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How To Fertilize Tomato Plants For Success! The Simple Secrets To A Big Harvest

This week’s podcast and corresponding article are all about how to best fertilize your tomato plants, including when to fertilize, how often, and a look at some of the best fertilizing methods to use.

Tomatoes are big feeders from the soil. Not only are they heavy feeders of nitrogen, but they also require potassium, phosphorous, calcium, and a slew of other trace nutrients as well. And that is exactly why it’s so important to supply them extra nutrients throughout their growing cycle!

You can listen in below to our complete podcast on the fertilizing tomatoes, or read on for our full-length article on the subject. As always, we have included all of the podcast resource links at the end of this article.

How To Fertilize Tomato Plants For Success

#1 Fertilizing Starts Right At Planting

Although many think of fertilizing tomato plants once they are planted in the ground, you should really fertilize your plants right as you plant them. This allows the plants the nutrients they need to establish in the soil early.

But for this fertilizing application, you are not using a granular or liquid fertilizer, but a few organic materials that can provide slow and steady power for your young transplants. We use a combination of the four materials below to power up our plants at planting time:

  • Compost – A cup or two in every planting hole provides the perfect “slow-release” set of nutrients for young tomato plants
  • Egg shells – a few crushed egg shells (we like to pulverize ours) will provide calcium to the tomato plant for healthier fruit setting. Calcium helps prevent blossom end rot, a leading issue for tomato plants.
  • Worm castings – ¼ to one-half cup in every planting hole. Like compost, an excellent slow-release fertilizer that tomato plants love!
  • Coffee grounds – a couple of teaspoons per planting hole. Coffee grounds add nitrogen and other trace minerals to the soil at planting time. They also help retain moisture to the tomato plant’s roots.

Once planted, apply a few inches of compost around the base of your plants as a mulch. Extend the compost ring out about 8 inches in diameter. This will act as a slow release fertilizer every time it rains or you water.

fertilize tomato plants
Getting your tomatoes off to a great start means supplying your planting holes with power.

Fertilizing After Planting – How To Fertilize Tomato Plants

When should you start fertilizing transplants?

  • Allow the plants to acclimate and establish.
  • Wait usually a week to ten days before starting to fertilize.
  • Can depend on weather, condition of the plant, etc.

Plants need a bit of time to acclimate to the soil and establish their roots before fertilizing. If you fertilize as soon as you plant, it can actually shock the plants and injure or stunt them. It is usually best to wait at least a week to ten days before applying your first dose.

The Best Way To Fertilize Tomato Plants

There are two basic types of fertilizers that you can use on all vegetable plants, including tomatoes. Those two types are granular fertilizer and liquid fertilizer.

Both certainly have their uses and can be quite effective. Granular fertilizers are applied topically or in the soil, and slowly break down to release their power. Liquid fertilizers on the other hand are usually water based, and feed more quickly, both through the roots and soil, and by absorbing through the leaves and stems.

Why Liquid Fertilizing Is Best For Tomatoes

When it comes to tomato plants, liquid fertilizing is one of the best options because it delivers an easy-to-absorb set of nutrients quickly to the plant. It also has the advantage of being able to be used as a normal part of your watering of the plants.

As for the best types of liquid fertilizers to use, there are a whole slew of great, all-natural liquid fertilizer options on the market. (See our reference list at the end of the article) Some, like Espoma Tomato Liquid Plant Food, are even created with specifically powering tomatoes in mind.

They all can work well, but our liquid fertilizer of choice is and will always be compost tea. Not only is it 100 percent natural and organic, it’s easy to make and apply. In addition, if you have your own compost on hand, it’s completely free. (Worm casting tea is also a great option)

Compost tea will not overpower plants , but gives them a steady and balanced dose of nutrients. Even better, however, is that compost tea can be a part of your watering routine, giving the plants moisture and nutrients all at the same time.

Question Of The WeekHow To Fertilize Tomato Plants

This week’s question of the week is from Deena from Charleston South Carolina : “How do you make your compost tea? I heard that you have to use an aerator or water pump or it can be dangerous for your plants?

Answer: You will find this information many times around the web, but the simple truth is, you can make an effective compost tea simply by steeping compost in a 5 gallon bucket full of water. Simply stir the water once or twice a day, and in a week, you will be ready to go!

To make worm casting tea, mix a 3/4 to 1 cup of castings with 1 to 2 gallons of water. Steep for 24 hours, strain and water plants with the liquid.

How Often To Fertilize Tomato Plants

  • Better to be consistent with lower doses than with a large single dose
  • The issues with too much fertilizer – too much foliage, no blooms
  • For best results, fertilize every two weeks after the plants have established in the soil. If you are using a commercial liquid fertilizer, use at half-strength for a low and slow approach. Compost tea and or worm casting tea will naturally be at a lower dose.
  • Fertilize until you begin to see the tomatoes form and begin to turn, and then stop fertilizing.

You will not need to fertilize determinate tomatoes after this period. These varieties bear all of their fruit at once, and then they will die off. For indeterminate varieties, you can continue to fertilize once a month after they begin to bear fruit.

How Much To Fertilize

We use about 1/8 of a gallon per plant for small transplants at first. As they continue to grow and develop, we increase the amount per plant to 1/4 – 1/3 of a gallon for each tomato plant.

To apply, use about a third of your dose to water the foliage, and pour the rest around the root zone of each plant. Again, the beauty of liquid fertilizing is the plant will absorb both through its roots in soil, and through foliar action via its leaves.


  • Fertilize with natural ingredients in the planting hole at planting time.
  • Fertilize with compost ring mulch above the soil.
  • Allow plants to establish before using liquid fertilizer.
  • Fertilize every two weeks but in lower doses.
  • Know when to stop fertilizing – determinate vs indeterminate.


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