Asclepias Plant Growing & Care Guide for Gardeners

Article by Dean Ravenscroft, Ph.D. - Updated 15th Nov 2023

In this Gardener's HQ guide, we'll explore cultivating Asclepias plants in your garden, indoor spaces, and other settings.

Milkweed, Pleurisy Root, & Butterfly weed: Cultivation & Garden Use

Plants from the Asclepias plant genus tend to be either half hardy or hardy perennials.

Some of the common names for members of Asclepias include Butterfly weed, Milkweed, Orange Milkweed, and Pleurisy root.

Milkweed plants normally flower in the summer.

Description of Milkweed and other Asclepias

Asclepias are often subshrub like in nature, and the they range in size from 30 cm to 2 metres (1 to 7 feet).

They are often grown in wildlife gardens as they are plants that are very attractive to butterflies (especially the monarch).

Asclepias tuberosa (Butterfly Milkweed).

Milkweed family members have clusters of blooms in red, orange, or other hot colour's.

Asclepias incarnata (Swamp Milkweed). Both photographs by Gmayfield10.

They make an ideal plant to grow when trying to plant a natural looking or butterfly garden.

Commonly Grown Asclepias Species Photographs and Plant Identification

Asclepias tuberosa

Asclepias tuberosa (Butterfly Weed), photograph by Frank Mayfield; CC.

Also see my How to grow Asclepias tuberosa guide.

Asclepias curassavica

Asclepias curassavica (Tropical Milkweed / Bloodflower / Cotton Bush), photograph by jimduggan24; CC.

Also see my Asclepias curassavica plant growing guide guide.

Asclepias syriaca

Asclepias syriaca (Common Milkweed / Butterfly Flower / Silkweed), picture by Peganum; CC.

Also see Asclepias syriaca growing guide.

How to Grow Asclepias

When planting Asclepias plants outdoors, it is best to sow out the seeds in either early spring or autumn. Once sown, lightly cover the seeds with soil.

If you plan to start the growing of milkweed and other Asclepias genus plants indoors, then you first should imbibe the seeds in the fridge for three weeks in soil, then sow them into peat pots.

Ideally you should do this 10 weeks before you plan to transplant them outdoors, normally in the late spring (or at the beginning of Autumn).

Germination of milkweed seeds normally takes about one to three months. Germination should be performed at a temperature between ten and twenty degrees Celsius (50 and 68°F).

Outdoors, the seedlings should be planted with a spacing of about 40 to 50 cm (16 to 20 inches). Locate in partly shaded to fully sunny parts of your garden. Asclepias plants prefer to grow in a sandy soil, but will grow in most non-heavy soils.

Caring for Milkweed and other Asclepias

Milkweed is very easy to look after, pinch back the heads when about 12 cm (5 inches) high. This will enable auxin hormones to make more heads (instead of having a single flower).

If you require more Asclepias plants, then you should (very) carefully take root cuttings in the spring.

Common Questions

How many members does the Asclepias genus have?

The Asclepias genus, known as milkweed, includes around 140 species. These plants are crucial for Monarch butterflies, which feed on them exclusively.

Do members of Asclepias make a good garden or landscaping plant?

Yes, Asclepias plants are excellent for gardens, particularly if you wish to attract and support Monarch butterflies. They produce clusters of vibrant flowers.

Which Asclepias species are most frequently grown by gardeners?

Asclepias tuberosa, or butterfly weed, and Asclepias syriaca, or common milkweed, are frequently grown for their attractive flowers and butterfly-hosting abilities.

Are members of the Asclepias plant genus fragrant?

Yes, many Asclepias species have fragrant flowers that also attract other pollinators, such as bees and hummingbirds.

What is the perfect location to grow Asclepias?

Asclepias thrives in full sun and well-drained soil. It's highly tolerant of poor soils and dry conditions, making it a great choice for difficult sites.

Is Asclepias invasive in the USA, if so in which states?

Asclepias is native to the USA and not typically considered invasive. However, some species can spread readily if conditions are right.

How do I remove Asclepias plants from my garden?

Asclepias can be removed by digging up the plants. Be aware that they have deep roots and may require some effort to completely eradicate.

Summary

The Asclepias genus, commonly known as milkweed, belongs to the Apocynaceae family. It includes around 140 species of perennial plants that are native to the Americas. Milkweeds are known for their clusters of small, intricate flowers and their role as a critical food source for monarch butterfly caterpillars.

Milkweed plants prefer full sun and well-drained soil. They can tolerate poor soil conditions and are quite drought-resistant, making them a good choice for xeriscaping. Some species can be aggressive spreaders and may require management to prevent them from taking over the garden. While these plants offer significant ecological benefits, their milky sap is toxic if ingested and can irritate skin.

I hope that you enjoyed this guide on Asclepias. You may also enjoy the following Gardener's HQ growing guides: How to grow Oxypetalum, Delphinium, Cyclamen plant, and Vinca minor plants.