Preheat oven to 425°F.
Clean and slice rhubarb and combine with blueberries in large bowl.
Mix sugar and flour together in small bowl.
Add sugar and flour mixture to fruit and stir to mix. Let the fruit mixture sit for about 10 minutes so the juices release.
Pour the filling evenly into the crust.
Roll out additional pie crust and place on top of fruit. Do pie crust art if you’re in the mood. You can also do a lattice top crust, or if you prefer, a traditional double crust pie.
With a double crust, be sure you pinch the edges to make a tight and pretty border, and cut some slits in the top to allow steam out.
Bake at 425°F for 10 minutes. Lower temperature to 325°F and bake for an additional 40-50 minutes. Fruit and juices should be bubbling around the edges.