Maintain a constantly moist soil. Blossom End Rot is generally a watering issue out here in Arizona.

A thick layer of mulch and a drip irrigation system to keep the soil moisture level constant usually works.

We have plenty of calcium, but erratic moisture levels will also produce that damage.

Are you sure they were getting pollinated? My zucch's that don't get pollinated look to rot/turn yellow from the blossom end until they fall off.
Hardly any bees around at my house, I have to manually pollinate them.

Just a guess...

Kevin

Thanks guys. Kevin I see to it that my Blossoms are well pollinated I go out there every day with a paint brush And spread the joy:)
Lazygardener I have raised beds full of Compost and tons of egg shells , and its on a soaker hose, I will mulch more next year.
I thought there was a fungus that caused it.

For mulch I have been happy with wood chips from a local arborist. He's at 23rd Ave and Northern and usually has a pile of wood chips in his yard that can be had for the elbow grease of bringing your own pitchfork.

I'm not sure I can post contact info publicly in this forum. Anyone interested you can email me from my User Name link.

It's best to use it as a thick mulch now, turn it in when you want to rest the soil for a few weeks between growing seasons. Some say that the process of composting wood chips in your soil causes an issue with nitrogen and micro-nutrient uptake. Others say this is just urban legend/old wive's tales. Take your pick.