Why Tomatoes Crack
It happens to all of us, no matter what experience level. The darn tomatoes crack.
It is frustrating that even when we know the causes, we just can’t always be as diligent as we would like taking good care of our tomatoes and monitoring soil moisture and other maintenance issues. But there are so many things that make tomatoes crack, sometimes we just have to accept that it couldn’t be helped. But the more we know, the more tomatoes we can save from cracking.
Some varieties are just plain more prone to cracking. Large Beefsteak varieties crack easily with even minor fluctuations in moisture.
Water and Temperature
When temperatures fluctuate quickly or dramatically our soil can dry out rapidly. Mulching will help the soil to maintain a constant temperature and will also help the soil to hold moisture. If our tomatoes have plenty of moisture through periods of extreme heat, that will help to prevent cracking. Keeping the soil moist consistently will also prevent cracking from a large amount of water being introduced to drying out fruit. If the tomatoes are not taking in any moisture for some period, then suddenly moisture becomes available, the tomato will take in water until it literally bursts its britches. This is why many gardeners refer to them as growth cracks.
Water consistently. Through most of the season weekly deep soaking may be plenty. As the heat of summer sets in you will gradually have to increase watering to twice per week. In periods of severe drought you may even need to water every couple of days.
If tomato plants and soil dry out, do not soak the soil. Re-introduce moisture a little at a time so the plants can very slowly recover. Do not return to your regular watering schedule for a week or two.
Make sure your plants are strong and healthy by providing adequate nutrition. A healthy plant will be able to withstand heat and drought much better than a weak one.
Select varieties that are less prone to cracking. Several types have skin that will more easily stretch such as Early Girl, Jet Star and Daybreak. Heirlooms are often quite drought resistant, one of the many reasons they became heirlooms.