Azalea x 'CAROLINA' Japanese hybrid azalea

When Carolina azalea comes into bloom, it is as if the shrub has dressed itself in a ceremonial kimono – large, widely opened flowers with a rosy to salmon pink center, white edging, and purple speckling resemble painted plates overlapping in the tiered structure of the plant. Its habit is dense but not heavy – moderately compact, with clearly tiered branches that give the shrub an elegant architecture. Flowering arrives in mid season, during May, about a week later than most Japanese azaleas, and it comes all at once, creating a spectacular effect that lasts longer than in common japonicas. And when autumn is favourable, it can surprise with a few extra blossoms in October and November, as if unwilling to accept the end of the season. The evergreen leaves are elliptic to oblong, leathery, with a gentle gloss and deep green colour that turns bronze in winter on sheltered sites.

The origin of Carolina is somewhat mysterious, with only one fact securely documented: it was exhibited at Windsor in 1950 and entered into the international register in 1958; breeder and parentage are not recorded. Practical experience shows it is not an “Indian azalea” – its proven hardiness in USDA zone 5b rules that out. Most likely it is an older European evergreen hybrid with satsuki (Rhododendron indicum) influence, which explains the longer flowering effect and occasional autumn blooms. Carolina thus stands between early japonicas and later satsuki types and can be regarded as one of the pioneering stepping stones toward “late” hybrids, whose deliberate breeding was initiated in the United States by Robert Gartrell as early as the 1930s and which later became famous as the Robin Hill hybrids.

In the garden, Carolina behaves like an elegant actress who demands a good stage and the right partners. Thanks to its structure and striking blossoms, it shows best in semi shaded areas among larger shrubs or trees, where light filters through but it is not exposed to full sun all day. It combines beautifully with other evergreen azaleas and rhododendrons, but also with spring bulbs that bow out just as Carolina takes the stage. It looks splendid alongside ferns, non-variegated hostas, or shade loving grasses that emphasize its delicate architecture and add layered character to the planting.

Evergreen azaleas require light, acidic, very well drained soil that is preferably kept constantly moist but never waterlogged, and rich in iron and phosphorus. Use special fertilizers for rhododendrons and azaleas, or more generally for ericaceous plants. To preserve soil moisture, it is best to keep them mulched at all times, ideally with bark or leaf mould, which also protects their shallow roots from overheating and drying out. An ideal planting mix is one third peat, one third well rotted leaf mould or non limed compost, and one third of the site’s own garden soil, preferably sieved. Azaleas form shallow, spreading root systems, so never plant them deeply and never in heavy, impermeable soil. The best location is partial shade or filtered sunlight beneath tall tree canopies; they can tolerate full sun only for part of the day if moisture is sufficient. Carolina’s hardiness has been tested down to –27 °C (USDA zone 5b), and the plant can also be grown year round in broad but not overly deep outdoor containers, provided they are insulated against frost. In containers, however, occasional watering is essential, as the substrate dries out faster than in the ground.

Last update 18-12-2010; 19-09-2025