Sweet, juicy homegrown tomatoes are the epitome of backyard garden produce, and they don’t happen by accident. It takes a healthy combination of diligence, patience, sunshine, and soil fertility to grow tomatoes successfully. In fact, according to the International Plant Nutrition Institute, plant nutrition is one of the primary contributors to tomato flavor and quality.
To grow the best tomatoes, you need to fertilize them. The best fertilizer for tomatoes supports overall plant growth, flowering, fruit development, and disease resistance. A well-nourished tomato plant will yield a delicious crop of fruit. Choosing the best fertilizer for your tomato plants and growing conditions involves exploring more deeply. Check out some of the top contenders.
- BEST OVERALL: Dr. Earth Home Grown Fertilizer
- BEST VALUE: Jobe’s Tomato Fertilizer Spikes
- GRANULAR PICK: Burpee Organic Tomato and Vegetable Plant Food
- WATER SOLUBLE PICK: Greenway Biotech Tomato Fertilizer 4-18-38
Types of Fertilizer for Tomatoes
Tomato fertilizers come in three basic forms: granular, liquid, and water-soluble. Each form includes both inorganic and organic fertilizer choices. The time of year, plant health, weather conditions, user convenience, and other factors influence which formulation will best serve the gardener’s needs.
Granular fertilizer is easy to apply, requires no preparation time, and stores indefinitely in a cool, dry location. Gardeners apply granular fertilizer either by incorporating it into the soil before planting or by spreading it over the root zone of established plants. Granular fertilizers come in quick-release or slow-release formulas.
Slow-release fertilizer breaks down slowly for a long, steady feed, for up to a full growing season. Gardeners can find slow-release formulas as organic or inorganic products. Quick-release fertilizers are made of inorganic ingredients that run through the soil as they dissolve by water. This provides a quick burst of nutrients.
Liquid fertilizer comes in a concentrated form that must be diluted with water. It comes in both inorganic and organic options and is immediately available to plants. In addition to the normal application method of drenching soil around plants with liquid fertilizer, many gardeners apply weak liquid fertilizer solutions (half-strength or less) directly to plant foliage.
There are numerous ways of applying liquid fertilizer, from a simple watering can to calibrated hose-end sprayers that mix the concentrate with the flow of water as it is discharged. Liquid fertilizer provides a quick burst of nutrients and must be reapplied often. It has a long shelf life if unopened and stored properly.
Water-soluble fertilizer combines the storage convenience of granular fertilizer with the fast-acting capability of liquid forms. It becomes available to plants immediately upon application. Like the other types of fertilizers, water-soluble ones come in both organic and inorganic options.
Water-soluble fertilizer is available in a micro granule or powdered form that easily dissolves in water. The uses of water-soluble fertilizer mirror those of liquids.
What to Consider When Buying Tomato Fertilizers
Each garden is unique. Differences in soil structure, natural fertility, drainage, pH, and other factors mean that no single fertilizer works best in all cases. It helps to have different options at hand for nutrient levels that can fill plants’ needs at different stages of development. Consider these factors while shopping for the best tomato fertilizer.
Condition of the Soil
The surest way of knowing if a garden is up to the task of growing tomatoes is to have the soil tested. A soil analysis shows the current levels of all major nutrients and micronutrients in your soil. The results will include recommendations for soil amendments to add that help bring the soil into the proper range for gardening.
Each state in the U.S. operates a cooperative extension service that assists farmers and home gardeners with growing crops. Soil testing is one of the services they provide for a small fee, typically between $15 and $20. Simply type “[your state’s name] extension service” into your browser to get started.
Chemical Fertilizer Content
Fertilizer is made up of three major nutrients: nitrogen (N), phosphorus (P), and potassium (K). Nitrogen is the element responsible for foliage growth. Phosphorus helps with root, flower, and fruit production. Potassium builds strong stems and overall plant health. Manufacturers list the major nutrients prominently on the label in a ratio, such as 4-6-4, always in the order of N-P-K. The ratio tells each nutrient’s percentage share of the fertilizer’s volume. Fertilizer with a 4-6-4 ratio is 4 percent N, 6 percent P, and 4 percent K.
In addition to including the major nutrients, fertilizers may or may not contain micronutrients. Micronutrients typically appear in a less prominent location on the packaging. Micronutrients play smaller but crucial roles in various plant processes. Tomatoes notably benefit from calcium, magnesium, sulfur, manganese, zinc, boron, and copper.
Growing Stages of Tomato Plants
Early in life, as the plants become established and grow rapidly before flowering, tomato plants need nutrients that support root, stem, and leaf development. A balanced ratio of nitrogen, phosphorus, and potassium works best at this stage. Slow-release fertilizer applied at planting time can provide all the necessary major nutrients needed for the growing season.
During and after flowering, tomato plants need slightly different resources for flower production, fruit development, and disease resistance. During the fruiting phase, mature tomato plants benefit from lower nitrogen levels and higher levels of phosphorus, potassium, and some micronutrients. Calcium is especially important in promoting fruit set and preventing blossom end rot.
Organic tomato fertilizers are derived from certified organic ingredients. These formulations have a lower concentration of nitrogen (N), phosphorus (P), and potassium (K), and provide higher levels of micronutrients than inorganic products. Organic fertilizers are less likely to damage plants or contribute to water pollution in the event of a spill or other accident.
Most organic fertilizers become available to plants through microscopic organisms in the soil, like fungi and bacteria. The microbes consume the fertilizer components and then release the nutrient compounds that plants can metabolize. Organic fertilizers support broader soil ecology compared with inorganic fertilizers.
Our Top Picks
Check out this list of recommendations to help choose one of the best fertilizers for your tomatoes. These products boast quality, value, and track records of growing big, healthy, great-tasting tomatoes.
From Dr. Earth, this tomato, vegetable, and herb fertilizer is comprised of high-quality human- and feed-grade ingredients, while being enriched with multi-minerals, proteins, carbohydrates, humic acids, and trace elements. The fertilizer promotes healthy soils that help grow high-quality, nutritious vegetables at home.
Granular organic fertilizers like this are easy to use and long-lasting. Dr. Earth’s is a bit more expensive than other products, but it’s a fair price for high-quality ingredients and beautiful, delicious tomatoes. This fertilizer, produced sustainably in the United States, makes the list of Non-GMO Project-verified fertilizers as well as the Organic Material Review Institute’s list for organic gardening. The NPK ratio is 4-6-3.
- Type: Granular
- Organic: Yes
- NPK Ratio: 4-6-3
- High quality human- and feed-grade ingredients
- Promotes healthy soil
- People and pet safe
Get the Dr. Earth fertilizer at Amazon, The Home Depot, and Walmart.
Measuring and mixing fertilizers, carefully spreading or spraying them, and storing leftovers are all in the past. Jobe’s tomato fertilizer spikes eliminate time and space wasted on fertilizing with granules and liquids. Simply push the spikes in the soil and plants stay healthy and strong up to 8 weeks.
These fertilizer spikes provide nutrition underground where plant roots can use it. This makes it useful for container gardens, raised beds, or in-ground gardens. Inserting the spikes around the plants means the slow-release formula will feed tomato plants for up to eight weeks.
An advantage of fertilizer spikes is that nutrients do not wash away as easily as those in surface-applied fertilizers. The specially formulated, premeasured spikes make for fast, easy, and mess-free fertilizing. The NPK ratio is 6-18-6.
- Type: Spikes
- Organic: Yes
- NPK Ratio: 6-18-6
- Slow-release formula
- Continuous supply of nutrients
- Spikes may arrive broken or crumbled
Get the Jobe’s fertilizer spikes at Amazon, The Home Depot, and Walmart.
Burpee’s organic tomato and vegetable plant food offers an excellent slow-release organic fertilizer that comes in granular form. Tilling the granules into the ground or incorporating them into container soil at planting time makes a great start to the season. Gardeners can apply the fertilizer again as a top dressing eight to twelve weeks later for a full season of strong, healthy growth and large, colorful, tasty tomatoes.
Easy-to-spread granules release essential nutrients immediately and continue to feed for up to three months. This formula contains beneficial microbes and nutrients for excellent results throughout the season and makes the Organic Material Review Institute’s list for organic use. The slow-release granular fertilizer helps young bedding plants, established vegetables, and container plantings. The NPK ratio is 3-6-4.
- Type: Granular
- Organic: Yes
- NPK Ratio: 3-6-4
- Slow-release granular fertilizer
- Feeds for up to 3 months
- Easy to apply
Get the Burpee plant food at The Home Depot.
Greenway Biotech Tomato Fertilizer comes in a simple package that houses a professional formulation of quality ingredients specifically designed for tomatoes. This is a great product for growers who prefer a water-soluble formula, or who grow tomatoes hydroponically.
Five pounds of Greenway Biotech Tomato Fertilizer makes 1,000 gallons of liquid fertilizer. The package includes instructions for applying the product as a foliar fertilizer or as a dry product to side-dress tomatoes in the garden. This fertilizer contains no heavy metals or harmful materials. It includes the micronutrients boron, copper, iron, manganese, zinc, and molybdenum. The NPK ratio is 4-18-38.
- Type: Water-soluble
- Organic: Not specified
- NPK Ratio: 4-18-38
- Makes 1,000 gallons of liquid fertilizer
- Great for hydroponics
- No heavy metals
- Need to add calcium nitrate and epsom salt
Get the Greenway Biotech fertilizer on Amazon and at Walmart.
Our top pick for the best fertilizer for tomatoes, Dr. Earth Home Grown Fertilizer, was selected based on fertilizer type, content, ingredients, organic certification, and quality.
How We Chose the Best Fertilizers for Tomatoes
Plant and soil nutrition is key to growing plump and juicy tomatoes. A healthy tomato plant is a fertilized tomato plant. The best fertilizers for tomatoes support healthy plants, flowering, tomato development, and resistance to disease and rot.
To determine the best tomato fertilizers on the market, we focused on granular, liquid, and water-soluble options. We also looked at fertilizers that work best in certain types of soil, ease of use, chemical content, nutrients, the growing stages of tomato plants, and organic options. Our top picks will help you grow beautiful tomatoes in your garden, patio containers, or hydroponic grow room.
Before applying that new fertilizer, have a look at these answers to frequently asked tomato fertilizer questions.
Q: How much fertilizer do tomatoes need?
Timing, frequency, and application rates vary by product. Be sure to follow the application instructions on the fertilizer label.
Q: How do you put fertilizer on tomato plants?
Apply granules either by incorporating them into the soil before planting or by spreading them on the soil surface after planting. Prepare liquids according to the label instructions and drench the soil around the tomato plant.
Q: How often do you fertilize tomato plants?
Each fertilizer product breaks down or is used by the tomato plant a little differently. If using granules, applying two or three applications through the growing season usually suffices. Apply a liquid fertilizer every two or three weeks. Use caution and read product labels.