Every once in awhile, we will have a customer ask us about something that is growing on their tree's trunk or a shrub's branch. And often, when they ask, it is in late winter, which is when lichen is at its brightest, color-wise.
Lichen are common and grow on many trees and shrubs. They are a mixture of fungus and algae in varying colors of orange, yellow, white, blue-grey, and blue-green. They are especially noticeable, as we mentioned, in January, February, and early March (cool, wet weather); they are at their most colorful. They often grow as patches on the bark of a tree.
Lichens grow in many interesting forms. They can be flattened and crusted in appearance, can have raised leaf-like lobes, or can have branched thread-like growths.
Lichens grow on any undisturbed surface, including wood (such as fences), bark, rock, soil, and more. They're considered an indicator of good air quality and therefore are not usually found in industrial areas. They rarely grow on rapidly growing trees and shrubs- this is probably because the rapid growth makes the bark shed before the lichen has a chance to grow.
In the garden, they are usually found on slow-growing trees and shrubs (if they're found at all), especially more mature, older trees. They can also appear on declining or less vigorous trees or shrubs, however, they do not damage plants, and therefore no damage control is necessary.
Although lichens do not need to be removed on trees and shrubs, they do need to be removed on garden statues, fountains, and other garden sculptures. The reason to remove them from these items is because, over time, the lichens can penetrate and damage the stone. To remove lichens on these items, we recommend using a spray that has copper salts.
Some interesting facts about lichen:
Ruby-throated hummingbirds line their nests with strips of lichen
Lichen absorb nutrients from the air and are an indicator of healthy air quality
Approximately 8% of the earth is covered in lichen!
Lichens have been used historically to make dyes and medicines
If you are unsure if what's growing on your plant is lichen or something else that could damage your plant, please ask us at the nursery!