I have Verbena, Lantana and tall Zinnias growing for the butterflies. There's also Swan Plant (our New Zealand milkweed, Gomphocarpus physocarpus) and the butterflies are also enjoying the flowers of our Yellow Daisy Bush (Euryops Pectinatus).
Our flowers must be like a little nectar oasis in the bush area we live in, as there are no other gardens with flowers in our area. In most years we see very few Monarchs, however this Summer is different.
Each day we're seeing three or four Monarchs wheeling around the garden. They sup nectar from the flowers and then twist and turn together, up in the air, like dancers.
The other fun part about watching the Monarchs is seeing them chase birds. Yes, birds.
If any bird chances along their flight path they immediately chase them, at speed, until the bird is out of the way. I've watched them chase Sparrows, Barbary Doves, Tuis.