When to Fertilize Tomato Plants

When to Fertilize Tomato Plants

When to fertilize tomato plants is one of the most commonly asked questions that I generally come across.

There are many different philosophies on how and when to actually fertilize tomato plants, and there really isn’t a wrong answer. It all depend on works well for your specific region and application.

The only way to really be wrong at fertilizing tomato plants is over-fertilizing, or supplying too much of the wrong kinds of nutrients.

It’s important to remember that fertilizing too much can be more harmful at times than not fertilizing at all. In fact, I’d recommend not fertilizing at all if you have any doubts.

Since I covered how to fertilize tomato plants in a previous article, I thought it would be a great time to discuss when to fertilize tomato plants.

When to Fertilize Tomato Plants

Everyone has a different system for fertilizing their tomato plants, and if you ask one hundred tomato gardeners their method you would probably get one hundred different combinations.

Here are the methods I use for knowing when to fertilize tomato plants:

When Transplanting Tomato Seedlings

Tomato Plants May Need Fertilization Two or Three Weeks After TransplantingIt is a good idea to add a handful of organic tomato fertilizer at the bottom of the hole when transplanting tomato seedlings into the vegetable garden.

Just sprinkle the handful into the hole and mix with soil and compost.

You can also have the soil/compost/organic fertilizer already pre-mixed and use that to fill the hole as you are planting. Make sure to water the tomato plant well to incorporate all the ingredients well to give the seedling a good start.

If you sowed the tomato seeds directly in the vegetable garden, wait until the plants are about eight inches tall, and sprinkle about 1/4 cup of granular organic fertilizer around each plant, then water in well.

You can also use liquid fertilizers like fish emulsion, seaweed extract, kelp extract, or compost tea.

Two to Three Weeks After Transplanting

After two to three weeks the tomato plants should be established and getting taller.

At this point sprinkle another handful of granular organic fertilizer around each tomato plant and water it in well.

When Tomato Plants Begin Setting Fruit

Your tomato plants will begin developing blossoms which will begin setting fruit when conditions are right.

The tomato plants may need a boost of nutrients when they begin setting fruit.

Sprinkle a handful of granular organic fertilizer around each plant and water in well.

That’s It!

That is all the fertilization that is really needed for tomato plants. The key to this whole process is having soil that is well-amended with organic matter (like compost, rabbit droppings, worm castings, leaf mold, etc.) to begin with.

If you begin with rich soil, fertilization is not needed as much, if at all.

If you do add fertilizer to your tomatoes, I recommend:

Tomato-tone Organic Tomato Fertilizer

Gardener's Supply Tomato Fertilizer

Burpee's Organic Tomato Fertilizer

Tomatoes Alive! by Garden's Alive!

I have used all of these with great results, and they are all composed from organic ingredients.

You can also use liquid fertilizers such as fish emulsion, seaweed extract, kelp extract, or compost tea as a weekly feeding for your tomatoes.

Discuss in our forums

9 Comments on When to Fertilize Tomato Plants


    • Hi Jack – It may not hurt to add a little fertilizer to your plants. You can also add worm castings or compost.

      So, to answer your question – yes. You can fertilize them. Good luck! 🙂

  2. I am growing tomatoes in two pots (1) Stupice and (2) Tumbling Tom. They were transported to the pots 2 weeks ago (from seedlings) and are starting to grow and blossom’s are forming. As far as fertilizing, I have tomato tone AND fish emulsion fertilizer – which is better to use? How much should I use for 6 gallon containers? I am also growing some hot peppers in another container (2 different varieties) – How much fertilizer and what kind? Thank you!

  3. Hello…I wrote you a previous & separate email asking you about using chlorinated Tap water to water tomato plants after using Tomato Tone…The Espoma Co. told me “no problem”… They said it wouldn’t kill the microbes, etc… Hope you got my previous email about this & will respond to my questions…. Thanks….. H. Sher

    • Hello H.,

      Thank you for the very interesting comment! I appreciate you contacting Espoma and getting their advice on using tap water with their fertilizer. It’s good to know what the manufacturer advises when using their product.

      Yes, I received your email and will be answering it soon!

  4. Hello,my tom. plants are starting to produce , but my plants don’t have a dark green color. I planted in straw bales . Is it time to put fish emulsion down or leave them alone. Thanks ,Greg

    • Hi Greg – Sure, you can use fish emulsion at any time. I have a plant planted in a container that began to turn yellow and was a pale green. I watered it with diluted fish emulsion once a day for 10 days and it turn a very deep green and produce three more clusters of blooms. It’s really some good stuff!

  5. Hi I just want to know about planting in a straw bale…why would I want to do that & how?
    Thanks, I appreciate your helpful ideas for using 2 liter bottles to water tomatoes.

  6. Getting ready to plant a late garden due to seller. My first row will be tomatos and the row will be 100 ft long. I plan on trans planting my plants that I started today into this area as soon as I take possession of the property in August anything I should do special to make this late crop happen??

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