On Mount Kilimanjaro, which is mostly arid, Subularia monticola grows in oases made by rain or melted snow collecting in depressions, where it forms continuous carpets of vegetation alongside Eriocaulon volkensii, Cyperaceae and Bulliarda elatinoides. On Mount Kenya, cracks formed by daily freezing and thawing of ice provide a refuge for Subularia monticola seedlings. It also forms short, dense mats on the occasionally flooded mudflats around Lake Kimilili, a lake 4150 meters above sea-level on the Kenya-Uganda border.