How to Choose the Best Fertilizer for Your Tomato Plants

Your tomato plant’s growth stage will largely determine how you should fertilize it. Tomato seeds do not need fertilization to germinate, so as long as you have a healthy, balanced soil to begin with, your tomato seedlings should sprout. Once the tomato plant starts to set fruit, you can lightly fertilize the garden soil surrounding the area every 10 to 14 days.

Determining the best fertilizer for your tomatoes depends on your soil composition and the ratio of its nitrogen, phosphorus, and potassium (N-P-K) elements. Perform a soil test to figure out which specific nutrient your soil lacks to help you choose the best tomato fertilizer for your vegetable garden.

If your soil is well-balanced or slightly higher in nitrogen, choose a fertilizer that is higher in phosphorus and lower in nitrogen, like a 5-10-5 ratio. Conversely, if your soil is low in nitrogen, use a more balanced fertilizer, like a 10-10-10. Be mindful of your nitrogen content, however, as too much nitrogen inhibits fruit production.

You can use an organic fertilizer like fish emulsion, which is high in all three N-P-K elements, as well as sulfur, magnesium, and calcium, which can help prevent blossom end rot. Sometimes you only need to boost a specific element: For instance, bone meal is specifically high in phosphorus, where Epsom salts are only used to add magnesium and sulfur to deficient soil.

When fertilizing tomatoes while transplanting, mix fertilizer with the soil and place the blend at the bottom of the planting hole, as straight fertilizer will burn your tomato plant’s roots. For fertilizing after fruiting, water well before spreading the fertilizer, and then place the organic matter about six inches away from the plant’s base (to prevent burning).

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