tomatoes that rot at the blossom end...

[grasswire]

...what's going on there?! They hang on the plant looking all gorgeous but the bottom end is bad.

Is it safe to cut off the bad part and eat the good?

[Zoigal]

1. Probably a watering problem

I normally cut off all the bottom part that is affected and eat the rest. Try and be consistent with the watering
schedule. Good luck.....z

[dgibby]

2. It's called blossom end rot.

http://vegetablemdonline.ppath.cornell.edu/factsheets/Tomato_BlossRt.htm

It's not a watering problem. It's a disease.

[grasswire]

3. a long hot spell probably is the culprit

thanks for that article.

[formercia]

4. It's not caused by a pathogen

"The occurrence of the disease is dependent upon a number of environmental conditions, especially those that affect the supply of water and calcium in the developing fruits. Factors that influence the uptake of water and calcium by the plant have an effect on the incidence and severity of blossom end rot. The disease is especially prevalent when rapidly growing, succulent plants are exposed suddenly to a period of drought. When the roots fail to obtain sufficient water and calcium to be transported up to the rapidly developing fruits, the latter become rotted on their basal ends."

I always sprinkle some Dolomitic Limestone around the base of my tomato plants and make sure they get sufficient Water.