Tomatoes need consistent watering more than heavy watering

Blossom end rot — the black bottom on tomatoes — is caused by inconsistent calcium uptake, which is caused by inconsistent watering. The calcium is in the soil; the problem is delivery. Water deeply every 2-3 days rather than lightly every day. Mulch 3 inches deep to maintain soil moisture. Adding calcium supplements is almost never the fix — consistent soil moisture is.