How to Fertilize Tomatoes – Proper Nurturing

Save for later!

Tomatoes are notorious for using up all the available nutrients in your garden. It should come as no surprise that adding the right fertilizer is an important step.

How to fertilize tomatoes: Tomatoes require a balanced fertilizer that is a solid mix of nitrogen, phosphorus, and potassium. You should add fertilizer to the soil when you plant your tomatoes but also a layer of basic soil so that the roots don’t come into contact with raw fertilizer, as this can burn them. Once your tomatoes start to produce fruit, you can add more fertilizer every two weeks. You can choose to use organic fertilizer, such as aged manure or bone meal, or you can use an inorganic fertilizer that has the right ratio for tomatoes.

Tomato fertilizing ratio

To begin with, all pre-made, inorganic fertilizers will have a ratio of nutrients in them. There should be three numbers to look for and they will always refer to the same order of nitrogen, phosphorous, and potassium.

While you can dive right in, you may want to test your soil first, to see what nutrients it currently holds. This will then ensure you are adding the right ratio of nutrients for your tomatoes.

For soil that is fairly well-balanced, you should use a tomato fertilizer of 5-10-5, which has less nitrogen in it. However, if your current soil does not have a lot of nitrogen, then a more balanced fertilizer such as 10-10-10 will do well.

Steps on how to fertilize tomatoes

Unlike other crops, tomatoes really need their fertilizer. It’s important to understand just how to add your fertilizer and remember to actually do it.

Step 1 – Start right away

As we mentioned, tomatoes need a lot of nutrients and you want to provide enough at every stage of their development. In fact, some gardeners will even add a small amount of fertilizer to their seedlings if they start them indoors.

As you plant your tomatoes in your garden, you should add some fertilizer to the soil. However, this needs to be done a bit delicately.

At no point should raw fertilizer touch the roots of your plants as this can cause them to burn. Instead, dig a large hole, place some fertilizer in the bottom, then add a layer of soil, before finally adding your tomato plant. The fertilizer will absorb into the soil and the tomato roots will find the diluted nutrients.

Step 2 – Always use water

Before you add fertilizer, give your tomato plants a good soak. Make sure the soil around the plant is nice and saturated before adding the fertilizer.

This dilutes the fertilizer so that there is less chance of the plant burning. It also forces the plant to take in a less concentrated amount.

Step 3 – Fertilize as fruit grows

Look for tiny tomatoes to start to grow on your plant. This is a sign that your plant is going to require more nutrients to inspire larger growth.

You can add more fertilizer to the soil around your tomatoes but, again, make sure it is well-diluted to promote a slower uptake.

You can fertilize your tomatoes every two to three weeks using this method. Just place the fertilizer on the soil and make sure it doesn’t touch the foliage of the plant.

Step 4 – Stop in the fall

Unlike perennial plants, tomatoes are done growing in the fall, usually around September or October. Once the temperature drops, they are done for.

As your tomatoes ripen, you can stop fertilizing as your plants don’t need many more nutrients to continue. However, as you dig out your tomatoes, you may want to take the opportunity to build up your soil for the next year and add some compost.

When should I apply fertilizer to my tomatoes?

You should first add fertilizer to your tomatoes as you plant them in the ground. Add some fertilizer to the hole where you will place your plants.

Then, wait until your plant starts to grow tomatoes and after this, you can fertilize every two to three weeks.

Can you over-fertilize tomatoes?

Yes, you can definitely over-fertilize your tomatoes. If there is too much nitrogen it can burn the plants and also promote more foliage growth, rather than fruit growth.

What is the best fertilizer to use on tomatoes?

There are two categories of fertilizers you can use and both have their pros and cons.

Organic fertilizer

If you are worried about burning your plants or giving them too much fertilizer at once, then you may want to opt for organic fertilizer. This can include aged manure, compost, or bone meal.

Many gardeners will also add crushed eggshells to their soil as this provides an extra boost of calcium, which tomatoes especially need.

Add the organic matter to your soil, especially when you first plant your tomatoes. Then, as your plants grow, add more of the organic matter by gently working it into the soil.

You can find organic matter from neighboring farms or at your local gardening center. It is all-natural and you don’t have to worry about any chemicals.

However, you won’t know the exact ratio of nutrients in your organic fertilizer, which can leave some people feeling a bit confused.

Inorganic fertilizer

For those that like knowing exact numbers, a pre-made inorganic fertilizer can offer great peace of mind. You can start by measuring the nutrients in your current soil and then matching the fertilizer exactly.

Often, inorganic fertilizers are used when you don’t already have a strong foundation of soil. They are good in an in-between phase but if you are able to constantly add manure and compost to your garden, the soil will naturally build up more nutrients for all your plants.


To grow the best and biggest tomatoes you can, it is essential that you regularly fertilize your tomatoes. Start by adding some to the soil when you first plant your tomatoes and then continue adding some every few weeks once the fruit starts to grow.

Related Articles:

Save for later!

Leave a Comment