Hi RR, Blood fish and bone is a slow release balanced fertilizer..With an NPN of roughly 555.. This lasts a lot longer in soil than say dried blood alone ..
Dried blood is a quick release easily absorbed nitrogen fertilizer with a NPN roughly of 12-0-0 ..
It's the quick release high nitrogen fertilizers that give cabbage etc a boost ..
Other high nitrogen fertilizers are Sulphate of ammonium ,Nitrate of soda ..
High nitrogen wouldn't be suitable for seedlings etc..
The way I apply it is just sprinkle a little around base of plant and water it in well ..