How do I grow large cabbage heads?

How do I grow large cabbage heads from such seedlings?
It's very simple!
Cabbage is responsive to organic and nitrogen fertilizers when it starts growing.
So we're going to use nitrogen for the first fertilizing.
Nitrogen fertilizing can organic (for example, chicken droppings) or mineral (any saltpeter, urea, or ammonium sulfate).
Do this to increase the leaf surface and the head weight.