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TREES & plants

Plants of Acid Soil

Rhododendron plants in our Plants of Acid Soil Collection
The heath (Ericaceae) family contains many highly ornamental garden plants including rhododendrons, azaleas, heaths, and heathers. Because the members of the family naturally occur in areas where soil pH is low (below 6.5), they are acidophiles, meaning acid-loving plants.

Plants of Acid Soils was established by modifying calcareous soils (typical in the Midwest) on The Morton Arboretum grounds. The staff worked with the American Rhododendron Society, Midwest Chapter, to create a rhododendron test bed where many desirable and recommended varieties for this region are featured.

Rhododendrons and azaleas are the dominant group in this collection and are represented by more than 67 kinds. Arboretum staff evaluate and promote desirable rhododendrons for Northern Illinois. The rhododendrons in this collection put on a spectacular display in spring.

In winter, the hollies (Ilex) steal the show with their evergreen leaves and bright red fruits. The blue hollies are extremely cold hardy and have lustrous dark green leaves, providing dramatic backdrops for their bright red fruits.