PS I like the idea of a horse-themed garden too but that's another thread.

Years ago when coming up with "Harry Potter" plants for a fair garden I stumbled upon long lists of plants with Dragons & Monster type names or Witchcraft-y names. I ended up faking it in my display with normal plants that I assigned totally made up "true-to-the-story" scientific names. Gardeners got the joke.

I tried to do the Colors of Crayola once, using the box of 64 that I grew up with. It was fun but the rabbits messed me up after they got wind of the phlox I was using for white, red violet and magenta.

In one of her books Elizabeth Lawrence wrote that she had several friends who had witch's gardens. She described acquiring water hemlock in her garden and then mourning its loss -- although it does have a certain sinister grace it's very poisonous. Probably no more so than oleander or castor bean, but if you read descriptions of it you begin to feel that if you look at it you'll fall over dead.

Here's one for the horror garden genre: a standard dwarf bearded iris called Fingertips.

The iris Creative Stitchery has been said to have a birthday cake Fragrance. Got to get that one!