The term “fast moss” is a general descriptor for any moss variety that grows and spreads quickly. In horticulture and landscaping, these mosses are valued for their ability to rapidly establish a lush, green ground cover. Their accelerated development allows gardeners to achieve a soft, verdant aesthetic on soil or rocks without a long waiting period, making them a popular choice where speed and coverage are priorities.
Common Fast-Growing Moss Species
Sheet Moss (Hypnum curvifolium or Hypnum imponens) is a popular species known for rapid coverage. This is a pleurocarpous moss, meaning it grows in a creeping, carpet-like fashion. Its delicate, feathery fronds overlap to form dense, smooth mats that resemble a soft, green blanket. Sheet Moss thrives in shaded locations with consistently moist, acidic soil and is frequently used as a ground cover in shade gardens or as a base layer in terrariums.
Cushion Moss (Leucobryum glaucum) offers a distinct, mounding growth habit. As an acrocarpous moss, it grows upright in dense, compact clumps that resemble soft, green pillows. The foliage has a unique silvery or whitish-green hue, which can brighten shady garden spots. Cushion Moss prefers partial to full shade and acidic soil but is less tolerant of constantly waterlogged conditions, making it a good accent plant in rock gardens or at the base of trees.
Java Moss (Taxiphyllum barbieri) is a staple in freshwater aquariums. Native to Southeast Asia, this moss is adaptable and can thrive in a wide range of water and lighting conditions. It readily attaches to driftwood, rocks, and other decor, forming loose, flowing mats of green. Aquarists appreciate Java Moss for its rapid growth, ease of care, and its function as cover and a foraging surface for shrimp and small fish fry.
Methods to Accelerate Moss Growth
To encourage any moss to grow quickly, replicate its preferred natural environment. Most terrestrial mosses flourish in areas with consistent moisture, high humidity, and shade. They do not have true root systems, instead using rhizoids to anchor themselves, so they can grow on compacted, poor soil. Maintaining a slightly acidic soil pH, between 5.0 and 6.0, is also beneficial, and regular misting is more effective than deep watering as mosses absorb water directly through their leaves.
To propagate moss over a large or uneven surface, a “moss slurry” or “moss milkshake” is an effective technique. This method involves blending collected moss fragments with a liquid medium that provides a sticky, nutrient-rich base for them to adhere to a new surface. Breaking the moss into smaller pieces increases the number of points from which new growth can begin, speeding up the colonization process.
In a blender, combine approximately two parts clean moss with two parts water and one part a cultured dairy product like buttermilk or plain yogurt. The dairy product adds a slight acidity that mosses prefer and helps the mixture stick to surfaces. The concoction should be blended until it reaches a thick but spreadable consistency, similar to a milkshake.
Once the slurry is applied, the area must be kept consistently moist to allow the moss fragments to establish. This is best achieved by misting the area with water daily or as needed, ensuring it never completely dries out. With the right conditions of shade and moisture, new green growth can often be observed in a few weeks, developing into a full covering over a single growing season.
Controlling Rapid Moss Spread
While desirable in some settings, the same conditions that promote moss growth can lead to it becoming a nuisance in lawns or on pavers. The most sustainable approach to control is to alter these favorable conditions. Improving sunlight exposure by pruning overhanging tree branches and thinning shrubs can make an area less hospitable for moss. Addressing drainage by aerating compacted soil will also reduce the surface moisture it needs to thrive.
For existing moss, physical removal is often the first step. In lawns, vigorous raking or dethatching can pull up the moss mats. On hard surfaces like roofs or brick patios, a stiff brush or scraper can remove the growth. This method is most effective when the moss is dry and brittle, and while labor-intensive, it provides an immediate improvement.
When cultural and physical methods are insufficient, chemical controls can be used. Products containing iron sulfate are effective for controlling moss in lawns. When applied, the iron sulfate dehydrates the moss, causing it to turn black and die, after which it can be raked out. It is important to apply these products according to the label, as excessive concentrations can harm the surrounding grass. These treatments address existing moss but will not prevent its return if the underlying conditions are not corrected.