'Humboldt' is one of the most popular rhododendron hybrids in northern Germany but is rarely seen in Finland. Its cold hardiness is not quite sufficient, though it survives without great damage under snow cover.
‘Humboldt’ is an old T. J. R. Seidler hybrid, first seen in 1926. Its parentage is unknown except that R. catawbiense is somehow involved.
The violet buds produce pale violet flowers whose upper petal has a darker blotch.
In Germany it reaches over 2m but in Finland only about 1m, kept low by heavy snow and also due to frost damage. At Mustila ‘Humboldt’ has remained low, stretching its branches out along the ground, which means good winter protection and good flowering.