Fruit cracking is a common problem in tomatoes when there is a wide fluctuation in soil moisture levels, which leads to inconsistent water content within the plant. This is usually caused by huge temperature variations and/or inconsistent irrigation.
The cracking or splitting of tomato fruit can take two forms:
- Radial cracking, where the cracks radiate out from the stem end, and can form a star shape around the top of the fruit.
- Concentric cracking, where the cracks form rings that circles around the stem end.
Both types of tomato cracking can be caused by various environmental and growing conditions, such as:
- Uneven watering
- Very fast growth
- Excessive moisture (rain or heavy watering) after a dry period
- High temperature
- A large difference between day and night temperatures
- Inadequate nutrition
What Makes Tomatoes Crack?
After a long, dry period, if heavy rain falls or a deep watering is carried out, plants takes up available water very quickly, causing the ripening fruit to crack.
The cracks are caused when the inside of the fruit grows faster than the outside, the fast internal growth spurt causes the skin to split open.
Generally, fruit cracking occurs more commonly with the larger, beefsteak-type tomatoes.
Can You Eat Tomatoes That Are Showing Signs of Cracking?
If tomatoes split, they’re still safe to eat, and shouldn’t be thrown away. If the split portion looks less appetising for some reason, cut that part away, the rest should be fine if it looks normal and the cracked portions aren’t mouldy.
How to Prevent Tomatoes from Cracking
It’s not possible to avoid all cracking, but the severity of the problem can be reduced by mulching the soil, providing tomato plants with a consistent supply of moisture during the summer months, and ensuring that adequate fertiliser is used during the growing season.
Water – During dry summer periods, water regularly and consistently, using a slow, deep watering to thorough soak the soil. How often depend on the temperature, wind and soil type, but at least once a week would be the minimum for most tomato plants. Typically, watering may be required three times a week.
Mulch – To prevent evaporative loss of water from the soil surface, conserve soil moisture by mulching the soil around tomato plants using straw, pea straw, lucerne, sugar cane mulch, dried grass clippings, shredded leaves, or other mulch material.
Fertiliser – Apply a slow-release fertiliser such as manure to the soil before planting, in early spring, then if desired, apply additional fertilise (beneath the mulch) every 8 weeks during the growing season.
There isn’t much that can be done about large day-night temperature variations that can occur when the fruit is maturing, but it helps to plant tomato varieties that are known to possess good crack resistance.
- Iowa State University Extension and Outreach, Horticulture and Home Pest News, Why are my tomatoes cracking? https://hortnews.extension.iastate.edu/faq/why-are-my-tomatoes-cracking
- Mississippi State University Extension Service, Tomato Troubles: Common Problems with Tomatoes, Publication Number: P2975, https://extension.msstate.edu/publications/tomato-troubles-common-problems-tomatoes
- University of Florida IFAS, Extension Nassau County, Q: My Tomatoes Are Cracking In Circles Around The Top. What Causes This To Happen? Posted: July 15, 2017, https://blogs.ifas.ufl.edu/nassauco/2017/07/15/q-tomatoes-cracking-circles-around-top-causes-happen/