Cracks in Tomatoes

Q. What causes cracks in the tomatoes near the top where the stem is? I have also seen some of my tomatoes with very deep cracks. Let me know what you can tell me about this.

The types of cracks speaks volumes. Longitudinal cracks, like this one running the length of the fruit, is caused by expansion of the fruit when it is ripening. Cracking that are radial, or run around the fruit is mostly genetic.

A. There are two types of cracking, longitudinal cracks (which you have) and radial cracking (which you don’t have). Yours are longitudinal cracks. Radial cracking is mostly a varietal issue. Some varieties of tomatoes show these radial cracks more than others. If you have radial cracks, grow a different variety next season. That will lessen, but not eliminate, radial cracking.

This is a so-called "Heirloom" variety called 'Caspian Pink'. It demonstrates radial cracks typical of the variety 'Caspian Pink'. Not much you can do about it except lessen it under better conditions but the radial cracks will still be there. All type of cracks do not harm the fresh eating of these fruits unless it spoils.

            Another possibility is uneven amounts of water to the fruit. These types of skin cracking causes mostly longitudinal cracks. The swelling of the fruit and then shrinking back to its original size can cause cracking because of the expanding fruit. This type of cracking (longitudinal cracks again mostly) is lessened by using a surface mulch on top of the soil. Sometimes watering differently will help. 

Longitudinal cracking of the fruit by irregular watering even with a surface mulch of straw applied.

If you are using surface mulch, I would recommend wood or pine shavings (like rabbit, horse, or hamster bedding). It “melts” (decomposes) into the soil easier than straw which has fibers that are tough to decompose. Straw works but is more difficult to get it to break down quickly.

            You don’t need a thick layer of surface mulch but just enough to shade the ground and lessen water lost by soil surface evaporation.