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The blossom end of a pepper is the end that is opposite the one that was attached to the plant's stem or branch.
Blossom end rot is when the blossom end of the plant begins to darken in a small area. It is tan in color and begins to get bigger. The tissues in the affected area are shrunken or shriveled and look like dry leather.
Lack of Calcium
The rot comes from a lack of calcium in the pepper, which can be caused by a lack of calcium in the soil. Adding lime to the soil or spraying the plants with anhydrous calcium chloride can prevent this.
If the water supply fluctuates too much, it can also cause blossom end rot. Planting the chili peppers in deep, well-drained soil and using mulch around the plants can prevent this.
Be careful with your use of fertilize, because too much fertilizer can also cause blossom end rot. This is especially true when using nitrogen.
Read more: Blossom End Rot in Capsicum | eHow.com http://www.ehow.com/facts_5896050_blossom-end-rot-capsicum.html#ixzz0sChIHXDs