What fertilizer nutrient balance to choose for tomatoes

Nitrogen. Nitrogen encourages leaf growth, which is why fertilizers with higher ratio of nitrogen (the first of the three numbers) are an optimum choice for lawns and grasses. But in tomatoes, excess leaf growth discourages blossoms and fruit.

A complete fertilizer with a balanced supply of the three major nutrients, such as 10-10-10 or 5-10-10, is a better choice for tomato plants at initial planting time. Stay away from high-nitrogen fertilizers such as urea, ammonium sulfate or fresh manure, which will help produce dark green, tall tomato plants but fewer tomatoes.
 

Phosphorus. Phosphorus (the second number in the N-P-K ratio) encourages flowering, and therefore fruiting.

Potassium. Once a tomato plant starts flowering, it needs a higher ratio of potassium (the third number in the N-P-K ratio). Good organic sources of potassium are granite dust and wood ash.

Specialized tomato fertilizer

Two fertilizers specially formulated for tomatoes are

• Miracle Gro Tomatoes (18-18-21): a crystal formula that is mixed with water and applied through a hose, sprayer, or sprinkler
• Tomato Tone (4-7-10): a granular fertilizer that is worked into the soil. Tomato Tone is organic and contains calcium, magnesium, sulfur and trace nutrients.

When to add nutrients during the tomato season

Once a plant is established in the garden, a phosphate-concentrated application (such as 0-46-0 commercial fertilizer) every 6-8 weeks increases tomato production. Bone meal, with an analysis of 4-12-0, is a good organic source of phosphorus. When a tomato plant sets fruit, start a systematic fertilization program and feed every three weeks until frost.
 

When To Use Tomato Plant Fertilizers

Tomatoes should be first fertilized when you plant them in the garden. You can then wait until they set fruit to start fertilizing again. After the tomato plants start growing fruit, you can add light fertilizer once every one to two weeks until the first frost kills the plant.

How To Fertilize Tomatoes

When fertilizing tomatoes while planting, mix the tomato plant fertilizer in with the soil at the bottom on the planting hole. Then place some unfertilized soil on top of this before placing the tomato plant into the hole. If the raw fertilizer comes in contact with the roots of the plant, this can burn the tomato plant.

When fertilizing tomato plants after the fruit have set, first make sure that the tomato plant is watered well. If the tomato plant is not watered well before being fertilized, it can take up too much fertilizer and burn the plant.

After watering, spread the fertilizer on the ground starting approximately 6 inches from the base of the plant. Fertilizing too close to the tomato plant can result in fertilizer running off onto the stem and burning the tomato plant.