Iris reticulata is one of my favorites because it's one of the first bulbs to bloom in the spring. It is ephemeral, so it is ideal for a bed where you plant annuals or a perennial garden emerging later in the spring to hide the fading foliage and fill the space.
It is a perennial bulb that spreads by offsets. To rejuvenate the bed, dig up the bulbs every 3-5 years, break up the offsets and re-plant them about 3” deep and 3” apart, amending the soil with compost and/or grit to promote good drainage. I have not had a problem with squirrels digging out the bulbs. Good companions are Crocus, Snow Drops and Siberian Squill.