Cracked tomatoes. Credit: Sam Schipani | BDN

This story was originally published in September 2020.

It’s that time of year: tomatoes are ripening and ready for harvest. But some growers might be noticing something unexpected: cracked tomato skin exposing the juicy, seedy flesh on the inside. Maybe that crack has developed a crisp white tissue, or perhaps filled with black gunk that fruit flies can’t seem to get enough of. What’s causing it?

Splitting in tomato skin is a common garden problem, and one that can be prevented in years to come with a few simple steps.

“Tomato cracking [or] splitting is caused by inconsistent moisture,” said Caleb Goossen, organic crop and conservation specialist at the Maine Organic Farmers and Gardeners Association. “Essentially a wet period of rapid fruit expansion right after a dry period can cause the fruit to grow faster than its own skin does.”

Goossen explained that earlier on in a ripening period, such cracks are less damaging to the overall health of the fruit. Then, there is a greater chance for the tomato to grow a sort of “scar tissue” over the split. However, ripe fruit with splits are especially susceptible to fruit flies and decay, like mold or soft rot.

“There’s nothing wrong with eating tomatoes that have split open, particularly if the split has healed over,” Goossen said. “However, you do want to look out for fruit flies and decay that may have found their way inside the open tomato. It’s usually very evident that decay is happening, and you wouldn’t want to eat tomatoes that look and smell like that anyway.”

Cracked tomatoes. Credit: Sam Schipani | BDN

Unfortunately, there isn’t much that can be done about tomatoes once they have cracked. However, you can take preventative measures to prevent cracking and splitting in future seasons by being more consistent when watering your tomato crops. Goossen said to even water lightly the day before a rain storm is predicted to make sure your plants are getting enough (but not too much) water.

Goossen said that you can also opt to pick tomatoes before they are fully ripe, as they will continue to ripen off the vine and are less susceptible to decay and insects if they finish ripening indoors.

Some varieties of tomatoes are also more resistant to cracking than others. Consider opting for those types of tomatoes instead in the future.

“Varieties with thin skins meant for optimal fresh eating tend to be more susceptible to cracking, while varieties that are less susceptible to cracking are usually thicker skinned and meant for shipping [and] processing,” Goossen said. “Heirloom tomatoes usually haven’t been selected to have tough skins, and can be susceptible to cracking.”