Problem & Solution

Why Are My Tomato Leaves Turning Yellow? Causes & Fixes

Yellow tomato leaves are most commonly caused by nitrogen deficiency, overwatering, or early blight disease. Check the pattern of yellowing: bottom leaves first usually indicates nitrogen deficiency or natural aging, while random yellow spots suggest disease. Water only when the top inch of soil is dry, and feed with a balanced fertilizer every 2-3 weeks.

Written by SuNutri Editorial Team, Master Gardeners

Signs & Symptoms

•Lower leaves turning yellow first while upper leaves stay green
•Yellow patches between leaf veins (interveinal chlorosis)
•Yellow spots with dark brown centers
•Entire plant turning pale yellow-green
•Wilting despite moist soil

Common Causes

Nitrogen Deficiency

The most common cause of yellow tomato leaves. Nitrogen is mobile in plants, so deficiency shows first in older, lower leaves as the plant moves nitrogen to new growth. Leaves turn uniformly pale yellow starting from the bottom up.

Overwatering

Waterlogged soil prevents roots from absorbing oxygen and nutrients. Leaves turn yellow, plants wilt even in wet soil, and roots may rot. This is especially common in containers without adequate drainage.

Early Blight (Alternaria)

A fungal disease causing dark brown spots with concentric rings (target pattern) surrounded by yellow halos. Starts on lower leaves and progresses upward. Spreads in warm, humid conditions.

Magnesium Deficiency

Causes yellow areas between leaf veins while veins stay green (interveinal chlorosis). Common in acidic soils or when excess potassium blocks magnesium uptake.

Natural Leaf Senescence

Some yellowing of lower leaves is normal as the plant matures and directs energy to fruit production. If only a few bottom leaves are affected and upper growth looks healthy, this is natural.

Solutions

For Nitrogen DeficiencyImprovement visible within 1-2 weeks

1.Apply a balanced fertilizer (10-10-10) or one higher in nitrogen
2.For organic options, use blood meal, fish emulsion, or compost tea
3.Water in the fertilizer thoroughly
4.Repeat feeding every 2-3 weeks during growing season
5.Mulch with compost to provide slow-release nitrogen

For OverwateringRecovery begins within 1 week if roots are not damaged

1.Stop watering until top 1-2 inches of soil is dry
2.Improve drainage by adding perlite or coarse sand to soil
3.Ensure containers have adequate drainage holes
4.Water deeply but infrequently (1-2 inches per week total)
5.Consider raised beds if soil is heavy clay

For Early BlightFungicide stops spread within 1-2 weeks; damaged leaves will not recover

1.Remove and destroy affected leaves immediately
2.Apply copper fungicide or Bacillus-based organic fungicide
3.Improve air circulation by pruning lower branches
4.Water at soil level to keep leaves dry
5.Apply mulch to prevent soil splash onto leaves

For Magnesium DeficiencyFoliar spray shows results within 3-5 days

1.Dissolve 1 tablespoon Epsom salt in 1 gallon water
2.Apply as foliar spray or soil drench
3.Repeat every 2 weeks until symptoms improve
4.Test soil pH and adjust to 6.0-6.8 if needed
5.Add dolomitic lime to provide long-term magnesium

Prevention Tips

Test soil before planting and amend based on results
Rotate tomatoes to different beds each year
Space plants 2-3 feet apart for good air circulation
Water consistently at soil level using drip irrigation
Apply mulch to regulate moisture and prevent disease splash
Feed regularly with balanced fertilizer throughout growing season
Remove lower leaves that touch the ground

Commonly Affected Plants

Beefsteak Tomatoes Cherry Tomatoes Roma Tomatoes

Frequently Asked Questions

Should I remove yellow leaves from my tomato plant?

Yes, remove severely yellowed leaves, especially if they show signs of disease. This improves air circulation and prevents disease spread. However, leave mildly yellowed leaves if the plant is stressed, as they still provide some energy through photosynthesis.

Can yellow tomato leaves turn green again?

Mildly yellowed leaves may recover some green color if the underlying cause is corrected quickly. However, severely yellowed or damaged leaves will not fully recover and should be removed so the plant can focus energy on new healthy growth.

How often should I fertilize tomatoes to prevent yellow leaves?

Feed tomatoes every 2-3 weeks with a balanced fertilizer once they start flowering. Use a fertilizer with slightly higher phosphorus (like 5-10-10) during fruiting. Avoid over-fertilizing with nitrogen, which causes excessive foliage at the expense of fruit.

Is it normal for tomato leaves to turn yellow in fall?

Yes, as the growing season ends and temperatures drop, tomato plants naturally begin to die back. Yellow leaves in late season combined with slowing fruit production is normal senescence, not a problem to fix.