Why do tomato fruits develop dark spots or cracks?

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Published: September 28, 2025

Updated: September 28, 2025

Dark spots and cracks occur on tomato fruits due to avoidable situations. Blossom end rot makes leathery black spots at the bottom of the fruit due to calcium deficiencies. Cracking occurs when excessive water follows a drought, causing the skin to split. Both issues are due to inconsistent moisture management in the garden.

Blossom End Rot

Caused by calcium deficiency during fruit development
Triggered by irregular watering patterns
Prevented with consistent moisture and gypsum supplements

Fruit Cracking

Radial splits from rapid water uptake after drought
Concentric rings from heavy dew on ripe fruit
Stopped by gradual watering and harvesting before rain

Tomato Fruit Issue Solutions
Problem	Immediate Action	Long-Term Prevention
Blossom end rot	Remove affected fruits	Apply gypsum, mulch consistently
Radial cracks	Harvest split tomatoes	Water gradually after dry spells
Concentric cracks	Pick before heavy dew	Use rain covers for ripe fruit

Tomato Fruit Issue Solutions

ProblemBlossom end rotImmediate ActionRemove affected fruitsLong-Term Prevention

Apply gypsum, mulch consistently

ProblemRadial cracksImmediate ActionHarvest split tomatoesLong-Term Prevention

Water gradually after dry spells

ProblemConcentric cracksImmediate ActionPick before heavy dewLong-Term Prevention

Use rain covers for ripe fruit

Consistent watering prevents blossom end rot and cracking. Water deeply with 1-1.5 gallons 2-3 times a week. Moisture meters maintain a consistent level. Mulch helps keep even soil moisture. The plant cells rupture, causing splits and decay due to rapid changes.

Prevent blossom end rot with calcium management. Do a soil pH test first, below 6.0, calcium locks up. Apply gypsum at planting for quick absorption. My tomatoes stopped developing spots after I applied gypsum and switched to drip irrigation, which provided even moisture.

Cracking can be minimized through a strategic harvest approach. Harvest tomatoes before an anticipated rainfall or heavy dew, and consider planting crack-resistant varieties such as 'Mountain Fresh' if you live in a humid environment. Also, you can cover clusters that are nearly ripe with breathable row covers during wet periods.

During fruit development, check your plants daily. Blossom end rot can occur in a matter of days, and cracking can happen overnight after a break in the drought. Don't wait to address any issues; this is the way to save a tomato harvest! Healthy practices yield rewards, resulting in perfect tomatoes throughout the entire season.

Read the full article: 8 Common Problems With Tomato Plants and Solutions

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