Calcium is the plant nutrient most likely to be unavailable to roots when needed. An essential nutrient itself, calcium also improves root uptake of other plant nutrients, especially ammonium nitrogen. Calcium does not move from old to new plant tissues, so a constant supply of soluble calcium is needed. The growing points of both roots and shoots are sensitive to insufficient calcium, but roots more so. The ratio of calcium to sodium is more critical than the actual concentration of calcium.
Tip burn on young leaves of celery, lettuce and cabbage.
Death of terminal buds and root tips. Abnormal dark green appearance of leaves. Premature shedding of blossoms and buds. These regions receive in excess of 40 inches of rainfall each year. Deficiency symptoms, such as tomato blossom end rot, often appear there after a period of heavy rainfall.