Hi! I'm a very very new gardener and I've been taking care of this cherries since they were seeds from their original tomatoes. I know the topic of yellow leaves has been answered several times, but there are so many answers I just don't know what might be affecting mine! So there's a picture of the yellowest leaves on my plants. This started happening about a week ago, several leaves have turned brown or yellow, specially the old ones. I'm worried that this might be some disease that's going to kill them all! or maybe it's just normal behaviour? I'm worried because several of the large ones turned yellow brown all in the same week or two.

Anyway, they're planted in containers in a half and half mix of miracle gro potting soil and prepared sterile soil (half black dirt and half leaf compost) . I've fed them soluble all-around fertilizer (17-17-17 I believe?) twice, the first time I transplanted them to their current containers from their smaller ones and about a month after that. They've actually been doing wonderful, growing a lot and producing a lot of flowers, right now all the tomatoes are green and they've been that way for about a month, but I've read that it can take a while for them to turn red, so I'm not that concerned about that.

Does anyone know what I'm doing wrong?? I would really appreciate any help, I don't want to kill them!