Given the larch is a deciduous evergreen, any understory or nearby plants should be deciduous as well so needles do not cause a problem. You might consider on of the cultivars of Sumac for its contrasting leaves to the evergreen needles and outstanding fall color. Other choices would be plants from the Viburnum family. They have outstanding flower shows, an edible berry for the the wildlife and great fall colors. These are just a couple of examples. Be creative and also consider using perennials there for some summer color and additional foliage variation.
