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Nutrient Deficiency in Tomato Plants: Symptoms, Causes & How to Fix Them

Nutrient deficiency in tomato plants is one of the most common reasons for poor growth, yellowing leaves, low yields, and misshapen fruit. Tomatoes are fast-growing, heavy-feeding plants, and even short-term nutrient imbalances can quickly show up as visible deficiency symptoms.

Tomato nutrient deficiencies are often misdiagnosed as pests or disease. In reality, most problems come down to missing nutrients, poor uptake, or nutrient competition in the soil. Learning how to identify tomato deficiency symptoms early allows you to correct the issue before yield and fruit quality are affected.

How to Identify Nutrient Deficiency in Tomato Plants

The position of symptoms on the plant is one of the most important clues:

Older leaves affected first: Nitrogen, magnesium, potassium deficiencies
New growth affected first: Calcium, iron, zinc deficiencies
Leaf colour changes: Yellowing, purpling, dark patches, or interveinal chlorosis
Fruit symptoms: Poor size, cracking, rot, or uneven ripening

Understanding whether symptoms appear on old or new growth helps narrow down the exact tomato plant nutrient deficiency quickly and accurately.

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Common Nutrient Deficiencies in Tomato Plants

Nitrogen Deficiency in Tomato Plants

Nitrogen deficiency in tomato plants causes general pale growth and slow development. It usually appears on older leaves first.

Older leaves turn pale green to yellow
Overall plant growth slows
Thin stems and small leaves

Nitrogen deficiency in tomatoes is common in poor soils or when nutrients have been leached by heavy watering. It can also occur late in the season when plants have exhausted available nitrogen.

Phosphorus Deficiency in Tomato Plants

Phosphorus deficiency in tomato plants affects root development and early growth, often showing up in cool or compacted soils.

Dark green or purplish leaves
Leaf undersides may turn purple
Slow root growth and delayed flowering
Leaves may develop dark or black patches in severe cases

Phosphorus deficiency in tomato leaves turning black is often linked to cold soil temperatures that restrict uptake, even when phosphorus is present.

Potassium Deficiency in Tomato Plants

Potassium deficiency in tomatoes affects fruit quality, disease resistance, and water regulation.

Yellowing or browning leaf edges
Leaf margins scorch or curl
Poor fruit size and uneven ripening

Potassium deficiency in tomato plants often becomes more obvious during flowering and fruiting, when potassium demand increases sharply.

Iron Deficiency in Tomato Plants

Iron deficiency in tomato plants appears on new growth first and is common in alkaline or heavily limed soils.

Young leaves turn yellow while veins remain green
New growth appears pale and weak
Severe cases cause leaf whitening

Tomato iron deficiency is usually an uptake issue rather than a true lack of iron in the soil.

Zinc Deficiency in Tomato Plants

Zinc deficiency in tomato plants affects growth hormones and leaf development.

Small, narrow leaves
Shortened internodes
Distorted new growth

Zinc deficiency is less common but can occur in high-phosphorus soils or where trace elements are missing.

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How to Fix Nutrient Deficiency in Tomato Plants

Fixing nutrient deficiency in tomatoes requires more than just adding fertiliser. The goal is to restore balance and ensure nutrients are actually taken up by the roots.

Step 1: Use a Balanced Base Fertiliser

A complete fertiliser ensures nitrogen, phosphorus, potassium, and trace elements are supplied together, preventing new deficiencies from developing.

Step 2: Correct Calcium and Magnesium Imbalances

Many tomato deficiencies are linked to nutrient competition. Calcium and magnesium imbalances are particularly common during flowering and fruiting.

cal mag fertiliser helps stabilise calcium and magnesium levels, improving nutrient uptake and reducing recurring deficiency symptoms.

Step 3: Adjust Feeding for Fruiting Stage

As tomatoes begin to flower and set fruit, nutrient demand shifts. Supporting fruit development without overdriving leafy growth is critical.

tomato fertiliser for flowering and fruiting is ideal during this stage, supporting fruit quality while maintaining nutrient balance.

Related Tomato Guides

Final Recommendation

Nutrient deficiency in tomato plants is best managed through balanced feeding, consistent watering, and correcting nutrient competition early. Using a complete fertiliser as a foundation, supported by calcium and magnesium where needed, prevents most tomato deficiency problems before they impact yield or fruit quality.