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How to establish a green roof using moss

To establish a green roof using moss on a relatively flat, shaded roof, the steps are incredibly simple:

1. Install your green roof waterproofing/membrane and drainage mat system as you normally would.
2. Apply 1½” of roofing soil medium (extensive or intensive mixtures are both fine).
3. Apply water retention gel powder – ½ lb per 100 square feet. Sprinkle evenly over roofing soil and then rake into the top ½” of soil profile.
4. Broadcast moss fragments at 65% to 100% surface coverage rate (higher coverage rate encourages more rapid growth and enhanced results). Moss Acres ships pre-shredded hypnum moss or rock cap moss to the site). IMPORTANT: Please note that for green roofs, plan on one case of pre-shredded moss to cover approximately 100 square feet, not the 150 – 200 square feet listed for terrestrial landscaping projects on the products page.
5. Set up a temporary irrigation system (preferably a mister system) and immediately water thoroughly until soil is saturated (typically 2-3 hours). For the first week, set timer for 10 minute, 18x per day watering cycles. For the next 90 days, set timer for 10 minute, 10x - 12x per day watering cycles. No additional watering should be required following this initial watering period for moss to survive. However, during dry periods regular watering will keep moss lush and green. DO NOT allow water to pond – this can kill moss – and do NOT over water. Moss likes damp conditions, not sloppy, wet conditions.
6. NOTE: A tacifying agent can also be used to help adhere moss to the roofing soil until the moss knits to the surface. The tacifying agent is to be broadcast onto the top of the soil medium prior to applying the moss. Please contact us to order this material.

Please call Nancy Church at 610-635-4144 to discuss in detail any green roof project for which you might be considering moss. Remember, the species of moss currently offered by Moss Acres thrive in shaded areas. Some partial sun can be tolerated, but lengthy periods of afternoon sun on a roof are not recommended. (Note: We are currently experimenting with sun-loving mosses for roofs, so feel free to inquire - nancy@mossacres.com for up to date information).

View green roof projects with moss here

Sample specification sheet

For help designing and specifying the underlying elements of a green roof, Moss Acres recommends Roofscapes, Inc. a green roof engineering, design and installation firm with expertise in civil engineering, roof gardening, roofing and waterproofing. Since its inception about a decade ago, Roofscapes, Inc. has been committed to developing performance-based specifications for green roofs designed to perform. Roofscapes selects and sources products that will best optimize the performance and aesthetic of the entire green roof system, and provides both design consulting or design/build services.

Contact Nancy Church at Moss Acres to discuss moss as a green roof plant, for help in selecting and specifying moss and other companion “ingredients” for starting a moss roof, and to find out about water-retention and tacifying agents that will help improve the early success of your moss roof. Remember, the species of moss currently offered by Moss Acres thrive in shaded areas. Some partial sun can be tolerated, but lengthy periods of afternoon sun on a roof are not recommended. (Note: We are currently experimenting with sun-loving mosses for roofs, so feel free to inquire for up-to-date information).

Pricing and Ordering information