Why doesn’t Anna paint backgrounds?
Anna generally chooses not to paint backgrounds as she likes to study and focus exclusively on her subject in all its detail - this is also a long standing tradition in botanical art. However, if you wish to add in a background, there are tutorials demonstrating how you can do this by creating washes. See the Phalaenopsis Orchid, the Magnolia and the Tree and Sky Landscape tutorials.
If you'd like to paint backgrounds in a loose style, check out the Course on Backgrounds in Loose Watercolour.