, do not let it contact with the leaves. The leaves are sensitive, and you could harm them.

To absorb the nutrient to the root, water well. An application of fertilizer that has a higher amount of Phosphorous and Potassium can be used while the fruit is maturing.


List of the best Watermelon fertilizer reviews

1. JR Peters Fertilizer Jack’s Classic 12-15-30 Watermelon Fertilizer

Best Fertilizer For Watermelon

JR Peters Fertilizer Jack’s Classic Watermelon Fertilizer is explicitly formulated for the Tomato plant. However, this JR Peters Fertilizer water-soluble plant food filled with micronutrients for tomatoes and all fruiting vine vegetables, including Watermelons.

The Watermelon fertilizer has to be mixed with water for the most accurate and useful nutrients provided to your plants. This JR Peters Fertilizer is a great combination of nutrients supplies the nutrients needed most by Watermelon.

The Potassium level in the JR Peters Fertilizer is higher than other elements to make sure a good crop with enhanced micronutrient levels that produce more fruit, vibrant green leaves, and healthy vines.

Other roles of Potassium for Watermelon plants are:

  • Enhancing Watermelon plant’s water use through regulation of transpiration and photosynthesis
  • Improving Nitrogen use
  • Improving protein production
  • Boosting plant health
  • Improving the ability to withstand drought, pests, and disease.

When mixing with water, you can use the free measuring spoon for the accurate product application. You must follow the instruction provided in each container.


2. Old Farmer’s Almanac 2.25 lb. Organic Plant Food Fertilizer For Watermelon 8-4-8

Best Fertilizer For Watermelon

This Old Farmer’s Almanac Plant Food is an OMRI-Listed fertilizer for Watermelon, tomatoes, vegetables, other fruit, herbs, trees, and shrubs. When applied to the soil, Old Farmer’s Almanac Plant Food works with the ecosystem to encourage healthy Watermelon plant growth.

This Old Farmer’s Almanac fertilizer is suitable for outdoor and indoor organic gardens. The ingredients are derived from feather meal, Soybean, blood meal, bone meal, and sulfate of potash. So it is an organic fertilizer and a great organic choice for Watermelon fertilizer.

When you are starting to plant your Watermelon plants, you can spread the Old Farmer’s Almanac Plant Food evenly over excavated soil. Mix 2.5 cups per 100 square meter with soil in five to eight inches depth while planting the Watermelon plant.

On an established Watermelon plant, apply 2.5 cups per 100 square meter at the beginning of the growing season. Apply six to eight weeks after the application. Spread evenly over the growing area.

You can apply the Old Farmer’s Almanac Plant Food the same practice on a potted established Watermelon plant.


3. EcoScraps for Organic Gardening Tomato & Vegetable Plant Food

Best Fertilizer For Watermelon

Ecoscraps for Organic Gardening Tomato and Vegetable Plant Food consists of a combination of ingredients. These include Total Nitrogen (N) (5.0%), Water Insoluble Nitrogen (5.0%), Available Phosphate (P2o5) (4.0%), Soluble Potash (K2o) (6.0%), and Calcium (Ca) (1.0%).

These ingredients are derived from compost, bone meal, blood meal, Sulfate of Potash, and Calcitic Lime.

Add one to two inches and combining the top five to six inches of soil for new Watermelon garden beds. On sow seed, blend the top four inches of soil at the rate of four lbs per 100 square feet set—water well.

Provide established Watermelons (Citrullus Lanatus) plants every four to six weeks through the growing season. Use one pound for every fifty square feet of garden area on each plant. Mix the EcoScraps fertilizer into the soil surface and water well. 

For Watermelons in containers, feed Watermelon plants one tablespoon for every six inches of pot diameter. Mix into the soil, and water thoroughly.

Apply this fertilizer every month. Here are the benefits of EcoScraps fertilizer:

  • Can provide good nutrients to all types of vegetables
  • Clean, even, and easy application
  • Make less landfill waste
  • No poop

4. Jobe’s Organics Organic All Purpose Granular Fertilizer 4-4-4

This Jobe’s Organics fertilizer consists of 4-4-4 NPK formulation derived from feather meal, sulfate of potash, and bone meal. There is also added Calcium, Magnesium, and Sulfur. It is an organic fertilizer.

The Jobe’s Organics fertilizer comes in the form of granular, and works fast as Watermelon fertilizer and flowers, vegetables, shrubs, trees, and plants. Other than the organic material, this Jobe’s Organics fertilizer comes with Jobe’s Biozome. Its is a proprietary microorganism Archaea that breaks down material for faster results.

This Biozome enhances soil conditions. The Jobe’s Organics fertilizer can help Watermelon plants withstand disease, can help resist insects, and can help survive the drought during its growing season.


5. Burpee Tomato Fertilizer Vegetable Organic Granular Plant Food

Burpee Tomato Fertilizer granular plant food is embellished with the much-needed nutrients. These nutrients help enhance robust root development and beneficial microorganisms for vegetables and fruits including Watermelon.

What you will expect from the Burpee Tomato Fertilizer are improved soil and better healthy Watermelon plant growth. These nutrients are immediately released and continuously provide a stream of plant food for up to three months.

With this beneficial form, the Watermelon plant vigorously has green foliage all season long and fruit at harvest time. You can apply the Burpee Tomato Fertilizer for seed starting, mature Watermelon plant, young bedding plants, and patio container Watermelon plants. It is an excellent choice of fertilizer for Watermelon.


6. Miracle-Gro Shake And Feed Tomato, Fruit & Vegetable Plant Food

This Miracle Gro Shake And Feed is an excellent choice if you want to apply it to your Watermelon plants. The Miracle Gro Shake And Feed is all-purpose plant food for fruits and vegetables.

The fertilizer is particularly formulated for helping Watermelon plants grow more productive, grow stronger, and vibrant. This Miracle-Gro Shake And Feed fertilizer provides many important nutrients that help nourish and feed Watermelon plants above and below the soil.

It comes in granular form. Its microbes break down and transform natural ingredients into nutrients.

These nutrients support root development and strength which improves water efficiency. The Miracle Gro Shake And Feed can feed the Watermelon plants for 3 months.

The Miracle Gro Shake And Feed contains natural ingredients including kelp, earthworm casting, bone meal, and feather meal.


7. Miracle-Gro Performance Organics For Fruits, Vegetables, And Herbs

This Miracle Gro Performance Organics fertilizer can feed your outdoor and indoor container plants such as Watermelon for up to ninety days. The Miracle Gro Performance Organics is OMRI that contains aged compost blend with other natural and organic ingredients.

The NPK formulation is 9-4-12 which can cover up to 265 square feet area from one container. All you have to do is to feed the plant with the Miracle Gro Performance Organics fertilizer every seven days and soak the soil to get nutrition down to the roots.


8. Lily Miller Fertilizer All Purpose Planting And Growing Food

This Lilly Miller fertilizer has a balanced NPK formulation of 10-10-10. The Lily Miller fertilizer is blended from natural ingredients with other traditional plant foods.

This mix will produce a fertilizer that provides nitrogen from four various sources. The mix of nutrients will be available to plants fast for a great start.

The combination of nutrients also can feed your Watermelons for up to six weeks. The Lilly Miller fertilizer is fortified with important plant minerals.

The right combination of nutrients is slow-release to grow lush foliage, steady growth, colorful blooms, productive fruits, and delicious vegetables.


Watermelon fertilizer ratio

To grow Watermelon you need to know that the plant needs micronutrients and macronutrients. NPK is the key macronutrients for Watermelon. Check fertilizer labels to discover the NPK formulation ratio.

The best Watermelon fertilizer ratio is higher nitrogen fertilizer when they are in the early stage of growth. Watermelon plants need fertilizer that has more potassium and phosphorus for its production.

If you apply high nitrogen fertilizers after the melons are developing, the foliage may grow excessively rather than melon development!

Once you are ready to transplant or the seedlings have emerged, it would be better to top dress with an NPK formulation ratio of roughly 1-1-1. You can apply either 5-5-5- or 10-10-10 general all-purpose fertilizer.

Fertilize the watermelon plants with 680 grams per 9 square meter of garden space. Never touch the leaves with granular food when fertilizing. The Watermelon leaves are sensitive and could be damaged.

Soak the soil with water so the roots can easily absorb the nutrients.

The Watermelon fertilizer ratio of 1-1-1 such as 10-10-10 or 14-14-14 NPK formulation can be applied throughout the lifecycle of the plant. Keep in mind switching from higher nitrogen to a more balanced ratio when your melon set.

Apply fertilization one time before the first planting of the seed or when transplanting the seedling. Fertilize one time when the vines start to ramble. And one time when the watermelons are set.


How long does it take to grow a Watermelon?

On average, Watermelon plants reach harvest between seventy to eighty-five days after sowing. Smaller varieties will usually be ready before larger varieties.


How to pick a ripe Watermelon?

As Watermelons near maturity, the vine’s tendrils start to die and turn brown. Some Watermelon varieties are having a circular crack around the stem.

Other varieties soften at the blossom end. If you notice one side of the fruit was resting on the ground, the fruit will go from white to yellow.

When you thump the melon and produce a dull sound, this means that it is a ripe Watermelon.

If you notice little contrast between the stripes, the watermelon is ripe.

Immature Watermelons have a white bottom while ripe Watermelons will have a cream- or yellow-colored bottom.

See if the tendril is green, it is not ripe. If the tendril is like half-dead, it is almost ripe. If the tendril is dead, it is a ripe Watermelon!


Where to plant watermelon?

Before planting Watermelon, you should prepare the planting site. You can prepare the site by amending the soil with aged manure, seaweed, and compost.

Watermelons like to live in loamy, sandy, and well-drained soil. You should check that the soil pH is between 6.0 and 7.0 or slightly acidic.

If you are growing the vines in raised rows, make sure good drainage and withstand the sun’s heat longer. Space the plants about two feet apart. If you are growing in rows, space six feet by six feet apart.

The area must have a lot of space because the vines can grow up to fifteen to twenty inches long.

You must prevent weeds from growing. You can add mulch to prevent weeds.


When is the best time to fertilize Watermelon?

According to many resources, there is no specific timeline on when to fertilize Watermelon. You can start feeding the plant determined by the most recent soil condition and by the stage of growth of the Watermelon plant.

A new seedling Watermelon has different nutritional needs. While in the stage of bloom, the Watermelon fertilizer requirements are different too.

For starter, use nitrogen-based fertilizer to fulfill Watermelon fertilizer requirements. When you see the Watermelon plant starts flowering, feed the Watermelon with Phosphorus and Potassium-based fertilizer.

Citrullus Lanatus plant requires rich both fertilizer for optimal fruit production.


How often to fertilize Watermelon?

Feed the watermelon plant one time every week, preferably with a liquid soluble fertilizer. Apply a 20-10-20 NPK formulation of compost until the flowers of the plant bloom. When you notice the flower bloom, use a 20-20-20 fertilizer for the rest of the growing season.


What is the best environment for Watermelon?

To plant Watermelon seed, you need fertile and well-tilled soil. Generate soil amendments with compost and manure to raise the nutrient level in the ground.

You can add sharp sand for proper drainage. You may consider applying a slow-release fertilizer into the soil. This practice will add a continuous boost of nutrients and better choice for Watermelon plants.

Slow-release fertilizer reduces your maintenance and labour during the growing season. Add food plant right before planting these seeds.

Place your Watermelon in a site with full-sun exposure. The best location would be a warm and humid micro-climate.

Place the plant in the south-facing wall of a house. The young plants and seeds will require a minimum of one inch of water per week to keep the soil uniformly moist.


How to grow Watermelon?

Watermelon seeds need to be located outdoors in the spring or best if the soil is warmer than 70 degrees Fahrenheit for better germintaion. These seeds can be placed up to twenty days indoors before planting in the garden.

Never start sooner because large watermelon seedlings do not transplant well.

This practice will provide you with a jump on the growing season. Give your indoor seedlings with warm temperatures between 80 and 85 degrees Fahrenheit, moist soil, and bright light.

For outdoor seed sowing, bury seeds one inch deep into the soil. Keep six feet apart between each seed. Cover these seeds with displaced soil and water well.

Maintain moist soil around the seeds during germination and sprouting. Watermelon flowers will bloom about forty-five days after blooming. This would be the time for harvesting.


The types of Watermelons to grow

Watermelons are a delicious fruit that is sweet and refreshing. Watermelons are perfect to be enjoyed ice cold when the weather is warm.

Watermelon plants require four months of warm weather to thrive well. They can be grown in most USDA hardiness zones.

There are times when Watermelon plants produce less fruit which is worth considering if you want to grow watermelons during cool weather. Here ae the list od Watermelon types to grow.

1. Black Diamond Watermelon

Black Diamond Watermelon

The Black Diamond Watermelon plants or Citrullus Lanatus ‘Black Diamond’ can produce large mature size watermelons that can exceed 50 pounds in weight. The rinds of the Black Diamond Watermelons are tough and hard.

The fruit inside is juicy flesh and firm. These Black Diamond Watermelons grow on vines that can be trained to crawl on a structure or scramble across the soil.

The Black Diamond Watermelons require much space to produce large fruits. The plants need ninety days to reach maturity.

To thrive well, these plants require a minimum of six hours of sun each day. The soil must be well-drained and you should water the Black Diamond Watermelon plant when the soil is dry.


2. Charleston Gray Watermelon

Charleston Gray Watermelon plants or Citrullus Lanatus ‘Charleston Gray’ are very popular among home gardeners. The Charleston Gray Watermelons are grown by commercial growers for more than forty years.

The size of Charleston Gray Watermelons is enormous, stretched melons, and the name comes from its greenish-gray rind. The melon is a bright red flesh with a juicy and sweet taste.

All you have to do to grow Charleston Gray Watermelon is by providing plenty of sunlight. It is consider one of the best American watermelons ever produced.

To get to its maturity stage, it would take eighty seven days. The Charleston Gray Watermelon can to weights of between twenty and forty pounds.


3. Crimson Sweet Watermelon

This Crimson Sweet Watermelon is one of the best tastings melons that have disease-resistant features. The disease-resistant features make growing Crimson Sweet Watermelons much easier.

If you are a beginner, this is the type of watermelon to choose. The sweetness of the fruit is what you want to achieve at the end of the season.

It is one of the many benefits if you are growing Crimson Sweet Watermelon in your garden.

To reach its maturity stage, Crimson Sweet Watermelon takes between eighty to eighty-five days. It is time to harvest watermelons.

The Crimson Sweet Watermelon is commercially very popular because it is easier to sell due to its firm and sweet flesh. It can be stored and shipped well after the harvest season.

You can keep the Crimson Sweet Watermelon for three weeks in cool conditions or outside of a refrigerator. The weight could reach between sixteen and twenty-six pounds.

The shape is oval with the combination of pale green and dark green striped skin. You can start from seed sown outdoors at a constant temperature above 65ºF.

Be careful to sown outdoors during winter or cooler areas, where you have to sow the seeds indoors four weeks earlier. After that you can transplant outdoors when the weather gets warmer.

You can plant the Crimson Sweet Watermelon easily with much moisture, well-draining soil, and full sun.

Frequently ask question

Why do the Watermelon leaves turn to yellow?

Overwatering can cause yellowing of the leaves as it can make it harder for the Watermelon plant to absorb nutrients. Overwatering can wash the nitrogen out of the soil. Before you water, make sure to stick your finger about an inch into the soil to see if the soil is moist. If it is still moist, do not water the Watermelons.


Why are the Watermelon plants dying?

If you notice your Watermelons are wilting, this is the sign that there is a fungal problem. The fungal comes from the soil. Fusarium wilt of Watermelons causes plants to wilt. Pull out a Watermelon plant and find any discolouration at the base or on the roots. Use a fungicide to fix the problem.


How to increase the yield of the Watermelon plant?

You can maximize the size of the Watermelon fruits by watering the plants at the base in regular which keeps the soil moist. Apply a fertilizer designed for edible crops or compost tea fertilizer to feed. The fertilizer stimulates growth to get larger melons.


How many Watermelon fruits do you get per plant?

Healthy watermelon vines can produce two to four fruits per plant. The vines produce female and male flowers.


What is the best month to plant watermelon?

Watermelon seeds should be planted outdoors after all threats of frost have passed or in the Spring months. Seeds should be placed indoors up to twenty days before planting in the garden.


8 Best Fertilizer For Watermelon 2021 Reviews
Scroll to top