Several years ago I started seeing growers selling giant milkweed (Calotropis gigantea) at butterfly gardening festivals. These were large plants in 3 gallon pots that sold in the neighborhood of $25. Though I had not seen any with monarch caterpillars, I was assured the giant milkweek was a good host plant. After seeing them several times, I finally broke down, purchased one and started taking cuttings. My hope was to be able to offer smaller plants at a lower price. They are not the easiest thing to propagate, but I have several going and sell them in a 1 gallon pot for $9.99.
Giant milkweed gets to be a large plant several feet high and would be great in ground here in central Florida except that our winter weather is a bit too cold. Calotropis is recommended for US zones 10B-11. We are 9B. My recommendation is to grow it in a large container and bring indoors when the temperature dips into the 30s.
The leaves of giant milkweed are large and a silvery green. The flowers come in lavender or white, though I only have the lavender. I've had plenty of flowers, but have yet to get any seed pods.
So the big question for butterfly gardeners is are they good host plants? Answer:
I've had lots of healthy monarch caterpillars on my giant milkweeds. And, as you can see, the large leaves give them more to eat than regular milkweed and also make a nice platform for collecting caterpillar poop.