Moss growing on the soil of your flower bed garden does not harm your plants, but indicates that your garden provides the perfect environment for moss. Moss will grow when the soil is in shade, very moist or is highly acidic, with a pH below 5.5. Eliminating one or more of these issues should get rid of the moss in your flower bed.
Apply an all-purpose contact herbicide, like glyphosate (Roundup), to a sponge. Wear rubber gloves when you use any contact herbicide. The herbicide can be absorbed into your skin, so protection is a must.
Brush your herbicide soaked sponge over the surface of the moss you wish to kill.
Wait about one week to 10 days. Usually, you will see that the moss has died. Dig or pull up the dead moss. Moss does not generally have much of a root system and is easily pulled, or rolled up, to remove it from the soil.
Correct the condition that caused the moss to grow in your flower bed. If your irrigation system is delivering too much water to the area, cut back. If your soil is retaining moisture too long, supplement the soil by working in compost and organic matter into the soil to open the soil up for better drainage.
You can also trim the lower foliage from your flowering plants to allow more light and air circulation to the soil. This will help in keeping new moss from establishing in your flower bed.