Why Tomatoes Crack When Growing

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If you have grown tomatoes for any period of time, you’ve experienced “tomato cracks.”

Most tomato cracking is due to sudden growth in the tomato fruit from excess water. The inside of the tomato expands faster than the outside skin can grow to enclose it. The skin can eventually stretch no farther, so it cracks.

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Cracking results as a way to relieve the pressure caused by excessive soil moisture levels and other reasons.

There are several other causes of splitting in ripe tomatoes, and careful inspection of your plants in your vegetable garden may lead you to discover the exact cause of the concentric cracks.

What Causes Tomatoes to Split or Crack?

1. Over-watering

Your tomato plants need a lot of water most of the time. The temptation, as tomato flowers turn into green tomato fruits and then ripen, is to add even more water. 

However, excessive watering and heavy rainfall can lead to concentric cracking in the tomato skin. So you should continue to supply the plant with the same amount of water as before on a regular basis. 

But be careful not to overwater your tomato crop. Giving excess water will cause root rot and kill the plant. It’s also best to maintain well-draining soil to prevent this. 

Ripening tomatoes on vine.Pin
Photo Credit: Instagram @anne_schmitt

Also, remember that any heavy rain counts toward the total, and you should reduce the supply of water accordingly. Your goal is to keep the level of soil moisture about the same. 

Soaker hoses and drip irrigation are excellent for watering without getting the tomato leaves wet and reducing fluctuations in soil moisture.

2. Excessive Sun And Dry Weather

Too much sun can burn the skin of the tomato, which undergoes stress and cracks on its outer skin. 

Tomato plants like a variable temperature range between 70° and 85° degrees Fahrenheit. 

Hot weather also provides both excessive heat and light, so a good first step to eliminate the sun as a source of tomato splitting is to find an area that has a little shade from the most intense heat and light of the day in a dry period. 

Split orange tomato on vine in hand.Pin
Photo Credit: Instagram @thetomatogeek

A tree with an east-facing exposure, or an east-facing wall, to let the plants have the morning sun without having the intense glare of the noontime and afternoon is ideal.

If a shady spot is not an option for your tomato plants, an alternative is to place a shade cloth over the plants.

3. Rapid Temperature Changes

A drastic difference between night-time, morning, and afternoon temperatures can cause tomato splitting. Little can be done about the daytime temperature, but a sheltered spot can provide a more even temperature.

In each case, the amount of water inside the tomato is probably the ultimate cause of the tomato cracks, either directly, from too much water, or indirectly, from the light and heat, or lack of it, dry spells, expanding and contracting the fluid inside the fruit.

4. Mineral Deficiencies In The Tomato Plant

Tomato plants need nitrogen, phosphorous, and potassium, just like other plants, to promote healthy growth. 

Too little will leave the plant unable to develop fruit quickly enough and may be prone to tomatoes splitting. 

Paradoxically, too much nitrogen will encourage very rapid growth, which may leave the inside of the fruit growing faster than the skin. 

Moreover, calcium deficiency can also cause radial cracks in tomatoes because it is linked to water uptake and ripening. 

Applying a balanced fertilizer just as the tomatoes are setting blooms should provide enough nutrients for the plant while not providing too much.

Hand holding a cracked red object.Pin
Photo Credit: Instagram @rebeccakolls

5. Some Varieties Of The Tomato Plant Are Prone To Cracking.

Some varieties of tomatoes are bred to have extremely high sugar content. The excess sugar in the tomato can sometimes contribute to concentric cracking. 

Also, some varieties of tomato, like the beefsteak varieties, are designed to grow to very large sizes very quickly. While you may get an enormous tomato using these varieties, you may also get a cracked tomato.

Types Of Cracking Splitting Tomatoes

Tomatoes are usually split in one of two different ways. Radial cracking or vertical splits develop along the side of the tomato fruit. Concentric splitting develops in circles around the top of the tomato fruit, making a ring around the stem.

In either case, the best option is to harvest the split tomato as soon as you spot it. Inspect it carefully. If it has any signs of rot or oozing or has common tomato pests, you should not eat the tomato but instead discard it. Otherwise, you can remove any damaged portion of the fruit and use the rest.

Close-up of a ripening tomato with a split skin.Pin
Photo Credit: Instagram @woow36

If the fruit is not fully ripened, you can still harvest the tomato. Simply put it in a paper bag for a time, and check it over the next several days. The paper bag will help the natural ethylene in the fruit finish the ripening process.

One useful way to reduce the amount of splitting in your tomatoes is to harvest them before they have fully ripened. They can ripen for a day or two on their own or in a bag.

If the split has affected a green tomato, then using a paper bag may not speed up the ripening process quickly enough. You can still use a green tomato in a variety of tasty recipes, so it need not go to waste.

Other Tips To Prevent Tomato Cracking

  • Choose your variety carefully. Some tomato varieties are specifically intended to reduce splitting. Your seed catalog should contain varieties of crack-resistant tomatoes for your zone.
  • Use organic mulch on your tomato plants. Carefully mulching your tomato plants can help retain even levels of soil moisture and prevent overwatering.
  • “Red Tomato Mulch” can also assist your tomato plants’ development. Red tomato mulch refers to a red plastic ground cover that can be purchased in garden centers. It does nothing to fertilize the soil or aid water retention. Rather, it reflects certain wavelengths of light back upward to the plant. These wavelengths encourage faster growth in the fruit. If the tomato can expand faster, the theory goes, it will be less likely to split.

How Is Blossom End Rot Related To Tomato Splitting?

Sometimes, tomatoes don’t split in a radial or concentric pattern but instead begin to turn brown or black and split at the bottom. This is called blossom end rot. It is often due to a lack of calcium in the soil. 

"Tomatoes with quirky peel patterns on wood"Pin
Photo Credit: Instagram @the.mega.tomato

Blossom end rot can also be caused by low soil pH or extremes of temperature. These tomatoes will not ripen in the normal way, and they should be discarded.

Is A Cracked Tomato Fit For Consumption?

Depending on the severity of the fruit cracking, the tomato can still be consumed. A tomato with a wide crack can act as a reservoir of fungus, bacteria, and mold, as it can attract fruit flies.

Avoid any split or cracked tomato when doing tomato canning.

However, you can cut around the cracks and use the good parts in sandwiches, salads, sauces, and salsas. The taste of the tomato is not affected by the parts not cracked.

If you spot a tomato close to ripening and beginning to crack, remove it from the plant and let it ripen on the kitchen counter or windowsill.

Leaving it on the plant will worsen the situation as it will continue to absorb water, and the crack will continue to widen.

Quick Tips To Prevent Cracking or Tomatoes From Splitting

Keep Water Supply Regular -The best way to prevent the cracking or splitting of tomatoes is by keeping your watering frequency consistent and regular.

Close-up of green and red tomatoes.Pin
Photo Credit: Instagram @bennettcreeklife

It’s better to water your tomatoes deeply regularly than to water them sporadically and shallowly. Make sure you have a regular plan for watering, which adjusts to the amount of rain received.

Plant Crack-Resistant Varieties – these types of tomatoes have elastic skin. New varieties are introduced every year. Some include Daybreak, Earl of Edgecombe, Early Girl, Heinz 1350, Juliet, Valley Girl, Mountain Delight, and Mountain Pride.

Apply Balanced Fertilizer – when blossoming and fruiting, tomatoes require more potassium and phosphorus. Excessive nitrogen will cause excessive growth, leading to cracking. Conduct a soil test first to determine the nutrients present in the soil before adding more.

Avoid Over-Fertilizing – Over fertilizing your tomatoes with excess nutrients can lead to a growth spurt. We always use Epsom salt on tomato plants when planting seedlings to give them a boost and reduce transplant shock.

Additional Tip

If the tomato plant dries up, don’t water them too much, as that can set up the condition for splitting.

Once it has recovered from the dry spell, systematically re-establish the regular watering schedule.

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