Have you ever noticed masses of light-green, plant-like material growing in your lawn while mowing your grass? These are probably patches of moss or algae.
Most people notice moss during the summer months when they are actively cutting the lawn. However, winter months, between December and March, are the best time to control your moss problems.
Following are some tips to keep your moss and algae issues under control.
The key to controlling any plant is to know its life cycle and its favored conditions. Mosses are small, non-parasitic plants spread by spores. They have many thread-like stems with tiny leaves, and they form thick mats on the soil surface. Mosses do not kill turf grasses, but rather fill in the space in areas where conditions are poor for grass development. They are known to thrive in shady, wet areas.
Algae are simple, plant-like organisms that form a thick mat or ‘scum' layer over the soil surface. They are usually green, but also appear in brown or red varieties.
Algae need high amounts of moisture to survive. Like mosses, they don't actively attack turf grasses, but rather grow in the areas where turf won't.
Mosses and algae like to grow in places that are not conducive to healthy turf grasses. They like sites with: Compacted soil, poor drainage, highly-acidic soil, low soil fertility, dense shade and heavy irrigation.
Controlling mosses and algae long term means correcting these conditions in your yard.
Lightly-compacted soils can be treated by using a core aerator to take small plugs out of the soil and increase drainage.
If the area has little grass to begin with, it is best to renovate the area. Use a tiller to break up the soil down to 6 inches. Use this time to incorporate fertilizer and lime according to the results of your soil test. The new turf will grow much better with proper soil acidity and fertilization.
You can also improve drainage by re-contouring any low spots in the affected area. In extremely wet areas, you may need to install drain tiles to rapidly drain excess water. Organic matter can be added to the soil which will improve drainage. If you have an irrigation system, cut it back in areas with moss or algae growth.
Because mosses thrive in dense shade, pruning tree branches may be necessary to improve sunlight and airflow.
However, this is a limited technique. In most instances, only small amounts of pruning can be done without affecting the overall look or health of your trees.
If heavy pruning is not an option, you may need to consider using a shade-tolerant ground cover. You may also choose to mulch large areas under your trees, which discourages moss and algae growth and is great for tree health.
There are also several chemicals labeled for moss and algae control. Iron sulfates and potassium salts of fatty acids can be found under various brand names at most garden centers and feed stores. Always read and follow instructions found on the label.
Please note that chemicals will only help temporarily. The most effective control is altering your landscape environment to discourage moss and algae growth.
Clark MacAllister is the Dawson County extension agent. For more information, call (706)265-2442.