Moss can flourish in the most uninhabitable of areas such as brick walls, bare patches of lawn, cracks in tarmac. The success of its many species is largely due to its size, design and adaptability.
Mosses are primitive plants that lack vascular tissue which, in other plants, conducts water and also provides support. Therefore, moss needs to remain small to keep itself hydrated and to support the weight of its stems. This has brought its own success as over 22,000 species of moss can survive in small microcommunities, such as between paving slabs, on the top of a brick wall, in cracks of tarmac driveways, in bare patches of lawn, around tree roots.
The type of chlorophyll in the leaves of moss can absorb light in shady areas so it can grow in areas that are uninhabitable to other plants. Lying flat, moss can take advantage of the microenvironment of a surface warmed by the sun with little air flow, rather like in a layer of insulation. In addition, moisture evaporating from the warmed surface creates a humid zone where moss can flourish. On decaying surfaces such as a log, increased levels of carbon dioxide provide the essential material for photosynthesis. The dense texture of moss slows down air flow and reduces water evaporation even when conditions are less than favourable. In dry periods, moss will rely on dew or condensation when the warm surface cools overnight.
When it comes to the time to reproduce and spread, the spores of moss need to escape from this safe and protective environment so mosses elevate their spores in capsules on long stalks or setae to catch air currents for dispersion. This is the period when moss needs to be tackled before it spreads and it is often evident when the sun lights up the carpet of moss and stalks, rather like blades of grass on fire. A systemic biocide such as Baticlean CR should be left on the surface to kill spores. Hydrosil BS can be applied on a clean surface as a water repellent as moss cannot survive without moisture.