I bought yellow cherry tomato plants from a nursery that already had tomatoes on them. I transplanted them and although the plants have gotten bigger, they are still very short compared to the red cherry tomatoes I also planted. They also have not gotten any new flowers, so I have very few tomatoes. I planted them in large pots, don't know what kind of soil, but it may be a mixture of soil from my yard, potting soil, compost etc. It has been used previously for other vegetable plants. Should I fertilize them?
One key to understanding this kind of problem is to be aware of how tomatoes grow. The small fruiting types are nearly always vining types, that is they grow taller and taller (or rather longer and longer) without restriction while the conditions are right. They can always send out side shoots but there is normally always a growing terminal tip.
If you compare your red and yellow plants you may find that the red ones have a clear light green growing tip, where it looks like new small leaves and even tiny clusters of flowers are forming. The problem is that due to growing conditions that tip might not be formed - instead you get a much larger cluster of flowers or just leaves, with no cluster of infant growth. Without that growing tip the plant just seems to stop.
Fortunately there is an inbuilt protection mechanism - side shoots. Again looking carefully at the plants you may see small shoots growing where the leaves join the main stem. These are capable of carrying growing tips that can take over from the terminal tip that has gone "blind". If your examination coincides with my story then the solution is to make sure that at least one side shoot is allowed to grow to take over the vining expansion. There will be a temporary setback but the plants will recover.
I have seen the same thing happen to some of my tomato plants; I have put it down to a cooler than normal spring and my overly hasty planting out.