Irish moss, also known as Scotch moss or sandwort, usually fills gaps in rock gardens, around trees or in other landscape areas where a low blanket of green can highlight the design. The moss also produces small white flowers during the growing season in spring and summer, creating a miniature flower garden on its own. If your climate does not allow for the moss to thrive outdoors, or if you want to get a jump-start on the growing season and have moss ready to transplant in the spring, you can plant the moss in indoor growing pots.
Fill a planting pot at least 8 inches in diameter three-quarters full of well-draining potting soil. Make sure your chosen pot has drainage holes to prevent water from sitting in the soil and damaging the moss's roots.
Plant an Irish moss seed on top of the soil two months before the final frost of the year. If you are using a larger pot for multiple seeds, plant the seeds at least 8 inches from one another to allow for spread and growth.
Cover the seed with 1 inch of light sand. Water the soil and sand thoroughly so it is completely moist but not soaking.
Store the planting pot in an area where it will receive at least six to eight hours of sunlight each day. You can also replicate this necessary light with grow lights, though you will need up to 14 hours of grow light to simulate a full day of sunlight.
Fertilize the Irish moss with a balanced, liquid fertilizer every two to three weeks during the growing season. Follow specific product instructions regarding dilution rate, since the rate will vary by product.
Water the Irish moss anytime the top 1 to 1 1/2 inches of soil becomes dry. The moss grows best in constantly moist but not soaking soil.