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Published Apr. 6, 2022

The best tomato fertilizers are a necessary addition to your garden if you hope to grow sweet, juicy tomatoes. This is because the soil in your yard will rarely contain the appropriate balance of nutrients required to grow strong, healthy tomato plants. This isn’t to say that you can’t grow tomatoes in your garden without fertilizer, just that the yield will be significantly better when you use a fertilizer according to the needs of your garden’s soil.

Keep in mind that to produce a healthy yield of tomatoes, it’s important to have a basic understanding of the life cycle of the plants, as well as knowledge of what nutrients are necessary for improving growth and taste during the various life stages. Here are our top picks, along with more information to help you choose the best tomato fertilizers for your garden.

How We Picked the Best Tomato Fertilizers

Due to the wide variety of tomato fertilizer products available on the market, we researched more than 40 different options in order to find the top tomato fertilizers for indoor and outdoor gardens. Several years of gardening experience helped form the foundation for research into the various products, with a specific focus on the chemical composition of each tomato fertilizer.

The type of fertilizer was also an important consideration, as some forms of fertilizer are much easier to use, making them ideal for beginners who are just jumping into home gardening. Other fertilizer types are better for precise control, giving experienced growers the ability to improve their yields through carefully planned and measured application. 

We also took price and product quantity into account during the research process, though these factors only really affected the outcome when two products were similar in quality. In these instances, when all things were essentially equal, the product with the better price provided more value to the consumer.

Best Tomato Fertilizers: Reviews and Recommendations

Best Overall: Dr. Earth Home Grown Tomato, Vegetable & Herb Fertilizer

Dr. Earth

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Why It Made the Cut: The balanced nutrient composition and non-GMO formula make this tomato fertilizer ideal for DIY growers.

Specs:

  • Type: Granular
  • Composition: NPK 4-6-3
  • Quantity: 4 pounds

Pros:

  • Non-GMO Project-verified fertilizer
  • Organic, people- and pet-safe formula
  • Suitable for a wide variety of plants
  • Calcium supplement aids plant growth

Cons:

  • Strong odor, store outside in a shed or garage

Improve the health and yield of homegrown tomato plants with the easy-to-use Dr. Earth Home Grown Tomato, Vegetable & Herb Fertilizer. This granular fertilizer is composed of fishbone meal, bone meal, feather meal, alfalfa meal, potassium sulfate, fish meal, kelp meal, rock phosphate, and kelp flour with 4 percent nitrogen, 6 percent phosphate, 3 percent potassium, and 7.5 percent calcium. This formulation encourages plant growth while warding off disease. 

The tomato fertilizer boasts a non-GMO, organic formula, so beginners and experienced DIY growers can feel confident feeding their tomatoes to friends and family. Apply the fertilizer evenly over the soil or mix it into the soil for new plantings. Suggested measurements are provided on the back of the package to help prevent over-fertilizing. This product is available in 1-pound, 4-pound, and 12-pound bags, though it should be noted that it gives off a strong odor, so we recommend you store the fertilizer outdoors in a shed or garage. 

Best Value: Jobe’s Tomato Fertilizer Spikes

Jobe’s

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Why It Made the Cut: This slow-release granular fertilizer is tightly packed into pre-measured spikes to help prevent wasteful runoff.

Specs:

  • Type: Granular
  • Composition: NPK 6-18-6
  • Quantity: 3.9 ounces or 18 fertilizer spikes

Pros:

  • Simple, effective application
  • Pre-measured fertilizer spikes help prevent over-fertilization
  • High level of phosphate is ideal for fruit development

Cons:

  • Small package
  • Fertilizer spikes may be broken

Affordable and easy to use, this 18-pack of Jobe’s Tomato Fertilizer Spikes is designed to make gardening simple, even for beginners. The directions on the package clearly indicate the number of spikes to use per tomato plant and how to insert the spikes into the soil for the best results. Each spike is made up of pre-measured fertilizer with a 6-18-6 NPK formula. The fertilizer is derived from ureaform, ammonium phosphate, triple superphosphate, potassium sulfate, and less than 0.2 percent chlorine. 

While the simple application method is a highlight of these slow-release granular fertilizer spikes, it’s also important to note that this form of fertilizer reduces the amount of runoff from rain or watering. The fertilizer spikes are especially useful during the fruit development stage due to the high level of phosphate. Just keep in mind that while the package comes with 18 spikes, it’s still a relatively small quantity at just 3.9 ounces. Additionally, the pre-measured fertilizer spikes may be broken inside the package, so be prepared for some loose fertilizer at the bottom of the bag. 

Best Water-Soluble: Ludicrous Nutrients Big A** Tomatoes Fertilizer

Ludicrous Nutrients

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Why It Made the Cut: Save storage space without sacrificing quantity with this 1.5-pound, water-soluble fertilizer that can make up to 1.3 gallons of liquid fertilizer.

Specs:

  • Type: Water-Soluble
  • Composition: NPK 9-1.5-7
  • Quantity: 1.5 pounds

Pros:

  • Saves storage space in the shed or garage
  • Contains several beneficial micronutrients
  • Can be applied to plants throughout the growth cycle
  • Organic, eco-friendly formula

Cons:

  • Must mix to use

Ludicrous Nutrients Big A** Tomatoes Fertilizer is a water-soluble option that is intended to be used throughout the entire growth cycle. The package weighs just 1.5 pounds, so it may not seem like enough fertilizer for the price, but users can mix this fertilizer with water to create up to 1.3 gallons of liquid fertilizer. The NPK ratio is 9 percent nitrogen, 1.5 percent phosphorus, and 7 percent potassium. If the fertilizer was only composed of these major nutrients, then it would be suitable for the early growth stage of the plant and less suitable for the later stages. However, the fertilizer formula also includes a wide variety of micronutrients that help to supplement the growth of the tomato plants.

The tomato fertilizer contains 4.5 percent calcium, 1 percent magnesium, 0.32 percent manganese, 0.35 percent zinc, 0.0875 percent boron, 0.125 percent copper, and 0.2 percent iron. Just keep in mind that you will need to mix the fertilizer, following the directions on the back of the package, before it can be used. 

Best Granular: Jobe’s 09026NA Plant Food Vegetables & Tomato

Jobe’s

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Why It Made the Cut: This fertilizer has a straightforward balance of the major nutrients to boost new plant growth and help support fruit production.

Specs:

  • Type: Granular
  • Composition: NPK 2-5-3
  • Quantity: 4 pounds

Pros:

  • Balanced composition is essential for new plants
  • Organic, eco-friendly formula
  • Suitable for a wide variety of plants
  • Contains several beneficial micronutrients

Cons:

  • Rain and watering can cause runoff

Jobe’s Plant Food Vegetables & Tomato Fertilizer comes in a 4-pound bag with an easy-pour design for improved application accuracy. The granular fertilizer can be mixed into the soil before planting, added to the soil during early plant growth, or applied at the base of established tomato plants to improve fruit yield. Make sure to follow the directions on the package to ensure you use the right amount of tomato fertilizer in your garden. 

This product contains 2 percent nitrogen, 5 percent phosphorus, 3 percent potassium, 7 percent calcium, 0.5 percent magnesium, and 1.4 percent sulfur to help improve plant growth and prevent disease. Just keep in mind that granular fertilizer products are simple to apply, but during rain or watering, loose fertilizer on the top of the soil can be carried away by the flow of running water. This runoff reduces the effectiveness of the fertilizer in the garden and may contribute to ongoing water contamination problems. Runoff can be reduced by mixing the fertilizer into the soil instead of simply pouring it on top of the soil. 

Best Liquid: Fox Farm Grow Big Liquid Concentrate

Twin Canaries Liquid Volume Conversion Chart

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Why It Made the Cut: Make up to 96 gallons of liquid fertilizer with this impressive product following the manufacturer’s recommended ratio of about 1 to 3 teaspoons per gallon of water.

Specs:

  • Type: Liquid
  • Composition: NPK 6-4-4
  • Quantity: 1 pound

Pros:

  • Easy to store
  • Manufacturer-provided soil feeding schedule
  • Optimal for early growth
  • Makes 32 to 96 gallons of liquid fertilizer

Cons:

  • Must mix to use
  • Not suitable for fruit formation

Sometimes the hardest part of gardening is getting the small plants to grow large enough to start producing fruit. This is especially true for outdoor gardens that are prone to weeds, because the weeds choke out the new plants. However, using a fast-acting fertilizer that’s designed specifically to enhance the early growth stage of the plant, like Fox Farm Grow Big Liquid Fertilizer, allows new tomato plants to get the nutrients they need to sprout up strong and healthy. The Fox Farm fertilizer contains 6 percent nitrogen, 4 percent phosphorus, and 4 percent potassium to help ensure healthy stalk and leaf growth.

The drawback to using a specialized formula, instead of a fertilizer intended for the entire growth cycle, is that it isn’t suitable for the later growth stages. Switch to a high phosphorus and high potassium fertilizer to improve fruit production. Mix 1 to 3 teaspoons of this liquid concentrate with 1 gallon of water and apply the solution on a weekly schedule. The 1-pound package can make between 32 to 96 gallons of liquid fertilizer by following the recommended ratio. 

Things to Consider Before Buying Tomato Fertilizer

If you want your garden to flourish, then it’s important to be knowledgeable about what you are applying to the soil or feeding to the plants. These nutrients can help your tomato plants grow strong and healthy, so you can enjoy fresh, delicious tomatoes straight from your garden. 

Type and Application

You can find several different types of tomato fertilizers based on how the fertilizer is applied. These types include granular, liquid, and water-soluble options, with some variations in each category. 

  • Granular fertilizer is one of the most common options; it’s incorporated into the soil before planting the tomatoes, or spread over the top of the soil at the base of the plant so that the nutrients can be absorbed by the root system. This type of fertilizer is available in both quick-release and slow-release formulas, giving DIY growers the option of a slow, steady release of nutrients into the soil or a quick burst to rapidly improve the health of the plants. 
  • Liquid fertilizer is a concentrate that must be mixed with water before it can be applied to the soil or to the plants. Follow the manufacturer’s directions to find the ratio of water to liquid fertilizer, then mix the amount you need before applying it to the garden.
  • Water-soluble fertilizer, as the name suggests, comes in a micro-granular or powdered form that dissolves in water. Mix the fertilizer according to the manufacturer’s directions, then apply the solution to the soil. These products have a similar application method to liquid fertilizers, but they can last longer in a storage shed or garage without expiring.

Chemical Composition

The entire purpose of tomato fertilizer is to add nutrients to soil that lacks them. This provides the nutrition necessary for the tomato plants to grow healthy and strong. Tomato fertilizers typically note the concentration of major nutrients on the package, including nitrogen (N), phosphorus (P), and potassium (K), making it easy for DIY growers to select the right product. 

  • Nitrogen is a major nutrient that is necessary for healthy stalk and leaf growth because it’s a primary component in the production of chlorophyll. Make sure your plants have enough nitrogen, especially during the early growth, vegetative, and flowering stages. Levels of nitrogen can be lowered during the fruit formation and mature fruiting stages. 
  • Phosphorus is the second major nutrient indicated by the familiar NPK ratio displayed on most tomato fertilizer packages. It helps the plant produce proteins, ward off pests, and even prevent disease, so it’s important to have a balanced amount of phosphorus throughout the growth cycle, with a higher concentration during the fruit formation and mature fruiting stages.
  • Potassium makes up the third part of the ratio of major nutrients, along with nitrogen and phosphorus. Tomato plants use potassium to regulate carbon dioxide intake and to help facilitate photosynthesis. Apply potassium in balanced concentrations with the other two major nutrients during the early growth, vegetative, and flowering stages. Increase the amount of potassium during the fruit formation and mature fruiting stages to help promote healthy growth.

Growth Cycle

While you may be able to grow some tomatoes by simply burying a few seeds in an unprepared garden, it isn’t likely to result in the best tasting fruit. To really enjoy the food you grow in your garden, it’s a good idea to have a basic understanding of a tomato plant’s growth cycle and what nutrients it needs at each stage.

The early growth stage is in the first 25 to 30 days, when the plant just begins to sprout. During this time it’s necessary to have a balanced concentration of nitrogen, phosphorus, and potassium in order to promote strong, healthy plant growth. Continue to apply this balanced formula during the vegetative stage of the plant, which typically lasts for about 20 to 25 days. 

The middle stage of the growth cycle is the flowering stage. It takes about 20 to 30 days and requires a slightly higher level of phosphorus and potassium to aid fruit development and help prevent disease. The amount of phosphorus and potassium should continue to increase slowly as the plant progresses into the fruit formation phase. At this time, it’s recommended to begin reducing the amount of nitrogen.

After about 20 to 30 days, the plant progresses to the final stage of life, known as the mature fruiting phase. This phase will usually last about 15 to 20 days and during this time, the plant needs lower levels of nitrogen and higher levels of both phosphorus and potassium. It’s also a good idea to add calcium as a micronutrient to increase fruit yield and prevent blossom rot. 

FAQs

Q: When should you fertilize your tomatoes?

The soil should be fertilized when you plant your tomatoes, and then should be fertilized again when the plant begins forming tomatoes. After this point, continue adding a light amount of fertilizer about every 1 to 2 weeks, paying careful attention to the tomato plants. Keep in mind that you can over-fertilize tomatoes, which results in tall, spindly growths and very few flowers.

Q: How much does tomato fertilizer cost?

Trying out various tomato fertilizers is a good way to find a product that works for your garden. These products are typically very affordable, so you won’t need to worry about a big price differential between fertilizers. You can expect to pay about $5 to $30 for a top tomato fertilizer.

Q: What happens if you over-fertilize tomatoes?

Adding too much fertilizer to your tomato plants isn’t going to kill the plants, but you also won’t get a very good yield. If you suspect that you over-fertilized the plants, look for common signs like tall, spindly stalks with a lot of very deep green foliage. When you’re preparing the garden in the spring, it’s recommended to apply fertilizer to the soil and till the fertilizer and soil to a depth of about 12 inches. However, this is just a guideline and you should always check the manufacturer’s directions for the best application directions to prevent over-fertilizing the tomatoes.

Final Thoughts

Keep pets and kids safe with our top choice, the non-GMO Dr. Earth Home Grown Tomato, Vegetable & Herb Fertilizer, or opt for our best value pick, Jobe’s Tomato Fertilizer Spikes, if you want an easy, affordable way to add fertilizer to the garden without producing runoff.

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