“My Neighbors laughed when I ordered my GrowBoxes™ Now, THEY ALL want a tomato garden like mine!”
what nutrients are needed for tomatoes to grow

What Nutrients Are Needed for Tomatoes to Grow?

Tomatoes are a hungry bunch. They need rich soil to grow properly and produce a high yield, and these plants are notoriously picky eaters. Feeding your tomatoes the right nutrients at the right time is a must. Otherwise, you risk ending up with a sickly plant or a super-bushy, healthy-looking thing that won’t blossom or yield fruit.

So, what nutrients are needed for tomatoes to grow? At Garden Patch, we put together this guide to help you grow juicy, healthy tomatoes to enjoy all summer long. One of the best things you can do to ensure a healthy tomato crop is use the GrowBox, which comes prebalanced with all the nutrients your tomatoes need. Take the guesswork out of gardening with a planter that plants, waters, and fertilizes for you!

The Most Important Nutrients for Tomato Growth

Tomatoes require macro and micronutrients at different stages of their lives. Enriching the soil with tomato fertilizer, such as the organic fertilizer from Jobe’s, can ensure that your plants have everything they need to develop properly. 


Like all plants, tomatoes require three main macronutrients to stay alive: nitrogen, phosphorus, and potassium. All three are essential for photosynthesis and various other functions. Other important macronutrients include calcium, sulfur, and magnesium.


Nitrogen is critical for healthy leaf growth and flower and fruit development. Your tomatoes need the most nitrogen during the seedling stage and just before flowering.

Good nitrogen sources include liquid fish emulsion and seed meals such as alfalfa, rapeseed, and cottonseed meal. Once the first true leaves come out, feed the seedlings with diluted fish emulsion twice monthly. Alternatively, you can mix a little seed meal into the soil around the base of each plant.


Phosphorus is essential for photosynthesis, proper root growth, and blossoming. Tomatoes need the highest amount of phosphorus in the early stages of development and especially when transplanting seedlings into the garden. 

Excellent phosphorus sources include:

  • Bone meal
  • Rock phosphate
  • Bat and bird droppings

Tomatoes absorb droppings and bone meal quickly. Rock phosphate takes a while to reach the plant but has the added benefit of enriching the soil over an extended period.

When transplanting a seedling, put one of these fertilizers into the hole. Later, mix some more fertilizer around the base at least once before the onset of blooming.


Potassium is critical for flower and fruit development. Tomatoes need this macronutrient in even greater quantities than nitrogen, especially during fruit bulking.

Kelp meal and Jersey greensand, a type of rock dust, are both excellent sources of potassium. Mix your preferred fertilizer around the base of the plant after it has been in the soil for two weeks. Do this again when it blooms, and follow up with regular applications throughout the season.


Calcium is essential for plant cell structure. Like with potassium, tomatoes need more calcium as they mature, with requirements peaking from flowering through harvest. However, 95% of this macronutrient is in the roots, stems, leaves, and other vegetative parts, so your plants also need a steady supply during their vegetative growth.


Plans use sulfur to grow, create proteins, and withstand the cold. Be sure to feed your tomatoes sulfur throughout the growing period.


Magnesium is a key ingredient of chlorophyll, the green pigment responsible for photosynthesis. Magnesium needs peak around flowering time, but a steady supply is essential throughout the season.


Tomatoes require much lower levels of these trace micronutrient elements, but they are still critical for optimal plant health and high yields.

Boron and zinc are especially important. Boron promotes flower development, pollen viability, fruit ripening, and structural integrity. Zinc is essential for growth. 

Other vital micronutrients include:

  • Iron
  • Copper
  • Manganese
  • Molybdenum

Kelp meal and dolomite lime are rich in micronutrients. Mixing dolomite lime into the soil before planting also lowers the acidity of seed meals and brings the soil’s pH to neutral, which tomatoes like.

Aged compost and aged manure not only have a great balance of macro and micronutrients but also improve soil quality over time. A good rule of thumb is to spread manure or compost around the base of the plants once or twice during the growth cycle. 

Signs of Nutrient Imbalances in Tomatoes

Plants can suffer from having too little or too much of certain nutrients in their diet. For instance, too high nitrogen, potassium, and magnesium levels all cause blossom end rot. 

Excessive nitrogen can promote extreme leaf growth at the expense of fruit development, especially in young plants that have not yet flowered. The result is often a bushy plant with tiny or no fruits.

Other symptoms of too much nitrogen include:

  • Burning of the roots, especially in young plants 
  • Damping off in seedlings
  • Worsening tomato pith necrosis, a bacterial infection causing black stems

Tomatoes with potassium deficiency will likewise have few fruits or none at all. You should also watch for cracks in the fruits and yellowing around the part of the fruit near the stem.

What Nutrients Are Needed for Tomatoes to Grow? End the Guesswork with Garden Patch’s GrowBox!

Tomatoes are just like us: They don’t need much to survive, but it takes a rich and complex diet for them to thrive. With the Garden Patch GrowBox, striking the right nutritional balance at all development stages of your plants is easy, even without any gardening experience.

We designed the GrowBox to enable easy set-up and perfect plant spacing with no need for digging.

After that, GrowBox automatically feeds and waters the plants for you with the right amounts of fertilizer at just the right time. The planter set comes with free nutrient packs that have everything tomatoes need for optimal health, including dolomite lime.

Instead of stressing about what nutrients are needed for tomatoes to grow, you can focus on the best parts of gardening: watching your beautiful plants thrive and, when the time comes, enjoying the delicious ripe tomatoes with family and friends.

Order your GrowBox online or by phone at (800) 519-1955.

To learn more about tomatoes’ nutritional needs, check out our article on the differences between plant food vs. fertilizer.

did you find this article helpful?
If so, why not share it now on these social media platforms.

Other Growing Guides Articles

How Deep Do Tomato Roots Grow?

With the proper TLC, tomato plants can provide a bountiful harvest of plump and delicious fruits. While many different factors impact the health and yield of tomatoes, their root system is one of the most important. Have you ever wondered, "Just how deep do tomato roots grow?" Wonder no more because today, you'll find the…

A Garden Patch
how deep do tomato roots grow

Determinate vs. Indeterminate Tomatoes: Understanding the Differences

Cultivating homegrown tomatoes can be fun, but do you know the differences between determinate and indeterminate tomatoes? Many amateur planters aren’t sure which type of tomato is best for their gardens. Learning the differences between determinate vs. indeterminate tomatoes can help you know what to expect during harvest. At A Garden Patch, our experienced crop…

A Garden Patch
determinate vs indeterminate tomatoes

Understanding Nutrient Deficiency in Tomatoes

Who doesn’t love a big, juicy tomato? Many home gardeners quest after the perfect tomato, but it’s not as simple as sticking seeds in the ground and letting them grow. If you fail to give your plants adequate nutrition, you’ll have disappointing yields, poor growth, and mealy, tasteless tomatoes. The passionate folks at A Garden…

A Garden Patch