When I first started building ponds, I was told that moss has been tried and just doesn’t work in our waterfalls. This may be exactly the reason I was determined to find a way to build with moss. Here are a few of the things I’ve come to understand about moss in my own oversimplified layman’s terms.
Moss Basics
Moss is photosynthetic, meaning it uses sunlight to make its food rather than getting nutrients from the soil. With no vascular structure, moss has no capacity to move water like other plants. Instead, it relies on direct contact with water, like a candlewick to oil. If you understand the different ways moss connects to the water and air, you have the key to keeping moss alive. The fastest way to kill moss? Allow air to circulate under it.
Aquatic moss grows completely under the water. Think of the stunning aquarium waterscapes. Most pond owners don’t appreciate this moss, as they think of it as nuisance algae, so we generally don’t install it. However, I look forward to the day when we overcome this misconception.
Bog mosses connect to water in a very plain manner. They sit in the edge of bodies of water and in many ways act as a conductor between water and soil. Sphagnum mosses are perhaps the most common of these types.
Bog moss can be started in a pond system by lodging a small piece between two rocks where there is low or no flow. It is a great way to edge a bog pocket (foam directly onto the water side of the pocket.) Sphagnum wants to be in 1 inch of water or less to start and then will form mats and grow out into the pond system. If you build a bog pocket at water level out of underlayment, fill it with wet peat moss and place a small piece of sphagnum in it. It will fill out the pocket in a season.
Avoid placing moss where it connects to water inside the liner and soil outside the liner. It will wick water over the edge of the liner at an alarming rate, creating a “leak” of sorts.
Terrestrial & Carpet Moss
Many terrestrial mosses are moisture adjacent. They can be confusing, as they have anchors opposed to roots and rely on a strong connection to the rich organic duff layer of the forest and rotting tree matter to keep them hydrated. Some terrestrial mosses are really easy to grow, as they adapt quickly to environmental changes. One of the easiest mosses to use looks like tiny pine trees and easily grows between rocks and crevices.
Carpet moss likewise can be used as its name suggests. It’s simple to grow, but it can overtake slower-growing moss.
Affixing carpet moss securely with a small amount of foam over the back of the entire piece is critical in making the connection between rock and moss. To do this, take a piece of cardboard or rock pad and foam an area the size of the moss. Gently dip the bottom of the moss into the foam just a bit and then affix it to the rock. I will often start a carpet in the water at or just below the waterline so it can wick moisture up the rock and stay hydrated. Air gaps under the moss are enemy No. 1. Terrestrial moss generally loves wet foam, though.
Mound & Rock Moss
I love spring cleanouts as they are the proving grounds for my moss work. What stayed and is thriving? What didn’t grow well? Why?
I’ll often mimic more difficult-to-grow mound moss by making a ball of foam, and later when the foam is dry, I attach a terrestrial moss to this shape as per the instructions above. For other more particular mosses, it can take time to learn their preferences for water and how to connect them properly.
Mound moss is one of the most difficult to grow, but stunning when you get the conditions correct. I’ve had the greatest success when the moss was harvested in small pieces from a property and then affixed to a rock that is in direct contact with the water right away.
Rock moss grows directly on a rock and absorbs condensation that forms on rocks. Many times, lichen will form first on a rock, and moss will take the opportunity to grow in the environment created by the lichen. Other plants will, in turn, be able to grow from the moss. Affixed by foam to a rock, rock moss is generally easy to grow.
The simplest way to add rock moss to a waterscape is by using rock that already has moss growing on it. The biggest mistake I see people making with this beautiful stone is using a lush moss rock for a waterfall weir stone and a plain rock for the shoulders. Moss growing on rock doesn’t want to be completely submerged (i.e., drowned). It just wants to wick water from the rock. By using the mossy rock as shoulders and the plain rocks as waterfall weir stones, you allow the moss to creep into the water at its own pace.
Moss Maxims
If you need to foam a gap or crack in your rock work and intend to disguise it with moss, first fill the gap and let it dry, leaving room for the moss. Then affix the moss with a small amount of foam. This way you won’t have chunks of foam pushing up through the moss.
Wild moss will often grow from a crack in a rock out over the rock face. Mimicking this often makes your moss work look more natural.
When gathering from the wild, never take an entire clump or completely clean off a decaying tree trunk or rock. It takes an incredible amount of time for moss to begin to grow on a surface. By harvesting some and leaving some, you allow it to multiply. To achieve carpets of moss in a landscape, harvest small pieces and follow a recipe for blending and growing them.
It is simple to propagate and grow with a little patience. When possible, use a supplier for larger quantities, like Moss Acres in Pennsylvania. They insure proper harvesting and regeneration on their 12-acre farm. We want to mimic natural ecosystems, not wipe them out.
The No. 1 secret to growing great moss? Study it. Walk in the woods. Find small streams to mimic. I often bring my camera along so I can more authentically copy the ecosystem where the moss is growing.
