Tulips of any sort can be left in the ground year round and they will come back year after year. They will have to be dug up occasionally and separated but not for a few years. The bulbs produce little bulblets that will bloom in a few years so they can get very crowded after a while.

Your blurb said perennializing, not perennial. Perennializing is simply leaving the bulbs in the ground and not digging them up after they bloom.

In order to have them bloom year after year you must leave the foliage until it browns and dies. Fertilize with bulb fertilizer when the flowers are in bud and again in the fall.

I plant in groups of 5 in a circle throughout the bed. When the flowers are finished I loosely tie them upright with a Velcro tie. Don't tie them tightly. Then I plant petunias around the bulb circle. When the foliage is done the petunias spread over the spot where the bulbs are. This serves a couple of purposes. It covers what would be bare ground and since it is the only place I plant petunias I always know where my bulbs are. This is good if I ever want to change their location.