First of all, welcome! I don't grow poppies so I really can't help you much. But try googling up the topic. Now, I assume the poppy you have is an oriental poppy? Do you mean a bare root plant (as in a palnt with roots but without soil) or root cuttings (roots which have been cut off to produce more plants)? If you are planting root cuttings, this is what Vesey said on their site:
Hardy in zones
The plants go dormant in early summer, so plant them near a later blooming perennial, like Echinacea or Gypsophila, or summer-blooming bulbs. (New foliage emerges in fall.) Poppies thrive in any well-drained soil and full sun. Space plants 15"-18" apart with the crown (the point where the roots meet the shoots) just under the soil surface. Deadhead after blooming.