Step 1 is to add dolomitic lime or gypsum to ensure ample calcium is in the growing media. If you are using a commercial, peat based mix there is a good chance it has already been limed, but it is not guaranteed and the package generally doesn't say. The package might say pH balanced or something like that in which case it's a pretty safe bet it has lime in it.

Step 2 is to do the best you can to maintain consistent water levels.

Step 3 is pray for the weather gods to not make things too hot, too cold, too humid, too dry and provide even, consistent conditions.

In my experience step 3 is the most important and the one we have the least control over. Some years will be better than others. The good news is that BER is a transient problem in most cases. No matter how high the percentage of fruits with BER is, most of the time the next set of fruit will be BER free. Why? My best guess is because the weather changed.

If i do get it, its usually on the first tomatoes only. I've had good luck putting a little Epsom Salt in with my soil. Not sure if this is proven, but i didn't have any problems this year. My container WI 55's taste awesome!

You may want to modify your soil/soiless mix for your container tomatoes for next year...like justaguy2 said "dolomitic lime or gypsum to ensure ample calcium is in the growing media" ...franktank..."epsom salts"....use a well draining mix. You should be able to see the water draining quickly down and out the bottom holes (or reasonably quickly). I had the same problem last year but made a modified "Al's mix"...not quite soiless but it drains well. I water regularly 1 litre every day...maybe a little more if the pot is 15 gals or bigger and maybe another litre if it is really hot. So this year no BER at all. Also got HEBs going with 3 diff types of tomatoes and no BER also...talk about a great way to grow tomatoes...HEB's are great. Every other day they get seaweed, or fish fertilizer at about 1/2 strength or less. Occasionally they also get a homebrew of epsom salts, manure and handfull of alfalfa pellets.

Hope this helps...

squibT

Hey, Jersey! Philly here, but originally from south Jersey! Yeah, trust me, I can empathize. Got the same problem going, and yeah, I've headed over to the tomato forum and read the FAQ sheet about BER. Read it. Living it. STILL 80% BER!

What second crop? Not many flowers anymore. Still, I remember that the squirrels ate most of our first crop last year, but we got a second crop towards then end of September, so there is hope. Also helps to know, if you pick off all those green tomatoes at the end of the season and keep them in a cool place out of the sun, they do, eventually, turn red. We had home grown tomatoes for Christmas and New Years. LOL)

Truth is, other then **possibly** water or calcium problems,(and heaven knows it's hot, humid and hazy where we live most the summer, yet Jersey still grows the best tomatoes in the country) even the scientists aren't sure exactly what causes it. Doubly annoying being from the Garden State and knowing tomatoes are so yummy, because Jersey's soil is so perfect for them. (Problem is, we can't use regular soil in containers because that soil comes complete with critters and organisms that flourish so well in containers.)

At this point, I've simply decided to divide up my tomatoes into three catagories -- healthy, some BER and BER through and through. First catagory is enjoyed the most. Second catagory can be eaten after cutting off the BER. Third catagory is trashed, even before turning red -- as in do NOT use them in composting, if you compost.

Strangely, our cherry tomatoes haven't had any at all. The one plum seems to be nothing but BER, and the other three (Big Mamas from Burpee) are hit or miss, usually hit. Still, thanks to the cherry tomatoes, we (just two adults) have enough tomatoes for our salads, and the rest have been giving us enough usable tomatos to have tomatos every night for dinner.

Ya know that old saying, "If life gives you lemons...?" In our case, best we can do is go with if life gives us tomatos with little or no BER, rejoice and eat heartily! ;)

If you have good soil, then a regular stable watering schedule should fix the problem. I learned that the hard way. Plus I switched my soil mix to compost/manure with a healthy dose of perlite and grow my tomatoes in 20-inch diameter containers. It's working now for 15+ years. Good luck.

"Step 1 is to add dolomitic lime or gypsum to ensure ample calcium is in the growing media"

Keep in mind. dolomitic lime will alter/sweeten/raise your potting soil pH (making other nutrients unavailable) and provide calcium + magnesium.
Gypsum provides calcium + sulfur, but does not change your pH or sweeten your potting soil.
I have always heard/read blossum end rot is a lack of enough calcium, but it is much easier to put too much dolomitic lime than gypsum...add gypsum to be on the safe side.