Cracking the Code: Exploring the Factors Behind Splitting Tomatoes
In the area of Kansas where I live, the USDA hardiness map considers it to be zone 6a, which means the average minimum winter temperature every year is between -9 °F and -4 °F. This map allows us to understand what plants are hardy and will grow well in our area, but because of climate change, the zones slowly shift on the map year by year, reclassifying areas into slightly different zones.
This year's summer has been quite strange; we will have some hot days followed by bouts of on-and-off rain, and this pattern will cycle. Not only does this cause rapid changes for the plants, but it also creates a lot of humidity. Due to this weather cycle, my garden has encountered some interesting issues.
What I have been Experiencing
Now that the growing season is in full swing, there are lots of things happening around the garden. Flowers are blooming, Pollinators are doing their job, and Fruit is ripening. The fruit I was especially excited to see grow this year was my assorted variety of tomato plants. Specifically, I was eager to try the Honey Comb Hybrid variety, as it reminded me of popping cherry tomatoes like candy in my grandma's garden. So as one does, I watch them grow, and one day the fruits appear and begin to ripen. I waited and waited, and when they finally turned a beautiful, shining orange color and I went to take a look, to my surprise, they were starting to split. I was very upset that all my hard work had gone down the drain while simultaneously being confused as to why this was happening. So, as any horticulturist would, I did some research and found out why. What It Means When Your Tomatoes Crack
Types of Cracks
One of the first things I found out was that there were two different types of cracking on tomatoes. The kind of crack that I had on my tomatoes, as pictured above, is called radial cracking and results in a vertical split down the tomato. This type of crack is detrimental because it goes down to the flesh of the fruit, which can leave it open to infection.
The other is called concentric cracking, which is displayed as multiple cracks occurring in a circular pattern around the stem of the fruit. This type of cracking is not as bad because it doesn’t penetrate down to the flesh; it stays at the surface, which reduces the chance for disease. Radial splitting is the worst of the two because it can affect a larger area of the tomato, but both types can result in the fruit rotting on the vine if left to do so.
Why Do These Cracks Occur?
Cracking and splitting often occur in late summer when there are rapid changes in water availability, which can cause the fruit to expand faster than the skin can grow. The most common way this change in the soil occurs is when there is heavy rainfall followed by periods of hot, dry weather. This mostly affects fruit that is in the process of ripening but can also impact green or unripe tomatoes. Cracking and splitting can also be the result of other tomato diseases, like blossom end rot.What should I do?
How to prevent splitting and cracking and how to remedy it once it happens
Although there are many factors that contribute to splitting and cracking, the main culprit is the large fluctuations in soil moisture content and water availability. Tomatoes require about 1 to 2 inches of water per week in order to ripen. Not only is the amount of water the plant receives important, but the rate at which it is received also impacts whether or not the fruit will split. That’s why consistent and even water content in the soil is key to preventing splitting and cracking. To ensure you are keeping the plant evenly moist, you can use an irrigation system, or if you’re hand watering, try to water very deeply a couple of times a week instead of a little bit every day, as well as keeping the water consistent during droughts. If you are hand watering, you may also want to take a look at the way you water. Instead of overhead watering the foliage, try to water at the base of the plant. When you water overhead and on the foliage, it can not only cause leaf diseases but also reduce the amount of water that actually gets to the roots because of evaporation.Other things you can do to stop your fruits from splitting are to mulch your garden, which minimizes the amount of evaporation and keeps the soil moisture consistent. Picking the fruits before a storm or large fluctuations in weather can also help prevent splitting, but you will have to ripen them on the counter, which can cause them not to be as flavorful. Sometimes even fertilization can be a factor in splitting, so personally, I put compost down, then cardboard on top to suppress weeds, and finally some mulch to keep all the moisture in and minimize evaporation.Splitting and cracking are not the only issues that affect tomatoes when there are large fluctuations in temperature and soil moisture. Other issues include blossom end rot, leaf curling, wilt diseases, and even early blight. This is why watering overhead is not recommended because it can cause leaf diseases like these, which can slow the plant's fruit production or just flat-out kill your plant or rot your fruits. If you think your crop of tomatoes has a disease and want to get it diagnosed, you can reach out to your local extension agent or have it sent in to be tested by a lab.Sources
Concentric Cracking. (21 C.E., June 3). Gardening Know How. https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-cracking.htmGlen, C., & Boone, T. (2020, March 27). What Causes Tomatoes to Crack? What Causes Tomatoes to Crack? | Extension Marketing and Communications. https://pender.ces.ncsu.edu/2020/03/what-causes-tomatoes-to-crack/Tomatoes: fruit splitting and cracking / RHS Gardening. (n.d.). Tomatoes: Fruit Splitting and Cracking / RHS Gardening. https:///problems/tomatoes-fruit-splitting-and-crackingToscano, K. (2022, July 18). Why tomatoes split and how to prevent it. Southern Living. https://www.southernliving.com/garden/edible/why-do-tomatoes-split 