The Best Fertilizers for Tomatoes – 7 Top Picks

The best fertilizers for tomatoes is a matter of preference. But we’re going to tackle the topic here. There’s nothing like the flavor of fresh tomatoes from your own garden. But tomato plants can be tricky to grow, with more and different needs than other plants and veggies in your garden.

One of the secrets to growing great tomatoes is using a fertilizer formulated for tomatoes. You’ll find more success that way than by using an all-purpose fertilizer or, worse yet, no fertilizer.

Here are the best fertilizers for tomatoes:

Tomato-tone Organic Fertilizer from Espoma is one of the best fertilizers for tomatoes. The organic formula helps you produce great tomatoes and fruiting vegetables, like peppers, squash, and melons. You can use it as a pre-seed soil enhancer, and to feed new and established plants. It’s a 3-4-6 fertilizer with 8% calcium to prevent blossom end rot. It has all the essential nutrients tomato plants need.

Tomato-tone contains microbes that promote healthy soil and provide long-lasting, slow-release plant food. It’s been university-tested and proven to produce plump, juicy tomatoes consistently. Plus, it’s organic and environmentally safe.

A 4 lb. bag of Tomato-tone fertilizer is enough to prepare a 50-square-foot vegetable bed in spring. Alternatively, it can feed a 10-foot row of tomato plants for three months in the summer.

Jobe’s Organics Vegetable and Tomato Fertilizer is designed for tomatoes. However, it benefits all your edible plants, including cabbages, squash, garlic, cucumbers, and more.

It’s a 2-5-3 fertilizer with 7% calcium that has been OMRI-certified for organic gardening.

This fertilizer contains the proprietary Jobe’s Biozome blend of healthy bacteria, fungi, and other microorganisms. These ingredients improve your soil quality and help your tomato plants resist disease and drought.

It’s a fast-acting fertilizer you can use for soil preparation and to feed new and established plants. Jobe’s Organics are renewable, sustainable, kid-and-pet-friendly, and good for the environment as well as your vegetable garden.

Miracle-Gro Tomato Plant Food is a water-soluble tomato food with an 18-18-21 formula. It’s suitable for tomatoes and all vegetables and creates larger, more productive plants.

It’s easy to use by diluting it in a sprayer or watering can. Also, it works quickly and is guaranteed not to burn plants when used as directed.

Dr. Earth Organic Tomato, Vegetable & Herb Fertilizer is next on our list of the best fertilizers for tomatoes. It’s a 4-6-3 fertilizer that creates healthy soil to produce the healthiest tomatoes, vegetables, and herbs.

This fertilizer formula is OMRI-Certified, OIM-Certified, CCOF-Certified, NOP-Certified, and Non-GMO-Project-verified. It can be used during transplanting, for providing nourishment to seedlings, or to feed established plants. This formula feeds for several months.

Dr. Earth’s contains beneficial probiotic microbes and ecto and endo mycorrhizae to improve the soil sustainably. And it won’t harm kids or pets. Dr. Earth Organic Tomato Fertilizer is sustainably produced in the USA and is environmentally friendly.

The Jack’s Classic Tomato Feed is a water-soluble 12-15-30 formula. It’s ideal for feeding tomatoes and other fruiting vine vegetables like peppers, cucumbers, and squash.

Additional potassium helps to create green leaves, healthy vines, and more fruit per plant. It also prevents blossom end rot and has magnesium for improved results.

This fertilizer is made with high-quality nutrients and comes with a measuring spoon for consistent feeding. 

TeaDrops Organic Liquid Plant Food comes in an innovative package that’s easy to use with no mess or measuring. Simply steep the fertilizer packets in water to make a healthy compost tea. The tea will feed and water your tomato and pepper plants at the same time.

This low NPK formula promotes plant health with organic plant fungi, bacteria, and humic acids. These ingredients naturally nourish the soil, along with naturally-occurring plant growth hormones.

Use TeaDrops to soak seedling roots or used as a seedling mist, foliage spray, root drench, or simple plant food. Best of all, it will never burn your plants. It’s 100% organic, pet- and child-friendly, and made sustainably in the USA. After using them, toss the packets into your composter. Alternatively, open them and sprinkle the contents onto your garden soil to add natural nutrients.

Neptune’s Harvest Tomato & Veg Fertilizer is a liquid fish fertilizer. It has a 2-4-2 formula for use on tomatoes and vegetables.

They make Neptune’s with fish, seaweed, molasses, yucca extract, and humic acids. It’s the right nutrient balance for plants with intense growth during fruiting stages.

This fertilizer improves stalk and stem mass and supports strong roots and lush foliage. It also makes plants more tolerant to drought and disease. They designed Neptune’s for use during the vegetable stage of the plant.

The Best Fertilizers for Tomatoes: A Buyer’s Guide

Difference Between the Best Fertilizers for Tomatoes and Regular Plant Food

While manufacturers tend to use these terms interchangeably, plant food and fertilizer are different things. Plants “feed” themselves, using the nutrients in the soil, and sunlight, and gases in the air.

Fertilizers add missing nutrients to the soil, to help provide the raw materials for plants to eat. A fertilizer is a dietary supplement for a plant, the way you may take a vitamin C tablet if your diet is low in vitamin C.

And, like human supplements, more isn’t necessarily better; if your body already has as much vitamin C as it needs, it won’t make use of the nutrition in the tablet, and it will just pass through the body as waste.

Because excess nutrients aren’t actually healthy for the soil, and can cause environmental problems with water runoff and pollution, it’s important to only add the nutrients your plants need that are lacking in your soil, and choose just the right fertilizer for your garden. 

Types of Tomato Fertilizers

Chemical Fertilizer Content

Fertilizers are denoted with a sequence of three numbers that identifies the percentage of the primary plant nutrients.

Nitrogen (N)

Nitrogen is part of chlorophyll, and necessary for all living cells. It improves plant growth, seed production, fruit production, and the quality of the leaves.

Phosphorus (P)

Phosphorus is also essential for photosynthesis, and helps to transform solar energy into oils, starches, and sugars in plants. It speeds plant growth, and encourages healthy roots and flowers.

Potassium (K)

Potassium also helps in photosynthesis, and improves fruit quality and disease resistance.

When a fertilizer gives a label of, for example, 10-10-10, that means it has 10% nitrogen, 10% phosphorus, and 10% potassium. But those aren’t the only nutrients that healthy tomato plants need. Tomato plants also require:

Calcium (Ca)

Calcium builds healthy plant cells and makes for stronger plants. It also helps balance the pH in a plant. In tomatoes, it prevents blossom end drop.

Magnesium (Mg)

Calcium and magnesium always go together, as they have a synergistic effect and operate best in tandem. Magnesium is required for photosynthesis and for the plant enzymes needed for healthy growth.

Boron (B)

Boron helps plants use nutrients effectively, and is required for the growth of fruits and seeds.

Zinc (Zn)

Zinc helps plants create carbohydrates and sugars, and form the enzymes needed during growth.

Healthy tomatoes require all those nutrients. However, it isn’t as simple as purchasing a fertilizer high in those values and using it on your tomato plants. Your plants will get most of the nutrients they need from the soil in which they grow. The best fertilizers for tomatoes complement and enhance the nutrient levels in your soil. For example, if your soil is already high in nitrogen, you should choose a fertilizer with less nitrogen.

The best fertilizers for tomatoes also depends on what stage of growth the plant is in. A tomato plant needs specific nutrients when it’s a seedling to promote healthy roots and leaves. As a mature plant, it needs fertilizer to help it grow large fruits. The healthiest tomato plants get the right nutrients at every stage of growth.

Microbial Fertilizer

Many of our best fertilizers for tomatoes also include healthy soil organisms, like fungi and bacteria, that are beneficial to the soil.

These kind of microbes are a biologic alternative to the chemical formulas that we typically use to nourish plants. Microbes form a healthy symbiotic relationship with plants, where they convert naturally-occurring nutrients in the air, soil, and water into the elemental forms more readily used by plants.

They can also help improve plant growth hormones and benefit the plants in other helpful ways.

Microbial fertilizers are a great alternative to chemicals, because using them does not deplete the soil or have negative effects on nearby plants or insects.

We don’t yet have convenient ways (like the NPK values) of measuring and labeling these microbial fertilizers, but they are an organic and environmentally-responsible way to improve the quality of your soil and the health of your plants.

How to Choose the Best Fertilizers for Tomatoes

Check the Condition of the Soil

If you are growing tomatoes in the soil in your garden, it’s best to begin with testing your soil and preparing it properly. Tomato roots generally grow 6-7 inches deep, so that’s where your nutrients need to be concentrated. You can test your soil two ways.

Use a Laboratory

It’s best to choose a lab that is local to your area, since they will be most familiar with your soil conditions, and many universities offer this service. They will provide you with a detailed report of your soil, including macro- micronutrients, chemical and mechanical analysis, pH levels, and often other details like water analysis.

Use a DIY Kit

DIY kits will give you a read of your soil’s major nutrients (NPK levels) and the pH. These kits are usually faster and more affordable than lab testing.

Testing your soil before choosing a fertilizer is important for the health of your plants and for the health of the environment. In order to add only the nutrients you need, so you need to know what your soil already has. Many home gardeners begin with a DIY kit, and only use a laboratory if they are struggling to grow healthy tomatoes and need additional information. 

If you are growing tomatoes in containers or raised beds, you can purchase a high quality growing mix that already has a nutrient balance designed for tomatoes and vegetables.

Know what Kind of Tomato Plants You Have

There are two types of tomato plants:

Determinate

Determinate tomato plants grow to a certain size, and then produce fruit that is a certain size. They typically produce tomatoes earlier in the year, and all within a 2-3 week period.

Indeterminate

Indeterminate tomato plants will keep growing as long as the season continues, and fruits will also keep growing as long as growing conditions are right. They typically produce fruit for a much longer period of time, toward the end of the summer.

Because tomato plants need different nutrients at different growing stages, it’s best to know if you have a determinate plant, with a distinct difference between growing and fruiting stages, or an indeterminate plant that needs growth, blossom, and fruit fertilizer throughout the season.

Knowing what type of tomato you have will also help you prune and manage the plant and fruit.

If you’re growing tomatoes from pre-packaged seeds, the label will tell you if you have a determinate or indeterminate variety.

On the other hand, if you have an existing tomato plant, and don’t know what type it is, here are some ways to tell:

• If your tomato plant has long branches with sparse leaves, it is likely indeterminate. Determinate tomatoes are more compact and bushy, with flowers at the terminal end of the branch, that stop the growth cycle
• If your tomato plant has suckers at the base and at stem crotches, it is likely indeterminate. Suckers only form on indeterminate tomatoes
• Note the growth size of your tomato. Determinate tomatoes are compact, usually only 2-3 feet tall and with smaller fruit. Indeterminate tomatoes can get up to 6 feet tall, with spreading branches and larger fruit.
• If your tomato produces blossoms all at once, early in the year, it is a determinate variety.

Check the Growing Stage of the Tomato Plants

The best tomato plants get the right nutrients at every stage of growth, for healthy development of roots and stems, leaves and branches, then blossoms and fruit. Because determinate tomato plants have such clear distinctions between phases, it is easy to switch to the optimal fertilizer at every stage. Indeterminate plants experience multiple stages at once, and need less specialized fertilizers. Here are the fertilizers to look for at every growing stage:

Preparing Soil

Test your soil. Consider adding compost, a microbial fertilizer, or a slow-release chemical fertilizer. Tomatoes do best in soil with an acidity of 5.8 to 6.8, so adjust the pH if necessary.

Starting Seeds

Use a seedling mix. Seeds typically do not need additional nutrients.

Developing Roots

Tomato plants need sufficient potassium and phosphorus to grow healthy roots.

Seedlings

Nitrogen is essential for healthy foliage, but sufficient nitrogen is usually available in the soil. You should avoid adding too much nitrogen as it will cause the plant to have vigorous foliage and little blossoms or fruit.

Blooming and Fruiting

Phosphorus is required for heathy production of blooms and fruit.

As a rule, tomato plants require:

• Nitrogen: 4-5.6% in the soil. Supplement with fertilizer if necessary
• Phosphorus: 0.3-0.6% in the soil. Supplement if necessary
• Potassium: 3.0-4.5% in the soil. Supplement if necessary
• Calcium: 1.25-3.2% in the soil. Supplement if necessary
• Magnesium: 0.4-0.65% in the soil. Supplement if necessary
• Sulfur: 0.65-1.4% in the soil. Supplement if necessary
• Manganese: 30-400 ppm in the soil. Supplement if necessary
• Iron: 30-300 ppm in the soil. Supplement if necessary
• Boron: 20-60 ppm in the soil. Supplement if necessary
• Copper: 5-15 ppm in the soil. Supplement if necessary
• Zinc: 30-90 ppm in the soil. Supplement if necessary

Because tomatoes consume more of different nutrients at different points in the growth cycle, it’s not a bad idea to re-test the soil with a quick test every few weeks and adjust your feeding as indicated.

The Best Fertilizers for Tomatoes – The Wrap-up

Following these guidelines will help you have the best, strongest, healthiest tomato plants possible, for an abundant harvest. Choose the right fertilizer for your soil conditions and for your tomato types, and have a delicious summer.