Botanical Name: Calotropis gigantea
Common Name: Giant Milkweed, Crown Flower, Swallow Wort
Description: I’m going to start this description off by repeating what I always say about milkweeds: It’s ok to plant a mixture of native and introduced milkweed plants in our gardens for the Monarchs. Some native milkweeds are very easy to grow, looking right you, Asclepias tuberosa, while others are more demanding, looking right at you Asclepias incarnata and others, with the Tropical Milkweed, Asclepias curassavica, also being very easy to grow. If you grow the Tropical Milkweed, please remember to cut it back in mid-November so the migrating Monarchs don’t hang around too long. If the scientists conclusively prove that Tropical Milkweed is the cause behind the OE issue, then I will stop selling it. But at the moment, they have not done that. Also, I’ll have more native milkweeds for sale this Fall, including tuberosa, incarnata, texana (the native white Texas milkweed), and all the others I can find.
Ok, let’s talk about Giant Milkweed. This is an introduced perennial that the Monarchs use as a host plant and somewhat as a nectar plant. It is a large plant, fast growing to 6-8′ tall x 4′ wide. In tropical areas it’ll get a good 15′ tall x 8′ wide. Give it the sunniest spot in your garden, but make sure it’s in a well drained area cause it gets root rot pretty easy from wet soils. I consider this to be a very tender perennial in our Zone 8b, so you can either take cuttings off it at the end of the season or haul it into your greenhouse/home if it’s grown in a container. Find the warmest micro-climate in your garden and plant it there if you want it to come back in the spring. You can also collect the seeds from it and try to grow it that way. The lavender/white flowers are very cool looking, lightly scented, and bloom spring to fall. They make a great cut flower. The leaves grow 8-12″ long and are kinda thick and leathery.
This plant in a 1-gallon container is 1-2′ tall and wide, not including the container.
Fun Fact: Genus name comes from the Greek words kalos meaning beautiful and tropos meaning boat in reference to the flowers. Specific epithet means unusually tall or large.
Aphids love milkweed plants. Ok, well, that’s not a “fun” fact, but it is a fact. I do not treat my plants with chemicals to get rid of the aphids because so many of my plants are host and/or nectar plants for butterflies and moths and the chemicals could kill them. What I do instead is let the good bugs, aphids, lacewings, parasitic wasps, aphid wasps, praying mantis, damsel bugs, soldier beetles, predatory midges, spiders, ambush bugs, pirate bugs, big-eyed bugs, etc, come do their job and eat the aphids. So, yeah, you might find some aphids on the plants you buy from me, that’s just nature’s way of giving the good bugs something to eat. So, please, let them eat aphids!!
Hardiness Zones 8b – 11