By David Marks

This is one of a series of pages helping you to identify what problem, pest or disease, which is causing problems with your tomato plant. If you want to start at the beginning click here. This particular page will hep you identify and treat problems which are visible on the tomato fruits of your plant. The most common problems are listed first.


Blossom End Rot on a tomato

The likely symptoms are listed below in the order in which they normally occur:

  1. If you inspect your tomatoes regularly you will notice a small patch on the bottom of the tomato which looks translucent and a slightly different colour to the rest of the tomato. Even at this early stage there is no way to save the tomato but it will allow you to alter your watering regime sooner rather than later which will stop other tomatoes being affected.
  2. The mark will enlarge and turn brown or black ….. Click here to read our comprehensive article on Blossom End Rot.


Split skin on a tomato

Tomato skins split because the flesh inside the skin expands quicker than the skin itself. This puts pressure on the skin and can eventually lead it to tear or split.
Tomatoes normally start to split when they are nearly fully grown and the ripening process is about halfway to completion ….. Click here to read the full article.


The picture below shows clearly that the skins have brown / dark red areas of them almost as if splashed by dirty water. The marks however are in the skin rather than on it.

Dark red / brown marks on tomato skins

We have found that these marks are far more common on Gardener’s Delight tomatoes compared to any other varieties. It’s not a disease and it doesn’t affect the taste although the skins in the affected area are slightly tougher than normal. The stalk end of the tomatoes are the most affected.

None of the books or web articles we have read describe this problem although we know it affects many gardeners. It doesn’t appear to affect plants if grown in a greenhouse. From our own observations it appears to be environmental causes. Tomatoes which are not grown in full sun, or those covered with foliage are most likely to be affected.

The solution is to position the plants in full sun and ensure that does not cover the fruits.


These two conditions almost never affect tomatoes grown outdoors, they are primarily a greenhouse problem. They are caused by larger than normal fluctuations in temperature and light levels and can also be caused by irregular watering.