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Mike McGrath

Why Your Tomatoes Are Splitting & How to Prevent It


Table of Contents

When you're dreaming of harvesting the perfect, sun-ripened tomato, it's so frustrating to find a bunch with splits or cracks on their sides. The good news is that with a few changes in your gardening practices, you can prevent this common tomato problem and enjoy beautiful tomatoes.

What Causes Tomatoes to Split?

The two types of splitting or cracking in tomatoes are the circular cracking near the top of the fruit and the vertical splits. The circular cracking happens most often in old-fashioned beefsteak tomatoes. When this happens, just pick the fruits and cut off the cracks. Often the top part of the fruit with the cracking is not ripe anyways.

The vertical splits are often the result of water inconsistencies. These most often happen when the plants have experienced a dry spell. Then, right before the fruits ripen, they receive excessive rain. The fruits take in the water, expand and crack. When the tomatoes crack, other problems can follow. The cracks expose the fruits to insect pests and diseases.

How to Prevent Tomatoes From Splitting

Gardeners can take several steps to prevent tomatoes from cracking. The key is to start your prevention program when transplanting your tomato plants into the garden.

  1. While you can't control the rain, mulching around the tomato plants helps the soil maintain its moisture and reduces the likelihood of the soil becoming too dry. It also suppresses weeds and helps prevent the spread of disease. A red plastic mulch also boosts yields.
  2. Water tomato plants every 3-5 days if they do not receive adequate rainfall. This helps prevent the shock of excessive rain.
  3. Give the tomato plants the nutrients they need. Having adequate nutrients, especially calcium, can help the plants regulate their water intake. Slow-release, all-natural fertilizers, such as Tomatoes Alive!® Tomato Fertilizer, promote steady, strong growth.
  4. Select tomato varieties that resist cracking.
  5. Pick fruits before predicted rainfall. Partially ripe tomatoes will ripen off the vine. By learning how tomatoes ripen and when to pick them, you can prevent them taking in too much water and cracking.

What to Do if Your Tomatoes Are Split

If your tomatoes split, harvest them immediately. Leaving them on the vine makes the plants susceptible to tomato pests and tomato diseases. Whether the fruits are salvageable or not, you should remove them from the vines.

Can You Eat Cracked Tomatoes?

Before eating cracked tomatoes, inspect them and smell them. If they smell sour or have signs of insect damage or rot, don't eat them.

If harvested immediately, the cracked tomatoes can still be eaten and enjoyed. For fresh eating, just cut off the cracked areas and use the tomatoes on sandwiches, in a fresh caprese salad or salsas.

Often the best use for cracked tomatoes, especially if you have lots of them, is to make a homemade tomato sauce. You can also cook them into other tomato garden recipes.

Because split tomatoes don't store well, plan to use them right away.

Mike McGrath

Expert Advice

Q: I have a problem with my heirloom tomatoes cracking after heavy rain (a rarity here in central Texas, but it does occur).

---Brooks in Austin

Although, I don't have any big problems growing tomatoes, they do tend to split. What am I doing wrong and how do I fix it?

--- Kim in Norwich, CT

After reading your tomato growing book last year I am happily harvesting organic Brandywines and Romas. However, most of the Brandywines developed deep crevices up near the stem. Other than that, they are beautiful. I looked in your 'A to Z archives' but didn't find any answers. Do you know why tomatoes would crack?

--- Ed in Milmont Park, PA

A. 'Cracking' and 'splitting' are such common problems that I was kind of shocked we hadn't addressed them yet—especially since the answers are all relatively good news: Cracking and splitting aren't caused by some dread disease or awful insect; they're more of a cultural problem—like opera and my radio show.

Anyway, tomatoes split open when the skins of the ripe fruit can't keep pace with the growth of the insides—especially when that growth is sudden and rapid, like right after a rain that falls heavily in a short period of time; and especially if the rain was preceded by a long dry stretch. Once a tomato is ripe, the outside is pretty much done growing, but the inside is still going to take in some of that water—and sometimes the skin gives way.

This isn't typically a problem with green tomatoes; their parts are still growing at a relatively equal rate. And the fact that only ripe tomatoes are affected means you shouldn't lose any fruits. If a heavy rain is predicted—especially after a dry spell—go out and pick all your ripe-to-mostly-ripe tomatoes (they're only going to lose flavor from all that excess water if you don't). Otherwise, pick fruits that start to split promptly and use them to make sauce or salsa. Heck, if the splits are small and you act fast, they'll still make good slicing tomatoes. Don't leave split tomatoes on the vine—the openings will attract opportunistic insects like ants.

Although, it may seem similar, 'cracking' around the tops of heirloom tomatoes is a different issue—more of a 'price you pay for a great tasting big old-fashioned tomato' kind of thing. Almost, all of the old original big 'beefsteak' sized tomatoes are prone to at least a little bit of cracking around the tops, and most of the time it isn't a problem. Just pick them, slice off that top 5% and enjoy the rest. And besides—some of the really huge heirlooms never seem to want to ripen all the way to the top, so it makes sense to pick them when they're still a little green-shouldered anyway; otherwise you risk them getting overripe on the vine and losing flavor.

But again, this is at least partially a 'cultural' problem, and so there are some things you can do up front to lessen the possibility of splitting and cracking. Growing in raised beds, for instance. Tomatoes grown in raised beds are always going to have the problem less, because heavy rains will drain away faster in the light, loose, un-stepped-on soil of a properly raised bed. Flat-earth gardeners with compacted soil will always have more cracking and splitting.

A one to two inch mulch of compost, shredded fall leaves or straw will also help by keeping the soil moisture more constant. Again, you get the worst splitting when a lot of rain follows a very dry spell, and mulch can help keep the moisture levels higher during dry times, which helps the skins stay more flexible.

And then there's the importance of calcium. Having access to adequate soil calcium allows tomatoes to better regulate their water uptake, which is why we always advocate adding calcium at planting time to prevent the heartache of blossom end rot—when ripe tomatoes turn black and rot out on the bottom ("the blossom end").

A dozen finely crushed eggshells in the planting hole pretty much totally prevents blossom end rot, and should help prevent splitting. In fact, blossom end rot is a kind of 'worst case splitting', as both are caused by too much moisture building up inside ripening fruits. And this is a great time to start saving dried eggshells for next season.

Don't eat eggs? Natural plant foods labeled for use on tomatoes will contain a lot of added calcium, specifically to prevent these kinds of problems. If it's a granulated fertilizer, add some directly to the hole at planting time, and then add the recommended amount to the surface of your soil (or mulch of compost), then cover the fertilizer with a little more soil or compost. (Granulated plant foods always work best when they're incorporated into your soil as opposed to just sitting on top of it.)

And finally, you can plant varieties that are known to resist the problem. Look for tomatoes whose catalog descriptions say things like 'crack-free'; these varieties are bred to have skins that continue to expand when the fruits are ripe.

While cracked tomatoes are common, you can take steps to reduce their likelihood. Provide your tomato plants with the right nutrients and a steady supply of water, and you'll be on your way to gorgeous, sun-ripened tomatoes.

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