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 Transplanting
It 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.