Tomato problem...help

[mom2chrisnluke]

My yellow pear tomato have a large brown spot on the bottom of many of my new tomatoes. I think it is blossom bottom rot? What do I do about this? What am I doing wrong? It is not all the tomatoes just some, any tips?

[LadybugSam]

that can be a sign of them needing more calcium

[Macky]

You're correct... sounds like blossom end rot. :(

A few points from this page (http://gardenline.usask.ca/veg/blossom.html) from my local university extension:

- Blossom-end rot is worse when excess moisture is followed by dry conditions.
If I recall, you realized a while ago that you may have been over-watering. If you suddenly went to the opposite extreme, this could have been a contributing factor.

- High levels of certain nutrients, mainly nitrogen and potassium can also stimulate blossom-end rot. Nitrogen is often in excess in home gardens, thus encouraging rapid growth, and an enhanced chance of the disorder.
Many gardeners over-fertilize with nitrogen because nitrogen makes for lush plants. It's an easy thing to do with synthetic, water-soluble fertilizers.

- Organisms that convert the calcium from the unavailable to available form are not active in the cold soils. As the soil warms, the organisms become more active, and thus more calcium is available.
I don't think cold soil was an issue in your case, however, by not planting in the ground, the organisms they're talking about here were likely not present in your growing medium at all in the first place. Bagged commercial potting soils are practically, if not entirely sterile.

Your potting soil likely has all the calcium your tomatoes need already in it, however, that does no good if it's not accessible to the plant. You can side dress with a calcium source if it makes you feel better, but I doubt it's necessary. Take off the damaged fruit so the plant isn't putting any more effort into them. Pay attention to keeping water and fertilizer applications only as much as necessary, no more. You can still get undamaged fruit from these plants if conditions are remedied. :)