Tomato Zippering – Why It Happens? 2 Ways to Prevent It!

Tomatoes are a delicious and nutritious fruit that can be enjoyed in many different ways. However, sometimes when you grow your tomatoes, you may bump into tomato zippering. This can be quite frustrating and sort of ugly looking. It also can make the tomato difficult to eat.

But why does this happen? And is there a way that you can prevent it? Let’s go with the short answer for those of you that are in a hurry and then expand more for those who’d like to learn in more detail.


  • Tomato zippering is a harmless cosmetic disorder on the outer skin of the fruit
  • There is an indication that it’s caused by cold weather and high humidity
  • You can prevent it by choosing cold resisting tomato variety and controlling the humidity (between 65-85%)

What is Tomato Zippering?

This is a common issue that doesn’t usually get a lot of attention because it’s not harmful to the plant or us when we eat it.

A narrow, brownish longitudinal tissue resembling a zipper that runs from the stem end to the flower end is commonly known as a zipper on tomatoes. The so-called “zipper” doesn’t penetrate the fruit itself, it’s only on the outside part of the skin.

In some cases, nearly the whole tomato can be covered in zippers which is frustrating.

Some gardeners confuse the zippers in tomatoes with another disorder problem called “catface“, but they have distinct symptoms and are not the same disorder.

tomato catfacing

What Causes Zippering on Tomatoes?

It is the result of a congenital defect during fruit development that alters the establishment and growth of various fruits, typically when anthers remain attached to the newly forming and growing fruit. In some cases, it could be also connected with incomplete shedding of flower pedals during fruit formation. 

There is a possibility to avoid it but that involves selecting an appropriate tomato variety. In terms of attempting to control this abnormality after it’s formed on a tomato, you’d be wasting your time as it’s impossible. Once it’s formed, there’s no removing it.

tomato zipper

When it comes to external causes, some suggestions are showing that the zippers on tomatoes occur more frequently in cool weather. There are certainly some varieties that are known to be more prone to this disorder – for example, the Wapsipinicon peach, and Black Zebra.

Another suggestion is very high humidity. The explanation here is simply – the humidity makes the developing fruit more sticky, hence, the chances for the alters to adhere to the fruit in development are much higher.

How to Prevent Zippering in Tomatoes?

The only way that you can prevent this is by choosing to grow tomato varieties that are known to be more resistant to cold. Here are 7 tomato varieties that would less likely to develop this disorder:

  1. Oregon Spring.
  2. Celebrity.
  3. Siletz.
  4. Orange Pixie.
  5. Golden Nugget.
  6. Husky Gold.
  7. Red Deuce

If you can’t get your hands on some of the cold-resistant tomato types and go for another one, try to control the temperature if possible. The ideal temperature should be between 65-85˚F or 18-30˚C.

In addition to that, if you grow your tomatoes in containers, indoors, or in a greenhouse, make sure you control the humidity level of the environment. The optimal level for tomatoes is between 65% and 85%.

Is It Safe to Eat Tomatoes That Have Zippers?

Zippering in tomatoes is not harmful to the tomato itself, but it can make the fruit less attractive. The brown scar that goes down on the skin is a purely cosmetic issue.

You can simply peel off the skin or cut out the parts with the zipper and use the tomato the way you’d normally use it. 

Bottom Line

Even though this fruit disorder is not uncommon, there’s not so much information about it. Since it’s not a harmful problem like some other tomato diseases, you can mostly ignore it and enjoy the tomatoes as you would normally.