Samolus porosus is a water loving plant found in moist or in permanently wet places in coastal marshes, seeps and cliffs from Namaqualand to KwaZulu-Natal.

Samolus porosus grows in clay and loamy soils in full sun, lightly shaded areas and even heavier shade. It is often found colonizing the edges of estuaries even where the water is subject to tidal influences and is therefore brackish. It may form dense colonies, and with its vigorous rhizomatous growth helps to stabilize water edges, thereby helping to reduce erosion.

It is also common on south-facing cliffs along the southern Western Cape coast where it latches onto mud flows or colonizes peaty crevices. In this environment it often grows as a single plant or as individuals scattered across the cliffs where it can find suitable purchase. These environments are shaded and only receive short periods of direct sunlight, particularly in summer. Samolus porosus, in this environment, grows softer reaching for better light, and although initially erect, its etiolated stems often cascade from the cliffs.

Samolus porosus grows wherever there is permanent seep and has the habit of colonizing erosion or drainage ditches where water accumulates. It may be found in such ditches along forest margins where it produces an abundance of soft, tangled and cascading branches. When these plants are flowering they look very similar to Gypsophila paniculata , the florist plant commonly known as baby's-breath.