Best Plants Under Big Trees
'PJM' rhododendron (Rhododendron 'PJM') An understory shrub that grows up to 4 feet tall and wide, 'PJM' is one of the few rhodos that grows well in the alkaline soil common in many parts of the Midwest. Clusters of lavender flowers stand out against shiny, dark green leaves. To Zone 4.
Pictured: Rhododendrons flourish under trees at the Holden Arboretum in Kirtland, Ohio.