Feed Tomato Plants: Best Timing And Methods

Last Updated on August 16, 2022 by Real Men Sow

Tomatoes are the ultimate summer vegetable. While tomatoes may seem easy to grow, some people are not aware of the fact that they can be very picky about soil conditions, water requirements, and fertilizing frequency. This means that you must know how often tomatoes should be fertilized.

How often and when should you feed tomato plants?

You must fertilize tomatoes as seedlings, as well as when they are transplanted outside. After the flowers start to grow, fertilize once more. Light fertilizer should be applied once every two weeks to the plant until it produces fruits.

You need to be able to determine when and how much to fertilize your tomato plants to get the best results. This can make all the difference between a strong harvest and a weak crop. Let’s get to the bottom of it together.

What Nutrients Do Tomato Plants Need?

Tomatoes need lots of nutrients to grow well. They are heavy feeders. Your plants will only harvest a small amount of food if you don’t fertilize. The three main nutrients that tomatoes need are nitrogen, phosphorus and potassium (NPK). There are also a host of nutrients that they may require. Each of these nutrients plays a vital role in the plant’s health. Let’s look at just a few.


This nutrient is important for the health of the leaves. However, too much nitrogen can cause a bushy plant that bears little or no fruit. This would be a major problem.


Phosphorus is an essential nutrient at both the beginning and the end of growth.


This nutrient aids the plant to grow quickly and produce flowers that then turn into fruits. Potassium is vital for photosynthesis and disease resistance.


Add calcium to your tomato plants, and it focuses more on root and leaf growth. It’s also necessary for the production of firm tomatoes.


It helps plants to stay green. Magnesium also improves flowering and fruit quality.

Zinc and Boron:

Thye are essential elements that help plants with flowering and fruit ripening.

How Do I Know If My Tomatot Plants Need Nitrogen?

Nitrogen is one of the most important nutrients. However, it can quickly become depleted if your soil isn’t prepared correctly in its early stages. A soil rich in rich humus will usually have plenty of nitrogen. The yellowing of the tomato plants’ bottom leaves is often an indicator that they need more nitrogen. Your leaves are a good indicator of soil problems.

What Is The Best Fertilizer For Tomato Plants

A fertilizer should contain all the macronutrients your plants need, such as nitrogen, phosphorus, and potassium. It must also contain essential micronutrients such as magnesium, calcium, and boron. Problem is, that tomatoes require all these nutrients in different amounts at different times during their growth cycle. This can make it difficult to choose the right one.

Use multiple fertilizers to feed tomato plants

At all times of the growing season, no single fertilizer will work for all plants. It’s part of gardening to have multiple fertilizers. Commercial fertilizers will have a number series on their containers, such as 10-10-10. NPK stands for nitrogen, phosphorus, and potassium. A 10-10-10 represents 10% nitrogen, 10% Phosphorus, and 10% potassium. The rest are filler materials.

It is also smart to test your soil before fertilizing:

  • You should choose a fertilizer with a lower nitrogen content and higher phosphorus level if your soil is acidic or high in nitrogen.
  • A balanced fertilizer, such as a 10-10-10, will help your soil get enough nitrogen.
  • You don’t have to add nitrogen to the soil if you are using compost or aged manure. You will only need to add phosphorus in the first stage of the plant’s growth after it has been transplanted

The Best Phosphorus Fertilizers For Feeding Tomato Plants

You might not need to add phosphorus, depending on how your garden beds were prepared. This is possible when you add lots of compost to your soil, making sure it has enough nitrogen. For tomato growth, phosphorus is still required.

It’s best that you use bonemeal or organic fertilizer spikes to increase phosphorus. Some people do not like a bone meal as it is an animal byproduct. You can purchase traditional phosphorus fertilizer, which is synthetic but not from animals if you feel this way.

Bone Meal

Bone meal, a by-product of an animal, can be used to fertilize your seedlings for strong root growth. This fertilizer is usually made from ground-up bones of animals, such as beef bones. However, other bones may be used. The majority of bone meal that you can buy in a store has a ratio between 3-15-0 and 3.

It is important to know that bonemeal can take up to 4 months to completely break down in soil. To determine how much phosphorus is in your soil, it is a good idea to test it. On average, 1 pound per 10 feet is enough for the entire growing season.

Fertilizer Spikes

You’ll find a wide variety of fertilizer spikes at your local garden shops. You just need to place the spike six inches from your stem. This includes container-grown tomatoes. A fertilizer spike with a higher phosphorus content and average levels of nitrogen or potassium is recommended. A fertilizer spike usually lasts for about two months. This makes it an economical and easy way to fertilize your plants.

Compost Tea – A Fantastic Option

Compost tea is another fertilizer that tomato plants love. You can increase the amount of potassium you require. To do this, add banana peels. Banana peels can be chopped up and buried in the soil around plants to increase potassium.

Make compost tea by scavenging the leaves and placing them in a cheesecloth bag. You can also add a few banana peels. Next, place the cheesecloth bag into a 5-gallon bucket and let it sit for several days. Once you are ready, water your plants with the compost tea. This is an easy way to give your plants a boost.

When And How Often To Fertilize Tomatoes

Tomato plants require fertilization at different times. Each stage is crucial and plants will not succeed in the next step without the proper nutrients. This is the time to fertilize your tomatoes.

Add Compost When You Prepare Garden Beds

Preparing the garden beds is essential before you start planting. Preparing the garden beds for the next season should be done in spring. You should add compost or aged manure to your garden beds before you plant. Compost is a valuable resource. It’s high in nitrogen which is essential for all vegetables, including tomatoes. It’s possible to make your garden beds look great if you add 4 to 6 inches of compost. Your garden beds are now ready for planting. You are now ready to plant huge tomato plants!

Fertilize Your Tomato Seedlings

If you have started tomato seeds yourself, fertilize them once they sprout and germinate. Tomato seedlings can grow quickly, sometimes surprisingly fast. The average time between the moment tomato plants sprout and the time they bear fruit is four months. Fertilize your seedlings to help them keep up with the initial surge in growth.

Fertilize When You Plant Your Tomato Seedlings

You haven’t fertilized your seedlings in a while, so it’s time to let them go outside and plant their big garden beds. They are about to experience a significant growth spurt and will need lots of nutrients to get them through it.

You don’t have to add nitrogen if you fill your garden with compost or aged manure. Adding more nitrogen could endanger your plants, which could lead to them burning. You should instead add phosphorus only at the beginning of your plants’ growth.

Choose the best tomato phosphorus fertilizer and plant it when you plant your tomato seedlings. You might not need fertilizer if you composted a lot of banana skins and bones. It would be important to add a lot of these items and be deliberate about it.

Fertilizing When Flowering Starts

Your plants will need plenty of potassium and nitrogen during this stage. If you want strong, healthy growth and more flowers, potassium is vital. The potassium level should be at minimum twice that of your nitrogen. You can either use an 8-32-16 fertilizer or a 6-24-24 fertilizer at this stage. Follow the instructions on your package.

Watch For Fruit Growth And Add Extra Fertilizer 

You can now wait! Now, wait for your plants to reach the size of a golf-ball. The next fertilizer dose should be applied once the first fruits appear. This will encourage fruit production. This stage is where phosphorus and potassium are essential nutrients. To ensure that the compost tea has enough potassium, add more banana peels. But the star of this show should be phosphorus or nitrogen.

Assuming that your compost was added correctly, we will continue to assume that it provided all the necessary nitrogen for proper growth. Most garden soil has enough phosphorus. However, if your fruit is not developing properly, you may need to add more fertilizer. You can choose an 8-32-16 fertilizer at this point.

Light Fertilizing Until The End Of The Season

You can fertilize lightly every two to three week from now through the harvest period. Don’t overfeed. This stage is where phosphorus and calcium still play a crucial role in producing fruit. Indeterminate tomato plants should be fertilized more often. You don’t have to fertilize as often if you have determinate plants. They focus on one thing: their fruit growth. You should have enough phosphorus fertilizer.

One Size Doesn’t Fit All

These are just general recommendations. However, it is up to you to experiment and find what works for you. There is no one fertilizing method that will work for everyone. Here are some considerations.

  • You will need to fertilize more if your soil is sandy than if it’s sticky or clay-like. Because sandy soil is not able to hold nutrients well, they will quickly be washed away.
  • Plant tomatoes in containers to get more nutrients quickly. You should fertilize your tomatoes more often than with in-ground tomatoes.
  • Never apply fertilizer to the leaves.

The Right Way To Feed Tomato Plants

There are two ways to feed tomato plants. Incorrectly feeding your tomato plants could result in them not absorbing the nutrients or burning. You should be aware of a few things when fertilizing tomato plants.

Add Organic Matter First

Before you plant, it is a good idea to add a few inches more organic matter to your soil. This is especially important if you do not intend to use synthetic fertilizer. The addition of 8-12 inches organic matter to your soil improves drainage and provides many vital nutrients for plants.

Watch Where You Fertilize

Applying fertilizer to the entire plant is not recommended. Fertilizing too close could result in fertilizer running off the stem and burning the plant. It is important to avoid fertilizing leaves; this can cause the same kind of burning.

Mix The Fertilizer

Mix the tomato fertilizer in the soil at the bottom before fertilizing tomatoes. The fertilizer should be at least six inches from the plant to prevent it burning. It will still be able to access the nutrients. Dig a small hole around the base of your plant and sprinkle the fertilizer. Then, cover the soil with the unfertilized soil.

Understand Natural Vs. Synthetic Fertilizers

  • Natural fertilizers can be either animal- or plant-derived. Synthetic fertilizers contain potassium, nitrogen and phosphorus.
  • Synthetic fertilizers are not necessary if the soil is rich in organic matter. In small doses, however, a balanced fertilizer will not harm your plants.

Water Tomato Plants Correctly

It doesn’t matter what fertilizer you use or how often you apply it if the plants don’t absorb the nutrients. For proper root health, you must ensure that your plants are properly watered. Always water the stems of your plants slowly and deeply. Allow enough time for water to reach the soil and absorb. It is best to water in the morning or in the evening, when it isn’t too hot.

Each week, tomato plants require 1-2 inches of water. Water must be applied before fertilizing. You should water the entire plant from the base. Spread the fertilizer onto the soil. The nutrients will eventually reach the plants.

How Do I Know If I Fertilized Tomato Plants Too Much?

There is a limit to how much fertilizer you can apply to your plants. Too much fertilization can cause the plant to die quickly. How do you find out if this happened? Is there a way to correct an over-fertilization?

Signs of Overfertilization

  • Yellowing Leaves
  • Bushy Leaves
  • Delayed Flowers
  • Sediment Build Up on Soil Surface
  • Yellowing & Wilting Lower Leaves
  • A Sudden Loss of Leaves

How To Fix Your Tomato Plants When You Overfertilized Them?

If you see a few of these signs it is usually an indication that you added too much fertilizer. It was your intention to do the right thing, but it is often possible to fix it. Here’s what you should do.

Add Mulch

It is not enough to just add mulch. You need organic mulch that will eventually decompose. You need nitrogen to decompose. If you have additional nitrogen in your soil, add a layer of sawdust. For even better results, mix the sawdust with the soil.

Scrape Off The Sediment

You might find a layer of white salts or sediments on top of your soil if you apply too much fertilizer. This layer can be removed and disposed of to aid in soil healing.

Soak The Soil

Soak the soil well if you have raised plants or grown in containers. This allows the water to drain out. If you are doing in-ground gardening, make sure to soak your plants several times. This is known as flushing or leaching the soil.

Fertilizing Tomato Plants Is Essential

Your tomato plants won’t reach their full potential if they aren’t properly fertilized. To grow tomatoes correctly, gardeners must know when to fertilize tomatoes and what nutrients they need at each stage. You should water well before you plant and keep fertilizer off the foliage.

Real Men Sow
Real Men Sow

Hello, I’m Pete and I’m currently based in the west of Scotland, in a small place called Rosneath, where I’m exploring my garden adventures. I personally started gardening around 6 years ago and initially, I started out by growing my favorite fruits and berries, such as strawberries, Raspberries & Gooseberries. Since then I’ve added a lot of vegetables and working closely with my neighbor, it’s been a lot of fun.