What Can I Do for Moss on Bushes?

Evaluation

• When moss grows on the bark of trees or shrubs, it's an indication of cooler temperatures, high ambient humidity and soil moisture, as well as diffused light. In a woodland setting, it's not unusual to naturally have clumps or sweeps of moss growing on rocks, logs or the bark of woody plants. Moss can be an indication of potentially saturated growing conditions, especially if algae appear in tandem, or that the vitality of the tree or shrub is deteriorating due to soggy soil or a fungal infection.

Physical Control

• Moss by itself isn't a concern in the garden if it doesn't pose a safety hazard. Mosses do not harm the shrubs on which they grow; it's more of an aesthetic issue. Physically wiping or scraping off moss from shrubs is the easiest and safest means of eradicating it. Then modify the growing conditions to make them less conducive for moss growth, such as reducing irrigation or increasing direct sunlight and air circulation. The best time to remove moss from shrubs is in winter when the shrub is dormant. This diminishes any damage to growing shoots or sprouting buds during the removal process.

Chemical Treatment

• In gardens with shrubs that are heavily festooned with moss, chemical control may be a viable option. However, because the chemical products used to kill moss are quite toxic and require specialized safety equipment or precautions, chemical treatment should be used only if physical or cultural control isn't successful. Copper sulfate and lime sulfur are two products that kill mosses and algae in gardens. These chemicals do not prevent moss growth; so if the garden conditions do not change, mosses may regrow and appear on shrubs again.

Recommendations

• If the health and appearance of your garden shrubs are not impacted by the presence of moss on the ground or their trunks and branches, you may not need to do anything. Monitor the garden and shrubs throughout the year, noting if moss growth is more prominent in certain seasons. The shrubs may deteriorate for reasons other than the presence of moss, which indicates high moisture levels in the landscape. If the shrubs are not naturally tolerant of high humidity, shade or overly moist soils, they will deteriorate. Correct the growing conditions in the garden around the affected shrubs if you want to diminish or eradicate moss. Physical and chemical controls are secondary solutions.