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Flame azalea illustration

Azalea Border plants

Flame azalea


Fun Facts

  • Korean rhododendron (Rhododendron mucronulatum) is an early-blooming species and is usually the first rhododendron in Azalea Border to bloom each spring. It bears bright lavender-pink flowers that open before the foliage emerges.

  • The Ghent azalea hybrids (Rhododendron × gandavense) bloom in May, displaying a patchwork of flower color among its cultivars and unnamed hybrids. This hybrid group has multiple Rhododendron species in its parentage and originated from plant breeders in Belgium in the early nineteenth century.

  • Coast azalea (Rhododendron atlanticum) has especially fragrant white to light pink flowers and bluish green foliage. Coast azalea is native in the mid-Atlantic and southeastern coastal states where it grows as a twiggy, low-growing shrub in forest understories.

  • Autumn along Azalea Border is also a treat once the katsura trees (Cercidiphyllum spp.) begin to senesce and their leaves change color to yellow and light orange­—at this stage the leaves have a pleasant fragrance often compared to the aroma of baking bread and caramelized sugar.


Initially designed by noted landscape architect Beatrix Farrand [pdf] and installed in 1946, this collection of Rhododendron and other members of the heath family (Ericaceae) featured masses of shrubs grown mainly for their ornamental merit. Over time, however, some plants thrived while others perished due to a high water table, prompting a curatorial review and renovation in 2007. The collection continues to feature striking ornamentals, but also offers a destination for accessions of wild provenance—particularly plants that prefer “wet feet” like Rhododendron viscosum and R. atlanticum, the swamp and coastal azaleas, respectively.

Each bed within Azalea Border tends to have a prominent backbone species or genus (e.g., Rhododendron arborescens, Enkianthus), with ancillary species and cultivars mixed in. The midsized serviceberries (Amelanchier spp.) are understory species grown in many of the beds; they serve as a thread tying the beds together, particularly when they are all in bloom. The overstory comprises mostly maples, including the Arboretum’s tallest deciduous tree, a silver maple (Acer saccharinum) standing at a height of 104 feet. Notable specimens of katsura (Cercidiphyllum japonicum) and cork trees (Phellodendron amurense) can also be found here.


Featured Plants

Illustration of Cercidiphyllum by Charles Faxon
882*A Map it ↗

Katsura Tree

Scientific Name
Cercidiphyllum japonicum

The Arnold Arboretum’s oldest katsura arrived as seed in 1878. The story of how it came here is the opening of long series of exchanges between the Arboretum and researchers in Japan.

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Form of katsura from distance, showing red haze of spring flowers

Plants in this Collection

Plant ID Accession Date Received As Origin Source

Featured Walk

This quarter-mile tour through the Explorers Garden features stories from the Arboretum’s century and a half of collecting plants around the world. If you’re at the Arboretum, click here to take a version of this tour with Expeditions, our mobile web app.

Dove tree (Davidia involucrata)

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