Ideal applications are made in the morning hours when temperatures are below 85 degrees F. Buy Hi-Yield 3.25# Ammonium Calcium Nitrate Ammonium calcium nitrate. The granular fertilizer comes in a 3., 5 lb., bag. Bonide Rot-Stop Tomato Blossom End Rot, 32 oz Ready-to-Use Spray Garden Fertilizer for Calcium Deficiency 167 - The Home Depot The plant food provides calcium and nitrogen to aid in growth and protect against deficiencies. Hi-Yield (32128) Ammonium Calcium Nitrate 15-0-0, Helps Precent Blossom End Rot in Tomatoes (3., 25 lbs., ) Calcium Ammonium Nitrate - China Calcium Ammonium Nitrate Manufacturers... This is an A to Z guide to identify, control, and prevent blossom end rot on tomato plants. Learn the symptoms, causes, and solutions to this common problem in the tomato garden. Get specific information on how to prevent blossom end rot, including soil testing techniques and the best varieties of tomato plants to grow