Tropical milkweed is a common garden addition because it is easy to grow, drought and heat tolerant, and food for monarch and queen caterpillars. Unlike other milkweed varieties, tropical milkweed does not need to be vernalized (cold-treated).
Start your seeds indoors 6-8 weeks before the last frost date for your area. Tropical milkweed can be grown in containers or the garden, and if you’re growing them in containers, they can be moved inside in the fall. Be sure that there are no aphids on the plant before moving it in (1 aphid can become many with no predators) - just use an insecticidal soap spray (or even water and a paper towel) and beware of any caterpillars, or if your plant is already inside, try to find some lady bug larvae to clean it up. You should always cut your milkweed back in the fall/winter to prevent disease in monarch caterpillars.
If growing in the garden, pick an area with partial shade or full sun. Milkweed grown outdoors should die back each winter and come up again from the roots unless the roots freeze. After cutting back to the ground in late fall/early winter, add mulch to protect the roots. Tropical milkweed can grow to 4-5’ tall each year. Flowers are attractive to bees and butterflies, and aphids will attract predators like the milkweed assassin bug, ladybugs, and syrphid flies.
To harvest seeds, you will see a green pod offshoot from the main plant. Wait until the pod starts to split, then snip off with scissors. Harvest before the pod fully opens or it will be harder to harvest the seeds. The seeds have a downy parachute (like dandelions) that should be removed. The seeds can be stored for later in a dry environment.
The only pests that really affect tropical milkweed are milkweed bugs. These orange and black bugs feed on milkweed seed pods and will make your seeds (if they form) sterile. Kill them when they are young by knocking them into a bucket of soapy water. Once they are older, milkweed bugs can fly away.