For information on growing Milkweed for Monarch caterpillars (and also as a nectar source for the Monarch butterfly), please check the section on Milkweed.
Here’s a partial list of Nectar-rich Plants for Monarch butterflies (and other butterfly species too), with different bloom colors, plant heights, blooming periods, hardiness levels (annual vs perennial), growing habits and habitat needs (with some photos below):
Aster (several species)
Bee Balm (Monarda didyma)
Blazing Star (Liatris scariosa) – blooms from August
Boneset (Eupatorium perfoliatum) – low, moist areas
Butterfly Bush (Buddleia)
Buttonbush (Cephalanthus occidentalis)
Cosmos (annual) (Cosmos)
False Dragonhead (Physostegia virginiana)
Flat-top goldentop (Euthamia graminifolia)
Goldenrod (several species)
Heliotrope (Heliotropium arborescens)
Joe Pye Weed (looks like milkweed) (Eutrochium)
Purple Coneflower (Echinacea purpurea)
Purpletop Vervain (Verbena bonariensis)
Summersweet (Clethra alnifolia)
Yarrow (Achillea millefolium)
The first generation of adult Monarchs on Prince Edward Island arrives around mid-July. The last generation leaves the island starting at the end of August and into September, when goldenrods and asters are in bloom.
It is important to offer the butterflies a variety of nectar-rich flowers over that two-month period, in addition to the milkweed plants.
If you buy live plants make sure they were not sprayed with harmful pesticides.
When there’s a choice of single vs double flowers, choose the single ones as it will be easier for butterflies to reach the flower center for nectar.
Mud-puddling – although I haven’t seen this behavior in the Monarch butterfly, many butterfly species gather at mud puddles to drink and obtain salt minerals this way. Some will also drink from dung or even carrion for the same purpose.