1 Get moisture meter (home depot or----)
2 water early AM
3 soaker hose
4 wheat straw
Any mulch is better than none-- high nitrogen and a lot of rain causes most BER. Just my experience. Good Luck Bill

I think BER (blossom end rot) is more a matter of calcium deficiency than anything.

In general, you'll find that as your maters go to fruit, they'll need more and more water. I top-water (dribble water at the stem base) mine early in the morning and just about sunset daily. I've found if I miss, the plants show it immediately.

OP said "Everybody says that BER is caused by improper watering. However, I've never heard anyone give an explanation of what the PROPER watering techniques are."

Proper watering maintains even soil moisture.

Improper watering is when one allows the soil to go dry, sometimes too dry, hurries up and waters, then breathes a sigh of relief.

In other words, uneven moisture level in the soil.

Then it was said "I think BER (blossom end rot) is more a matter of calcium deficiency than anything."

Sort of.

The shortage occurs when the soil is too dry. The calcium in the soil isn't transported to the blossom end of the tomato.

And I think BER is partially if not wholly a function of tomato genetics (ever wonder why most Romas develop it so frequently and cherries almost never?), which needs several conditions to express itself. Stable soil temps and moisture seem to provide the best environment so that it doesn't occur or occurs only occasionally. I've personally found that deep mulches also help keep the soil temps and moisture stable and BER just doesn't show up very often on the tomatoes I grow. But if they develop it and continue to have it during an entire season, I just don't grow that tomato again. Only one tomato, Park's Whopper hybrid, has done this in my Southern garden, though it did fine when I lived in NJ.

From TOMATO FRUIT RESISTANCE TO BLOSSOM END ROT CONTROLLED BY DOMINANT MONOGENIC FACTOR: Abstract:
A selected tomato line RB-1-79 having stable resistance to blossom end rot of fruits was found out. Segregation studies on F2 and backcrosses showed that the resistance to the disease was determined by one pair of highly effective dominant genes. According to the Tomato Genetic Nomenclature a new gene was designated as BER.

The identified gene is described as giving tomato plants resistance to the condition rather than identifying what gene causes BER. Of course other vegetables also develop BER, so they probably don't have genetic resistance to the condition either.

Peat moss is not a good mulch. It becomes "water phobic" meaning once it dries out it's almost impossible to get wet again in a garden setting. Nearly anything else would be better. Shredded leaves, grass clippings, bark mulch, or compost are better choices.

Keeping the soil moist to a depth of at least 6" (deeper is better) is one of the keys to preventing or minimizing BER. That means a deep watering once or twice a week. The very top can dry out but the root zone needs constant moisture. That doesn't mean sopping wet and muddy, just moist. Muddy for awhile after a rain is ok but roots need air as well as the water and sloppy wet soil blocks air. Nutrients aren't available to the plant if the soil is dry so the calcium present in the soil can't be taken up. BER usually occurs in the first set of fruit but declines later in the season. The temperature swings in spring affect it some, too, but there's not a lot you can do about that except protect the plants if it gets really cold at night.

Time of day for watering depends on which method you use. If you're getting the leaves wet when you water, then water in the morning so they can dry quickly. Wet leaves are more susceptible to diseases. If you're using soaker hoses or drip watering, then the timing isn't so critical. And somehow Mother Nature hasn't gotten the message about this yet. I just don't understand why she allows it to rain at night! LOL

Sandy

Thanks everyone. I think I'm going to go w/ some soaker hoses and I'll put down some grass clippings in a couple of weeks once it really starts to warm up around here.