Posted by: ssorrrell | July 8, 2007

Blossom End Rot

A few tomatoes have gotten blossom end rot lately. This is caused by calcium deficiency in fast growing parts of the plant like fruit. It doesn’t seem to be a disease and only a small quantity of the fruit has been affected. This morning I baked 10 egg shells, crushed them, and put them under the biggest plants. I have some 2 month weathered charcoal ash I’ll spread under them and water tonight.

90% of the calcium in a mature fruit gets there when it is thumbnail size. Due to their increased transporation (sweating) leaves get far more calcium than fruit. 4

Peppers, watermelon, squash, and eggplant can be affected.

Recommended Treatments
Lime Soil to ~6.5 pH
Apply lime months before planting
Some say leaf sprays of calcium nitrate or calcium chloride work and some say they don’t
* Calcium chloride can damage leaves in excess
* Spray when it’s cool
Keep soil moisture even and the right amount
Water the right distance from the plant to reach feeder roots
Use low nitrogen super phosphate fertilizer
Remove affected fruit
Don’t treat the problem as it may be temporary


  1. The Ohio State University Fact Sheet
  2. North Carolina State University
  3. Cornell University
  4. University of Georgia College of Agricultural & Environmental Sciences
  5. Veggie Garden Tips


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