fertilizer.

but NRaleighLiberal will know for sure - have you read his gorgeous book?

https://www.amazon.com/Epic-Tomatoes-Select-Grow-Varieties/dp/1612122086

https://www.craiglehoullier.com/intro

They look okay. You don't have to let them spoil.

too much water from the point where the tomatoes start to ripen. cut back when they start going from green to red.

I have had that happen, too.

Oh, and you may already know this, but it is probably not a good idea to eat the split tomatoes that have burst with such great joy. They are immediately compromised with bacteria that starts growing in the flesh. It may be risky.

I've gone to picking them half ripe...they fully ripen on the kitchen counter and taste just as good but split less and attract less critters.

Don't refrigerate ..kills texture, dulls flavor.