What is your opinion on algae and lichens within the garden? Are you trying to discourage them or are you one of the select few who promotes their growth? Let me introduce you to these algae and lichens so that you can make an informed decision.
Algae in glasshouses and polytunnels
Algae are the much-maligned green slimes found on ponds and as a greenish scum on paths and drives. You may be surprised to know algae is a garden plant, albeit a stem-less and non-flowering specimen. Over winter, disgusting grayish-green algae often builds up on the inside glass of our garden sheds, glasshouses and polytunnels. The solution is to trim back any surrounding planting to allow as much light as possible to enter. Also, try to leave the doors and windows open for a few hours each week to prevent the build up of stagnant air. If some of the slightly powdery scum still builds up, you can wipe it off the glass with a mild detergent, whereas on polytunnels only wipe the plastic with warm soapy water.
Algae control on steps and paths
Algae and mosses often coat paths and quite dangerously garden steps; damp shade is again a significant factor. Reducing shade will cut down on some algae and moss forming; by increasing the access of sunlight, you will also reduce dampness. The application of a copper sulfate solution (commonly known as bluestone) is a time-honored and effective way to combat algae on paths. When applied correctly it has a residual effect that prevents regrowth for up to several years after treatment. Mix copper sulfate or “bluestone” at a rate of 10 grams to 10 liters of water in a plastic container. Apply on a dry day, brush in, and then leave it three weeks to act on the algae. After three weeks brush again with a stiff bristled brush and “hey presto.” When applying any algae or moss control solution remember to avoid drift onto surrounding lawns, plants and vehicles. Use protection equipment when using chemicals including a mask with a dust cartridge, safety goggles and impervious gloves with overalls. Remember, Apply all chemicals according to the manufacturer’s instructions and heed those safety warnings.
Lichens in the garden
However, what happens when this alga teams up with a fungus and the two start to live in a mutually beneficial association or symbiosis? Well, in that situation you get a plant form known as a lichen. A situation where lichens grow in abundance is on old carved stone headstones in graveyards. Many of the age-old stones will display white growths often containing bright yellow or orange splashes.When I have occasion to attend a funeral in a cemetery, I am always struck by the contrast between the mourner’s dark garb and the pings and flecks of white, yellow and orange lichen growth. These growths are the lichens, growing where other plants would falter. Lichens are tough devils if there were an SAS for the plant world they would be the first to enlist.
Growing your lichens
I feel lichens have a place within the garden; they happen to be an accurate indicator of low pollution, no harm in that. Lichen growth also adds a considerable amount of character to feature rocks, boundary walls, terracotta containers and stone garden sculptures. If you would like to encourage this type of growth, try this recipe for “lichen slurry.” Mix one tablespoon of ground up lichen to one pint of natural yogurt or buttermilk and mix well. Paint or dab this slurry onto the object you wish the lichen to grow on, sit back and be prepared to wait, as fine-looking lichen growth is quite slow to form. But, worth it.