The distribution of vireya rhododendrons in the wild is centered on the botanical region known as 'Malesia', an area of South East Asia encompassing the Malay Archipelago, the Philippines, Borneo, Indonesia and New Guinea and surrounding island groups. It is for this reason that vireyas are sometimes referred to as 'Malesian Rhododendrons', although nowadays this is not considered a strictly accurate term as a small number of the 300+ species in subgenus Vireya grow outside this region, extending as far as Taiwan in the north to Queensland, Australia in the south, and from India in the west to the Solomon Islands in the east.

One misnomer commonly used when referring to vireyas is 'Tropical Rhododendrons'. Whilst a few species, such as Rhododendron zoelleri, are found growing at low altitude or even sea-level, where a truly tropical climate prevails, the majority of vireya species are to be found at higher elevations of between 1000m and 2500m. Here, in the cool montane forests, many species grow as epiphytes high in the trees where there is more light available to them than on the forest floor and where the morning sunshine gives way to cloud cover, followed by rain later each day.

Higher still, on more open ground, other species, including the heath-like Rhododendron ericoides, can be found growing terrestrially at altitudes of up to 4000m. As night falls, the clouds disperse leading to a rapid drop in temperature and above 2000m it is not uncommon for frosts to form in some areas. Whilst in a temperate climate this could prove fatal, in their natural habitat the vireyas are unaffected. At such latitudes there is little seasonal variation, other than 'wet' and 'dry' seasons, and daytime temperatures stay relatively constant throughout the year allowing the plants to stay in active growth, which in turn minimizes any potential frost damage. Plants grown in temperate climes, however, enter a dormant state for several months each winter as both temperature and light levels fall, consequently increasing the plants susceptibility.

Vireyas from the mid-altitudinal range are generally considered easier to cultivate, requiring less heat than those from low-lying areas, whilst replicating the growing conditions enjoyed by the alpine species can be challenging.