It doesn't matter what I do, my Cherry tomatoes always seem to have many of them crack when/as they ripen. I have tried everything - more sun, less sun, more water, less water, different varieties etc. It only seems to happen badly with Cherry tomatoes. I am not talking about the occasional crack that sometimes happens early on the fruit is green and then heals to forms a dry scar over time. This is the kind of splitting that happens suddenly, just when the fruits become ready to pick. Is this a common problem? Does anyone have a solution? What might I be doing wrong?
Small fruiting tomatoes tend to be a lot juicier (that is ratio of meaty pulp to juice) than medium or large fruiting. Tomato produces a skin of a certain size for the number of fruits it has, then as b.nota points out extra water arrives. The fruit is already turgid, the extra water has nowhere to go but to burst the balloon. It is particularly a problem with tomatoes grown outside, subject to the varying weather: overnight dew, shower after dry, downpours. A few drops more in a large meaty tomato is easily absorbed, but the already watery small fruit cannot handle it.
Think of the advantage that a greenhouse grower has. Full control over when and how much irrigation to apply. Tomato fruits come out perfect every time and he can sell every one.
There is also physical pressure to take into account, that is being bumped or leaned on. Commercial growers pack in small containers so that being leaned on by neighbours or crushed by a heavy overburden of other fruits does not happen.
Frequent and early picking (just showing some red blush) can help.
There are two main causes of fruit split - the first is irregular watering. Once tomatoes have fruitlets, and especially as they start to get bigger and ripen, its critical to water sufficiently every day, without missing a day or two, or giving a bit less some days than others. If you don't, then the tomato, receiving a sudden influx of water, swells rapidly, and the skin can't keep up and splits. So, if you usually water twice a day, then always water twice a day, with the same amount, every day. Or once a day, whatever your regime is...In a hanging basket, its much more difficult to keep the watering ritual accurate because they dry out quicker - they should certainly be watered at least twice a day, and watered well each time - even if it's raining.
The second cause is, unfortunately, fluctuation in temperatures, which is much more difficult to avoid when growing tomatoes outdoors https://www.rhs.org.uk/advice/profile?PID=393