2.5" Mammillaria plumosa "Feather Cactus"
This plant must have extra drainage as is attained with the addition of extra pumice, perlite or other coarse material. It is essential that the soil must not remain waterlogged, and it is preferable to water from beneath, so that water does not remain on the plant as this can cause problems with rot. Refrain from watering on cloudy, humid or cold winter days. Protect from frost.