Several new varieties of ornamental flowers have been produced through genetic engineering. For example, the "True Blue Chrysanthemum":
and the blue rose:
and the mauve rose:
Now that genetic engineering of new plant species is becoming cheaper, perhaps we will see whole gardens or small ornamental forests created with very exotic-looking plants. Some may look like plants from forgotten eons, when dinosaurs ruled; others may look like something from an alien world -- trees with purple leaves and tangerine barks; flowers with every color of the rainbow; some plants glow neon green, others frosty blue, in the night, like from the film Avatar.
Perhaps this will become an art form, with artists showing off their creations to guests. For a fee, you can live for a few days inside the creation in a guest house. Walk out into an alien landscape by day; marvel at the shining arrangement by night.
The best experiences will be had in gardens that tell a story, that are not merely a random collection of amusements. Thought will go into justifying why one tree looks tall and brooding, while another glows crimson beginning in the wee hours of evening. Each should be like a theme in a symphony, that varies season by season, before repeating the story again in the following year.