You can get Ice Flowers Seeds by using Ice Flowers (only click on it) that are located here, on north glacier in Svargrond (green marks):
"There will be 15 Ice Flowers which have a small chance (~20%) of giving Ice Flower Seeds when used. It takes over 2-4 hours for the ice flowers to regrow (counting from the last time they were harvested)" - However, from my counting it takes 8 hours to make them regrow
"After successfully harvesting 10 of them you will get the achievement Ice Harvester."
''When you use the ice flower seeds on any fully grown plant it will never need to be watered again. Also the first time you combine the ice seeds with a fully grown plant you will earn the Achievement Preservationist.''
Source: Tibia Fandom
How can you profit from it? You can simply put those seeds on market. Depending on prices on your world, you could get up to 40k for each seed.
Eventually, you can use ice flower seed on fully grown plant and try to sell it on market, but it's not sure that there will be any buyers for it, in my opinion it would be better to sell just seeds.