Cardinals prefer sunflower seeds. To discourage blue jays, grackles and sparrows while simultaneously encouraging cardinals and mourning doves, try safflower seeds. Plant shrubs and trees such as mulberry, sumac, hackberries and wild grapes to attract cardinals to your yard.
Cardinals will eat mealworms in a small tray, according to the Minnesota Department of Natural Resources. A baby cardinal's diet is almost exclusively insects.
It is difficult for cardinals to feed from traditional bird feeders with perches. Place your birdseed in a tray feeder or scatter seeds directly on the ground to make it easier for the cardinals to eat.