Stems are finely hairy when young and become smooth or furrowed as they mature, at times with peeling or shredding bark.

It is described as "sometimes rhizomatous", suggesting that it can reproduce from rhizomes, although this has not been described in the literature.

In one study, seedlings emerged from spring-collected seed-bank samples from old-growth plots, but in another, no Pacific rhododendron seeds were found in the soil seed bank.

Greenhouse studies of other rhododendron species found that any direct sunlight or a dry soil surface easily killed young seedlings.

Sprouting individuals grow well in full sun after canopy-opening disturbance.

It is an early-seral species in California but may dominate the understory in late-successional forests elsewhere. On other sites, its cover peaks during early to mid-succession before declining as the canopy closes.

Experimental seed heating treatments suggest that Pacific rhododendron seeds are sensitive to heat especially in wet soil.

Plants can bloom profusely in openings and on forest margins, but increased seed production has not been observed directly.

However, it may not be sensitive to fire of any season because it tends to sprout after being top-killed by fire of all severities.

Pacific rhododendron occurs in plant communities with varying stand structures and fuel characteristics. Dense thickets may carry fire through forest openings or act as ladder fuels. However, these effects reflect stand structure, not the species’ inherent flammability.

On some sites Pacific rhododendron is among the first plants to appear after fire. However, its recovery may be slower than immediate postfire colonizers such as Ceanothus species.

For example, in frequent-fire redwood forests, fire exclusion has resulted in a tall, dense understory of Pacific rhododendron. Whereas fire exclusion may have minor effects in forests with infrequent fire (e.g., North Pacific forests).

Where prefire cover is sparse, burning may eliminate it, but burning generally only reduces Pacific rhododendron cover temporarily.

At the southern edge of its range, modeled fire intervals ranged from about 9 to 30 years; in other forests, modeled intervals ranged from about 80 to 650 years.

At the southern end of its range it grows in forests with frequent, low-severity fires, while elsewhere it grows in forests with infrequent, mixed-severity or stand-replacing fires.

Modeled historical fire regimes range from frequent, low- to mixed-severity regimes (group 1) in southern forests, to moderately frequent mixed-severity regimes (group 3), to infrequent stand-replacement regimes (group 5) in wet coastal and high-elevation forests.

These conditions exceed those found under historically frequent fire regimes.