Problem & Solution

How to Fix Blossom End Rot on Tomatoes & Peppers

Blossom end rot is caused by inconsistent watering that prevents calcium from reaching developing fruit, not by lack of calcium in soil. The solution is maintaining even soil moisture through consistent watering and mulching. Affected fruits cannot be saved but the plant will produce healthy fruit once watering is corrected.

Written by SuNutri Editorial Team, Master Gardeners

Signs & Symptoms

•Dark, sunken, leathery patch on the bottom (blossom end) of fruit
•Affected area starts water-soaked, then turns brown to black
•First fruits of the season most commonly affected
•Can affect tomatoes, peppers, eggplants, squash, and melons
•Rot may be small spot or cover half the fruit

Common Causes

Inconsistent Watering

The primary cause of blossom end rot. When soil moisture fluctuates between too wet and too dry, plants cannot transport calcium to rapidly growing fruit even when calcium is present in soil. This is especially common during hot, dry periods.

Rapid Plant Growth

Fast-growing plants during warm weather demand more calcium than roots can supply. First fruits often show blossom end rot while later fruits develop normally once growth slows.

Root Damage

Damaged roots from cultivation, transplant shock, or root rot cannot absorb and transport calcium effectively. Avoid cultivating near tomato plants.

Excess Nitrogen

Too much nitrogen fertilizer causes rapid leaf growth that competes with fruit for calcium. Lush, dark green foliage with blossom end rot suggests over-fertilization.

Extreme Soil pH

Very acidic (below 6.0) or alkaline (above 7.0) soil can lock up calcium, making it unavailable to plants. Optimal pH for calcium availability is 6.2-6.8.

Solutions

Correct Watering ImmediatelyNew fruit should be healthy within 1-2 weeks

1.Water deeply and consistently - 1 to 2 inches per week
2.Check soil moisture daily during hot weather
3.Water when top inch of soil feels dry
4.Use drip irrigation or soaker hoses for even moisture
5.Water in morning so plants are hydrated before midday heat

Apply MulchImmediate benefit for moisture retention

1.Apply 2-4 inches of organic mulch around plants
2.Use straw, shredded leaves, or wood chips
3.Keep mulch 2 inches away from stems
4.Replenish mulch as it decomposes
5.Mulch regulates soil moisture and temperature

Calcium Foliar Spray (Temporary)May help currently developing fruit

1.Mix calcium chloride spray according to package directions
2.Apply directly to developing fruit and leaves
3.Spray in early morning or evening to avoid leaf burn
4.Repeat weekly during fruiting
5.Note: This treats symptoms but does not address root cause

Adjust FertilizationImprovement in subsequent fruit set

1.Stop or reduce nitrogen fertilizer if plants have lush growth
2.Switch to low-nitrogen, higher-calcium fertilizer
3.Avoid high-nitrogen fertilizers like fresh manure
4.Add gypsum to provide calcium without changing pH
5.Use balanced tomato-specific fertilizers

Prevention Tips

Install drip irrigation or soaker hoses before planting
Apply thick mulch layer immediately after transplanting
Choose blossom end rot-resistant varieties when available
Avoid over-fertilizing, especially with nitrogen
Test soil pH and maintain between 6.2 and 6.8
Add calcium sources like crusite lime or gypsum before planting
Avoid cultivating or disturbing soil near plant roots

Commonly Affected Plants

Beefsteak Tomatoes Roma Tomatoes Bell Peppers Jalapeño Zucchini

Frequently Asked Questions

Can I eat tomatoes with blossom end rot?

Yes, you can eat the unaffected part of the tomato. Simply cut away the damaged bottom portion. The rest of the tomato is safe and nutritious. However, the damaged area may allow secondary rot to enter, so use affected tomatoes quickly.

Will adding eggshells prevent blossom end rot?

Eggshells are not an effective treatment. They decompose too slowly to provide calcium during the growing season. Blossom end rot is usually a water-transport issue, not a calcium deficiency in soil. Focus on consistent watering instead.

Why do my first tomatoes get blossom end rot but later ones are fine?

Early fruits develop during rapid plant growth when calcium demand is highest. As the plant matures and growth slows, calcium transport catches up with demand. Consistent watering from the start helps prevent this early-season problem.

Does Epsom salt help with blossom end rot?

No, Epsom salt (magnesium sulfate) does not help and may worsen the problem. Excess magnesium competes with calcium uptake. Unless your soil test shows magnesium deficiency, avoid Epsom salt when dealing with blossom end rot.