Since we’ve have a week of cooler than normal late July/early August temps here in Missouri, accompanied by almost daily rain AND I just got back from picking tomatoes in the garden, I thought it might be a good time to talk about one of the most common tomato growing issues: cracking.

If your tomatoes are cracking up and you aren’t finding the humor in it, there are a couple of things you might be able to do to stop it, depending on the type of cracks you have.

Concentric cracking is when you see cracks that run around the tomato in little rings, usually at the top near the stem. This is especially common to see on the larger beefsteak variety tomatoes, although I’ve seen it on smaller ones as well. I don’t think I’ve ever see it occur on a cherry, grape or pear variety and seldom if ever on a Roma. About the only thing you can do to prevent this type of cracking is select tomato varieties that aren’t as susceptible to it. It is a genetic characteristic and is kind of like stretch marks on a pregnant woman’s belly- it leaves behind scarring and lines, but it doesn’t damage the fruit beyond usability.

Concentric cracks generally scar over, keeping bacteria, insects and rot from happening. If you can’t deal with ugly tomatoes, look for the ones that are described as smooth, perfect or have a notation about being crack-resistant. Fruits in full sun are more susceptible as are fruits growing in high temperatures; both conditions cause thickening skin in tomatoes and make the skin less elastic, so more prone to splitting. You can try picking tomatoes sooner, before they are quite ripe, but you may have to sacrifice some flavor for beauty.

UGLY maters

Longitudinal cracking is caused by water fluctuation in the soil. (tomato splits top to bottom, usually starting at the stem) Again, some varieties of tomato are more prone to it than others, but the primary reason for this issue is too much water, too fast.

Basically, the inside of the tomato expands too quickly for the skin to adapt and it splits open to relieve the internal pressure. I’ve had mine split even after I’ve picked them, caused splits by washing them when they were just on the verge of splitting on the vine. This happens more often with mature tomatoes because the skin can’t expand quickly in response to extra water.
I had a lot of splits this week because of all the heavy rain, which was on the heels of a very dry spell of several weeks. Consistent watering can help this some. If they tomatoes were already adapted to a good amount of water, they wouldn’t have been AS affected by the past week’s downpours. Same thing can happen if you let your soil dry out and then over-water it to compensate, the fruits swell up very fast in response to the sudden water available and split open.

I preach about mulch a lot on here and there’s a good reason for it- it is one of the absolute, #1 BEST things you can do for your plants. Ignore those people telling you to dump Epsom salt all over your tomatoes, plant them with buckets of crushed up eggshells, dead fish, etc. MULCH. MULCH. MULCH. Mulch and water consistently. This will help your plants more than any fad additive. Mulching can help keep the soil from drying out, which helps the tomatoes not swell up and crack as much when you do finally get around to giving them a drink.

If you’ve taken all precaution and they still crack, you’ve got a couple options. A newly cracked tomato is probably still ok to eat. Inspect the crack and be sure it doesn’t smell, doesn’t have gnats crawling on it or fungus growing in or around the crack. You can cut around the crack if it’s a large tomato and the crack doesn’t look like it’s starting to rot. When my grape or cherry tomatoes are split on the vine and the split is fresh, I just pull them off and toss them to our dog or on the ground. We get more than enough that I can afford to lose a few.

A cracked tomato won’t keep long. They’ll start drawing gnats or start to mold or grow bacteria pretty quickly, so if you don’t just toss it, you need to use it as soon as possible. Keeping them in the refrigerator can slow bacterial growth and keep gnats away. Refrigeration might give you a few hours to a couple days to use the cracked tomato.

If it smells, it’s turning black, has white fungus or bugs, throw it away.

Over fertilizing can add to the cracking problem too. Tomatoes need extra phosphorus (bone meal is a good source) and potassium when they are developing fruit. (Notice I said NOTHING about needing Epsom salt.) Well rotted compost or manure is ok, or a balanced commercial fertilizer. Green compost that hasn’t had at least a year to break down or fertilizers high in nitrogen may cause cracks, since they can result in very fast growth.

Obviously, you can’t control the weather- so week long, unexpected rain storms in the dry season mean you’re probably getting cracked tomatoes. But if the plants dry out because you went on vacation or you got distracted or just lazy, don’t soak them to the point of standing water to compensate. Instead, give them just enough water to keep the plants alive, slowly increasing the amount until they’ve recovered from drying out. Then you can get them back on a regular watering schedule.

Is it just me… or does it seem an Epsom salt rant might be in my future? 😉

-B