Q.cabbage is tall and growing yellow flowers
Not full. Tall and skinny. Should I trim flowers?
Cabbage growth is optimum when temperatures are 60˚ to 65˚F. Cabbage will bolt or send out flowers to set seed if they are exposed to temperatures below 45 degrees or exposed to extremely hot temperatures. Cabbage also needs even moisture supply during head formation. Fertilizer (8-32-16) will also give it a much needed boost. Since your cabbage has already bolted it is not likely to form heads. You should pull them up and try again.
For more information on cabbage head formation, please visit the following link:
https://www.gardeningknowhow.com/edible/vegetables/cabbage/cabbage-head-formation.htm