We have good fertility recommendations for various areas in the East on the resources tab.
A recent Bizarro comic has a great reference to broccoli’s ability to use fertilizer.
(c) Dan Piraro Used by permission.
We are not in cahoots with the “National Board of Broccoli Producers,” so broccolini is a fair stand-in at the Eastern Broccoli Project.
One consideration is that broccoli can get too big, and get hollow stem. Growers harvesting in the heat of summer find that making the last nitrogen fertilization four weeks before harvest helps avoid the excessive burst.
Some early varieties are maturing in 50 days in the summer. If you do the math, that means the last nitrogen side dress or fertigation is just three weeks after transplanting. Putting on ~150 lb/ac of nitrogen without burning the plants takes some planning.