This is my first year growing broccoli rabe (raab,rapini).

Unlike store-bought, my plants have lots of leaves but fairly few and spindly buds. The broccoli rabe I've seen sold in the farmer's market near me looks similar to mine, but the rabe in the supermarket has considerably more and larger buds.

Is there some trick large scale growers use to increase the number and density of buds? Some kind of pruning...? Special fertilizing regimen...?

Anyone out there growing broc rabe that compares well to store-bought?