Moss Myths and Misunderstandings

Six facts about moss growth, and how to view this plant.

As I walk through Cape Cod’s beautiful conservation areas in the winter, I am constantly admiring the moss. In areas that are brown and dormant, the moss glows in various shades of green, from a pale lime to a vibrant emerald. And when the temperatures rise into the 40’s, especially after a rain, the moss swells and shines even brighter. It’s a beautiful, non-flowering plant that often doesn’t get the respect that it deserves. Moss can also give us information about our landscapes, so in this blog we look at some misunderstandings about these plants that thrive on the Cape.

1. Complaint: “It keeps coming back!” The most common moss complaint we hear from our customers is that it’s taking over their lawns. “What I hear from people the most is ‘Moss never goes away! I kill it and it comes right back.'” says Jamie (“Dekes”) Dedekian, one of the lawn experts at Hyannis Country Garden. “What they don’t understand is that the moss isn’t the problem. It’s an indicator of the program,” Dekes continues. “Moss is going to grow where the conditions are right. If you want to get rid of the moss, you’ll need to change those conditions.

In Cape landscapes, the three conditions that encourage moss are compact soil, frequent irrigation, and shade. Moss will thrive in any of those environments, or a combination of those conditions. “If you change the environment,” Dekes says, “you’ll change the plants that grow there. So if you want to get rid of the moss you’ll need to change the compactness of the soil, the fact that you’re watering too frequently, or the amount of shade in the area.” Killing the moss won’t get rid of it permanently; you’ll only do that by addressing the conditions that encourage the moss in the first place.

2. Myth: Moss in the lawn means you need to add lime. False. Moss is happy to grow in alkaline areas or on acidic soils. While it’s true that turf grasses prefer a neutral pH for optimum growth, moss isn’t that picky. By all means have a soil test, and adjust the pH for good grass growth, but liming alone won’t address the moss. In order to get rid of the moss, and to have a thicker lawn, you’ll need to address the conditions that favor the moss in the first place: compact soil, moisture, and shade. (Note: it’s also perfectly acceptable to decide that the moss is the better plant in parts of your yard, and allow it to take over. It’s your yard, and your choice about what you want to grow there!)

3. Myth: Moss only grows in damp places. Although moss loves regular moisture, and will spread faster in such conditions, it’s actually quite drought-tolerant once it’s started to grow. Moss tolerates a wide range of temperatures and levels of moisture…this is a very adaptable plant!

4. Myth: Moss only grows on the north side of trees. You’ve undoubtedly heard that if you’re lost in the woods you should look at the base of trees, because moss growth will tell you which direction is North. Unfortunately, if you try that on Cape Cod you’re likely to be walking in circles forever. Although moss loves the shade, with the right conditions it will grow in the sun as well. In most Cape woodlands you’ll see moss growing all around the bottom of trees. North, South, East or West, moss will thrive where moss grows best.

5. Misunderstanding: The pale green on rocks and trees is another kind of moss. Those pale gray-green growths that you see on trees, rocks and even the forest floor are lichens, not moss. Lichens are algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship. They range from the fuzzy “old man’s beard” lichens we see on so many trees, to the flat lichens that are on rock walls and even on the shingles of our houses.

6: Misunderstanding: Moss is a problem. The moss itself isn’t a problem, but our perception of it might be. If it’s growing in areas where we don’t want it to be, we need to change the environment. If you have moss in your perennial garden, for example, and you don’t want it there, top-dress that garden with compost or composted manure and then top with an inch of mulch. Notice in the woods how the areas that are “mulched” with the fallen leaves and pine needles don’t have much moss. Instead, the moss is growing on logs, rocks or the base of trees, away from that organic layer. You can emulate these conditions in a perennial garden by topdressing with compost and bark mulch on a regular basis. This improves the soil structure from the top down.

“It’s interesting,” Dekes likes to tell our customers, “that moss and crabgrass, two plants that our customers fight, like the same conditions. They both do well on compact soil. Crabgrass grows in such places in sun, and moss in sun or shade, but it’s the hard ground that provides the perfect growing conditions for both plants.”

The takeaway for our customers is to appreciate the moss in some areas of your yard, gardens and the wild spaces, but if it’s growing where you don’t want it, change that environment so it’s better suited for other plants.