In the 5 tags you get to choose, you can put any word or "wordstring" you like.

A wordstring is words trailed together with no spaces like "myhomegarden"

These tags will automatically exist as soon as you use them, but they may not populate unless you get other people to use them as well.

My best advice for "permaculture" would be to add that tag along with "gardening" to see if it catches on.

For "baking" I would add your tag with "cooking", it may already be in the long list.

Hope this helps!