If you just can't wait another minute to put some color in your landscape choose a cheery member of the Violaceae family. They are no pansies when it comes to chilly nights. In fact they prefer cool weather and actually become "shrinking violas" when the sweltering temps arrive.
Go on, do it, but don't give in to the lure of the garden yet when it comes to setting out tender annuals and vegetables. Our typical last frost date is still weeks away.