Fertilizer for Tomatoes, Peppers, and Eggplants

close-up of blooming chili peppers in the vegetable garden
cherry tomatoes in pots

Summer fruiting crops such as tomatoes, peppers, and eggplants will benefit from a side-dressing of organic fertilizer when they first set fruit and every 4 to 6 weeks thereafter. An alternative is to water in a dilute solution of fish emulsion, seaweed extract, or kelp meal every 10 days.

Feed fruiting crops that have flowered and set fruit with liquid balanced fertilizers such as compost tea, comfrey tea, or solid organic fertilizers in powder, pellet, or granular form. An ideal fertilizer ratio for fruiting tomatoes, peppers, and eggplants is 5-10-10 with trace amounts of magnesium and calcium added.

Liquid organic fertilizers can be watered in around the base of plants or applied directly to crop leaves as foliar feeds. Solid fertilizers can be applied as a top dressing or band of fertilizer around the base of each plant; solid fertilizers should be scratched into the soil with a garden fork or trowel.

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Amount of Fertilizer

If a manure fertilizer was added to the soil just before planting, reduce the fertilizer rate by one-half. Manures are generally high in nitrogen. A balanced fertilizer contains equal or near equal parts nitrogen, phosphorus, and potassium.

When using a commercial organic or non-organic fertilizer, always follow the label directions on the package. Too much fertilizer will be more harmful to plants than not enough. When in doubt, cut the recommended application of fertilizer in half, check the reaction of the plants in 10 days, and then apply the second half of the fertilizer if the plants are doing okay.

For higher yields of fruiting crops such as tomatoes and peppers, extra phosphorus and potassium should be given after flowering and fruiting. To increase the flowering of tomatoes, peppers, and eggplants, give the plants an Epsom salt solution–1 tablespoon mixed with a gallon of water.

For higher yields of leafy crops and crops that have overwintered in the soil such as autumn-planted onions, a top dressing of nitrogen-rich fertilizer will act as a crop booster.

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Fertilizer Timing

It usually takes 10 to 12 weeks from the time transplants are set in the garden for tomatoes, peppers, and eggplants to ripen their first fruit. Fertilize these crops with a side-dressing, for one month, and then again two months after transplanting—as a guide.

Foliar Feeding

Vegetables can take a limited amount of nutrients in through their leaves; this is called foliar feeding. Use a watering can with a fine rose and foliar feed with compost tea, comfrey tea, or seaweed extracts.

Foliar feeding is particularly helpful as a boost or tonic for plants that are lagging or off to a slow start. Foliar feeding commonly results in plants gaining a deep green, healthy look soon after feeding.

Dry fertilizers are generally watered in after they are applied as a side dressing. Foliar feeding does not require watering of the soil before or after applying fertilizer. Foliar feed when the soil is already moist or when the weather is particularly dry and plants can use both a watering and fertilizer application.

Click on these other article titles for more information:

Fertilizer Side-dressing Vegetable Crops

Organic Fertilizers and Soil Amendments

Vegetable Plant Nutrients: Sources and Deficiencies

How to Make Compost Tea

How to Make Comfrey Tea

Written by Stephen Albert

Stephen Albert is a horticulturist, master gardener, and certified nurseryman who has taught at the University of California for more than 25 years. He holds graduate degrees from the University of California and the University of Iowa. His books include Vegetable Garden Grower’s Guide, Vegetable Garden Almanac & Planner, Tomato Grower’s Answer Book, and Kitchen Garden Grower’s Guide. His Vegetable Garden Grower’s Masterclass is available online. has more than 10 million visitors each year.

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