The only patch of grass which I have not replaced with flowers or evergreens is a 20 foot by 20 foot sunny plot in front of my house.  Next year I want to remove that grass, plant a serviceberry tree, and surround it with some low groundcovers that would look presentable. Which groundcovers might serve?

With such a large area, a variety of groundcovers would be advisable to create plant diversity and interest.  Keep in mind that as the serviceberry tree grows, the light conditions in that area will change.  Therefore, plants that will adjust to increased shade should be placed closer to the tree.  These include wintercreeper (Euonymus), plumbago (Ceratostigma), Ajuga, and bearberry.

Farther away from the tree where more sun is likely, even as the tree grows, try sedum as well as some of the low growing junipers like ‘Blue Rug’, ‘Blue Chip’, ‘Calgary Carpet’, or ‘Procumbens’ (dwarf).

Remember also that when spaced properly, several perennials and shrubs can cover the ground as a dense mass, while providing additional height and textural interest. Perennials in this group include: Astilbe, catmint (Nepeta), coral bells (Heuchera), daylilies, Geranium, Hosta, lamb’s ears (Stachys), lavender, ornamental grasses, Rudbeckia, and Salvia, just to name a few.  Shrub varieties include: Cotoneaster, Deutzia ‘Nikko’, Forsythia ‘Gold Tide’, Meidiland roses, Potentilla, Spirea, and gro-low sumac. Again, don’t be afraid to mix your plantings to make them more interesting and enjoyable.

Related: Why doesn’t my serviceberry shrub (Amelanchier canadensis) ever produce berries?