The Asclepias tuberosa is native to North America and belongs to the dogbane family (Apocynaceae). The family Aclepiadaceae is considered a subfamily of Apocynaceae. Asclepias tuberosa is a species of milkweed. It is called butterfly weed because it attracts a lot of butterflies with its colour and copious production of nectar. Not only butterflies but also bumblebees, bees and other insects are attracted by this wonderful perennial. Unlike many other milkweeds the Asclepias tuberosa has no milky sapped stems. That it is why it is more often called butterfly weed instead of butterfly milkweed.
Every winter the stems and leaves die. Because the new growth emerges late in spring (end of April) you can combine it well with early flowering bulbs like for example tulips or daffodils. By the time the bulbs have withered the Asclepias tuberosa arises. That way there will not be an empty spot after the leaves of the bulbs have died. Slugs and snails enjoy the newly growing stems. After the stems have reached a height of about 8 inches (20 centimetres) they leave them alone in my garden.
The butterfly weed has hairy stems that usually stay upright without support. This perennial blooms for a long time and produces clusters of long lasting bright orange flowers. You can use it as cut flowers or in dried floral arrangements.
The flowers give way to spindle shaped seed pods. One year more seed pods are formed than the other year even though the flowers were visited by many insects. The seed pods split open when they are ripe releasing numerous silky-tailed seeds for dispersal by the wind. Most of the seeds drop to the ground near the original plants in my garden.
The Asclepias tuberosa is easily propagated by seed. Most of the seeds that have dropped on the ground will start to grow. You do not have to do anything special for this. You can also plant the seeds in a new spot where you want to grow a new butterfly weed.
The average height of the butterfly weed is about 28 inches (70 centimetres). I have placed it in a warm dry and sheltered spot and it grows up to about 35 inches (90 centimetres) there.
The Asclepias tuberosa is tuberous rooted and grows in a clump that slowly spreads. Because it has a deep taproot it is nog easily transplanted. Because of the deep taproot the butterfly weed is quite drought tolerant.
I have often read that the butterfly weed is not very hardy and that you should cover it in the winter. I never do that and it has survived -20 ºC (-4 ºF).
Characteristic: newly emerging every year
Exposure: sun/part shade
Foliage colour: green
Flower colour: orange
Flowering time: May - July
Hardiness: -20 ºC/ -4 ºF
Height: 28 inches/ 70 cm