Food Gardening Network

Growing Good Food at Home

Should You Fertilize Tomato Plants?

Fertilizer pellets added to soil around tomato seedling

Tomatoes need lots of nutrients to properly grow, and fertilizers can provide the extra nutrients that tomatoes need to grow quickly and fully.

The use of tomato fertilizer depends on the current nutrient content of your soil. To be certain, the best thing is to have your soil tested. If your soil is correctly balanced or high in nitrogen, you should use a fertilizer that is slightly lower in nitrogen and higher in phosphorus, such as a 5-10-5 or a 5-10-10 mixed fertilizer. If your soil is lacking in nitrogen, use a balanced fertilizer like 8-8-8 or 10-10-10. If you can’t get a soil test, just go ahead and use higher phosphorus tomato plant fertilizer—unless you’ve experienced past problems with sickly tomato plants.

Too much nitrogen will give you lush, green tomato plants, but very little fruit. Using straight-up phosphorus, and not a complete, mixed fertilizer, can solve this problem by minimizing the effects of too much nitrogen in the soil.

Fertilize your tomatoes when you first plant them by mixing the tomato-plant fertilizer in with the soil at the bottom of the planting hole. Then place some unfertilized soil on top before placing the tomato plant into the planting hole. If raw fertilizer has direct contact with the plant roots, it can burn the tomato plant.

As soon as your tomato plants start bearing fruit, you can fertilize again right after watering the plants well. Failure to water the plants first can cause the plants to absorb too much fertilizer all at once and burn them. When fertilizing, stay at least 6 inches away from the base of the plant—fertilizer running off onto the stem can also burn your tomato plants.

Add light amounts of fertilizer every one to two weeks during the growing season until the first frost kills your plants.

Do you fertilize your tomato plants? What type of fertilizer do you use? How often do you fertilize? Please tell us exactly how and when you fertilize your tomato plants.


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