You can plant all kinds of things in Strawberry and Herb pots......Heucheras seem really happy in them, I guess it's the good drainage. You can position the pot so that the shade lovers are on the shady side and the........well you get the picture.
In my example I've used a rainbow of colours but the simple use of two colours might look better, or perhaps add some other plant into the mix, maybe a Hosta or two.
I used a coarse compost that had loads of stringy stuff in it, this helped hold the compost from sneaking out at the sides of the plant.....take a bit of care watering until the Heucs are rooted, you don't want to flush the soil out of the planting holes.
Watering is easier if you plonk the whole thing in a shallow saucer, the terracotta will wick the water up and ensure that the bottom plants grow as well as the ones at the top.
You could add some crocus bulbs, they would flower at the time when Heucheras are not looking their best and so keep the pot looking pretty.