From monarchbutterflygarden.net, here are some milkweed plant ideas for attracting monarchs.
One of the best ways to see monarch butterflies is by enticing expectant mothers to lay eggs on your milkweed plants. There are over 100 species of milkweed in North America and these are some of the best ones for your butterfly garden. Try planting several varieties to increase your odds of seeing magnificent monarchs.
For most in the US and Canada, the best time to find monarch eggs on milkweed leaves is June through August, while adult butterflies can be seen from April through October.
Here are 30 varieties of this herbaceous perennial to consider for your butterfly garden: https://monarchbutterflygarden.net/milkweed-plant-seed-resources/