How to Remove Moss From Concrete

Plant organisms such as moss grow on exterior concrete surfaces that are not exposed to sunlight and remain in a persistently moist state. These growths can be effectively removed using one of the following methods.

Instructions

Difficulty: Moderately Easy

Things You’ll Need:

• Protective gloves, goggles and mask for use with chemicals
• Garden sprayer or watering can
• Garden hose or power sprayer
• Water
• Stiff broom or scrub brush
• Ammonium sulfamate OR
• sodium pentachlorophenate OR
• formaldehyde in the form of formalin
• Copper nitrate OR
• Copper sulfate Or
• Baking Soda Or
• Lime
• Boiling water
• Concrete paint or clear concrete sealer

1. Ammonium sulfamate (see caution below!) is sold in garden supply stores under a variety of brand names such as Amcide, Amicide, Amidosulfate, Ammate, Ammate X-NI, Fyran 206k, Ikurin, Silvicide, and Sulfamate.). Follow manufacture’s guidelines for application. It is generally applied using a sprayer or watering can with a sprinkling spout, drenching all areas of concrete where moss is a problem. Avoid desirable flora including trees or shrubs. Choose a day or time when the air is still to circumvent damage to other plants. Be sure to read label carefully before use and follow all manufacturer's directions. Wash away any powdery residue with clear water.
2. As an alternative, a solution of 1 part sodium pentachlorophenate to eight parts water may be used. Thoroughly saturate areas where moss growth is present. Reapply if rain occurs within 24 hours. All plant growth should be eliminated in about one week. Remove dead plant matter using a stiff broom or brush. This method should inhibit further plant growth for several weeks or more. CAUTION: Sodium pentachlorophenate is a known carcinogen and should be used with care. Read warning below.
3. Regular household bleach is yet another solution for killing moss. However, brands of bleach specifically for killing mosses can be found in most garden centers. The normal mixture is ½ part water to ½ part bleach concentrate. Spray covering the area and leave on for 30 seconds then brush and hose off. Again, damage to clothing, other plants and grass is possible so follow directions on bottle carefully. The use of this method may keep moss from regrowing for up to one year.
4. Formaldehyde in the form of formalin mixed 1 part formalin to 49 parts water is another alternative. Copper nitrate or copper sulfate mixed 5 oz to 1 gal of water should also do the trick. Be sure to follow all manufacturers’ directions including cautions and warnings
5. Lime or baking soda sprinkled on affected areas will also kill moss. Let set 24 hours, then carefully sweep up, and dispose of powder
6. The most environmentally friendly application would be boiling water, which I would personally recommend over any chemical solutions. Carefully pour the boiling water over the area affected. Scrub with stiff brush or broom and wash away debris with hose.
7. If available, a power sprayer may also be used after any of these processes.

Tips & Warnings

• To help save the environment please start with simply boiling water to kill moss. Only try other suggestions if this is not a working solution.
• CARCINOGENS-chemicals which are capable of inducing cancer in humans or animals after prolonged or excessive exposure.
• CAUTION! AMMONIUM SULFAMATE MAY CAUSE IRRITATION TO SKIN, EYES, AND RESPIRATORY TRACT. MAY BE HARMFUL IF SWALLOWED OR INHALED.
• Always read all manufacturer's directions and cautions before using any chemical compounds!
• Remember to use your safty gear!