Anti slip Driveways Paths and Patios

The effects of algae, moss, lichens and liverworts

Algae and algae-like growths: A green film or powdery deposit is typical of algae on paving, stonework and garden furniture. The dark green or blackish jelly-like growths that often appear in damper, cooler weather on paths and areas of tarmac are incorrectly known as blue-green or gelatinous algae, but are in fact a cyanobacteria called Nostoc.

Lichen: These are common on paving and timber structures such as garden benches. The colour of lichen varies with species, but most are silver-grey, grey-green, yellow or orange. They can be crust-like, leafy or scurfy in texture.

Liverwort: Liverworts that grow on hard surfaces usually have a green, flattened, plate-like body and no leaves. A common example is Marchantia, which is often topped with umbrella-like structures carrying sexual organs.

Moss: Mosses commonly found on hard surfaces are usually cushion-like.

In July of last year the Royal Horticultural Society put some information on their site

If growths of algae, moss, lichens and liverworts are of no hazard  ( this may not apply to  driveways paths and patios) then they could be left to allowed to flourish.  It may help to  develop your garden.  It can  give the impression of a mature garden and possibly serve to enhance visually.  It could potentially ensure longevity of some very rare species of lichen.

Algae, lichens, liverworts and moss can grow on most surfaces such a concrete, tarmac, block paving and paving slabs.  They do not however damage what they are growing on  but can cause patios, driveways, paths and steps to become quite slippy.

They can be quite hazardous.  With our ever changing climate build-up can occur during any wet period. Areas which are shady, sheltered, poorly drained or humid. They need moisture for both growth and reproduction so damp places are a prime area.

Lichens and moss can be deemed to be attractive on stone and timber surfaces and can  give a mature look to the garden.  It is said that they do not harm the surfaces on which they grow and can be a natural part of your gardens development.

Lichens are particularly common in areas with clean air. They are slow to spread  as they only grow very slowly  and are slow to spread.

Solutions

The solution to algae, moss, lichens and liverworts

If you have block paving or paving slabs  remove the moss by running a sharp tool along the cracks. Alternatively, use a block paving brush with a long handle, narrow head and wire bristles for effective cleaning without stooping.

A pressure washer or jet wash will get rid of the moss and algae.  But use with care where drainage is an issue as it could make damp problems worse.

Brush hard surfaces with a stiff broom on a regular basis to help prevent growths from taking hold. Raking loose surfaces such as gravel helps to keep these areas free of both moss and weeds

Improve air flow where possible this will allow the drying effects of sun and wind to reach the problem area

Ensure surfaces slope slightly to prevent standing water  if not try and Improve drainage in the local area.

Only pave areas essential for access.

When constructing new hard surfaces ensure the drainage is considered and  installed if necessary.

Keep drains clear of leaves and debris

Surface finishes that are raised to give grip in wet weather are ideal for shady spots.  Resin Bonded Gravel is an option as this has anti slip qualities.  It also uses the existing surface whether it is concrete and  tarmac  (paving slabs or block paving if it is for foot traffic)

Algae, moss, lichens and liverworts can be removed with most proprietary patio cleaners. Most products are non-persistent and repeat applications will be required.

Use products based on benzalkonium chloride, pelargonic acid, acetic acid or nitrilo triacetic acid/trisodium salt which claim to control moss and algae on hard surfaces or natural paths. They may also give some control of lichens.

Just Patio and Concrete Cleaner is a natural surfactant (detergent) based on seaweed extracts and should be especially safe to use near planted areas. It claims to remove algae on hard surfaces

Path and patio cleaners based on hydrochloric acid or bleach have some effect but are not recommended for use near plants. They can also discolour certain types of stone.