It needs to be made clear that only seedling grown juvenile plants will climb. This applies to all the climbing Metrosideros species. Their preferred substrate is tree fern (like wheki or mamaku), but will grow up a stone or concrete wall. This, and M. fulgens, are perfect substitutes for ivy (Hedera helix) which is an ecological hazard and should never be grown (ivy should, at the very least, be declared a surveillance pest plant).