Blossom end rot
We kind of came late to the tomato game this year, but bought a patio type plant and two roma plants for our balcony. After initially being worried they wouldn't pollonate, I discovered there were tomatoes growing. Then a few days ago I found the largest one on the patio had what I assume is blossom end rot. And now I see the 3 smallish roma ones growing do too. They were planted in new potting soil, and are outside so have been getting regular rain and watered when we've had a dry spell. I read somewhere it can be a calcium deficiency, is that correct? Best way to correct it for future fruit or is it too late now?