You do not "need" to bless each item per se. It is never a bad idea, however, to cleanse any altar item prior to using it in a spell or ritual. Some of your altar items can be used to cleanse others. For instance, some individuals burn sage, cedar, or other dried plants in their cauldron or chalice, then hold an altar tool they plan to use over the smoke to cleanse it. My personal favorite plant for cleansing is rosemary. Other practitioners might place a mineral (or any other altar tool that would not get damaged if wet) into a bowl of water and leave it outside under a full or new moon overnight to cleanse it prior to using it in a spell. I hope this helps answer your question!