Companion plants for Sweet Woodruff
Sweet Woodruff blooms from May through June. It wants full shade and moderate water. The 8 companion pairings below each state why the pairing works.
Taking over as Sweet Woodruff finishes

Northern Sea Oats
Takes part shade to full shade and moderate water; blooms in midsummer as this one finishes; taller at 3.5 ft, for the layer behind it; its seed heads stand through winter, for structure and the birds; this one spreads, so it will crowd its neighbor in time.

Summersweet
Takes part shade to full shade and moderate to high water; blooms in midsummer as this one finishes; stands well above at 6 ft, a canopy to plant beneath; its white flowers settle the white.

Ligularia
Takes part shade to full shade and moderate to high water; blooms in midsummer as this one finishes; taller at 4 ft, for the layer behind it; a soft color beside the white; this one spreads, so it will crowd its neighbor in time.

Goatsbeard
Takes part shade to full shade and moderate water; overlaps, then carries the display into midsummer; taller at 4 ft, for the layer behind it; its white flowers settle the white; this one spreads, so it will crowd its neighbor in time.
Blooming alongside

Azalea
Takes part shade to full shade and moderate water; opens in mid spring and overlaps into this one's season; taller at 4 ft, for the layer behind it; evergreen, so the bed keeps its shape through winter.

Camellia
Takes part shade to full shade and moderate water; blooms in midwinter, before this one opens; stands well above at 6.5 ft, a canopy to plant beneath; evergreen, so the bed keeps its shape through winter; they only overlap in zones 7 to 8.

Pachysandra
Shares full shade and moderate water; opens in mid spring and overlaps into this one's season; evergreen, so the bed keeps its shape through winter; its white flowers settle the white.

Ostrich Fern
Takes part shade to full shade and moderate to high water; taller at 4 ft, for the layer behind it.