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 the other plants and veggies in your garden.
One of the secrets to growing great tomatoes is using a fertilizer specifically for tomatoes, and not using an all-purpose fertilizer or, worse yet, no fertilizer at all.
Here are the best fertilizers for tomatoes.
Tomato-tone Organic Fertilizer
The Tomato-tone Organic Fertilizer from Espoma is a natural fertilizer for great tomatoes and fruiting vegetables like peppers, squash, and melons. It can be used 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, and all the essential nutrients tomato plants need.
It contains microbes that promote healthy soil and provide long-lasting, slow-release plant food. Tomato-tone has been university tested and proven to consistently produce plump, juicy tomatoes, and it’s organic and environmentally safe.
A 4 lb. bag of Tomato-tone Organic Fertilizer is enough to prepare a 50 square foot vegetable bed in the spring, or feed a 10 foot row of tomato plants for three months in the summer.
Jobe’s Organics 9026 Fertilizer
Jobe’s Organics Vegetable and Tomato Fertilizer is designed for tomatoes, but 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 that improve your soil quality and help your tomato plants resist disease and drought.
It’s a fast-acting fertilizer that can be used 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
The Miracle-Gro Tomato Plant Food is a water-soluble tomato food with an 18-18-21 formula.
It’s good for tomatoes and all vegetables, and creates bigger, more productive plants.
It’s easy to use by simply diluting in a sprayer or watering can, works quickly, and is guaranteed not to burn plants when used as directed.
Dr. Earth Organic 5 Tomato, Vegetable & Herb Fertilizer Poly Bag
Dr. Earth Organic 5 Tomato, Vegetable & Herb Fertilizer is 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 or nourishing seedlings, or to feed established plants, and feeds for several months.
It contains pro-biotic beneficial microbes and ecto and endo mycorrhizae to sustainably improve soil, without harming kids or pets. Dr. Earth Organic Tomato Fertilizer is sustainably produced in the USA and is environmentally friendly.
JR Peters 51324 Jack’s Classic 12-15-30 Tomato Feed
The JR Peters Tomato Feed is a water soluble 12-15-30 formula ideal for feeding tomatoes and other fruiting vine vegetables like peppers, cucumbers, and squash.
Additional potassium helps to create green leaves, strong vines, and more fruit per plant. It also has additional calcium to prevent blossom end rot, and magnesium for improved results.
This fertilizer is made with high-quality nutrients, and it comes with a measuring spoon for consistent feeding.
TeaDrops Organic Liquid Plant Food & Vegetable Fertilizer Packets
The TeaDrops Organic Liquid Plant Food comes in an innovative packet that is incredibly easy to use with no mess and no measuring. Simply use the fertilizer packets and steep them in water to make a healthy compost tea that 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 that naturally nourish the soil, along with naturally-occurring plant growth hormones.
This fertilizer can be used to soak seedling roots, as a seedling mist, as a foliage spray, as a root drench, or as a simple plant food that will never burn your plants. It’s 100% organic and pet and child friendly, and is sustainably made in the USA. After use, the packets can simply be tossed into your composter, or opened and sprinkled onto your garden soil to add natural nutrients.
Neptune’s Harvest Tomato & Veg Fertilizer 2-4-2, 36 oz
Neptune’s Harvest Tomato & Veg Fertilizer is a liquid fish fertilizer with a 2-4-2 formula for use on tomatoes and vegetables.
Made with fish, seaweed, molasses, yucca extract, and humic acids, it’s the right nutrient balance for plants that have intense growth during fruiting stages.
This fertilizer improves stalk and stem mass, and supports strong roots and lush foliage. It makes plants more tolerant to drought and disease. It’s designed for use during the vegetable stage of the plant.
Tomato Fertilizer Buyer’s Guide
Difference Between Fertilizer and 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 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 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 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 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.
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 helps plants use nutrients effectively, and is required for the growth of fruits and seeds.
Zinc helps plants create carbohydrates and sugars, and form the enzymes needed during growth.
While a healthy tomato requires all those nutrients, it isn’t as simple as purchasing a fertilizer that is high in all those values and using it on your tomato plants.
All your plants will get most of the nutrients they need from the soil they grow in; a fertilizer needs to complement and enhance the nutrient levels in your soil. For example, if your soil is already high in nitrogen, then you should choose a fertilizer with less nitrogen.
The best fertilizer for tomatoes also depends on what stage of growth the plant is in.
A tomato plant needs different nutrients when it is a seedling, to promote healthy roots and leaves, than it does as a mature plant, to promote large fruits. The best tomato plants get the right nutrients at every stage of growth.
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 Fertilizer 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 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 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 are growing tomatoes from pre-packaged seeds, the label will tell you if you have a determinate or indeterminate variety.
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:
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.
Use a seedling mix. Seeds typically do not need additional nutrients.
Tomato plants need sufficient potassium and phosphorus to grow healthy roots.
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.
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.