Description & Overview

Red Milkweed is a fast-growing, wet soil-loving, Wisconsin native perennial with beautiful deep pink flowers that attract many insects. The Monarch Butterfly uses it as a host plant. Although it can tolerate moderate moisture and even heavy clay, Red Milkweed, also known as Swamp Milkweed, is normally found in marshes, swamps, and near ponds, lakes, and waterways. Pretty flowers, a fast growth rate, and a love of wet soil make Red Milkweed a gem for a wetland garden. May also be known as Swamp Milkweed.

Core Characteristics

Category: Perennial

Wisconsin Native: Yes

USDA Hardiness Zone: to zone 3

Mature Height: 3-5 feet

Mature Spread: 3 feet

Growth Rate: Fast

Growth Form: Perennial

Light Requirements: Full Sun to Partial Shade

Site Requirements: Moist

Flower: Dark Pink

Bloom Period: July-August

Foliage: Green, Lanceolate

Fall Color: Red

Urban Approved: No

Fruit Notes: 2 or More Pods, 4 inches long

Suggested Uses

Red Milkweed can be used to naturalize a wetland habitat and also makes a wonderful addition to a wetland garden or a rain garden.

Although this species prefers wet soil, once it is established it can adapt to soil with average moisture content.

Red Milkweed is a fast-growing, wet soil-loving, Wisconsin native perennial with beautiful deep pink flowers that attract many insects. The Monarch Bu…

Wildlife Value

Most notably a host to Monarch (Danaus plexippus) and Queen (Danaus gilippus) butterflies. A Monarch will lay a very small (about the size of a large grain of sand) egg on the underside of Milkweed leaves. A tiny caterpillar will feed exclusively on the leaves upon hatching until it is mature enough to form a chrysalis. Adults also feed on nectar from Milkweed (as well as other) flowers. Healthy host plant populations are essential to the continuation of Monarchs as their life cycle is dependent upon Milkweed.

There are several Milkweed beetle species that rely on Milkweed to complete their life cycle. They are all herbaceous and generally not considered a nuisance. Eggs are laid at or near the base, the larvae hatch and burrow beneath the ground to feed on the milkweed’s roots. The adult pupates and eats the leaves, buds, and flowers. If you observe them in your yard and only have one Milkweed, consider planting more to offset what these beetles feed on.

Interesting to note, anyone who has torn the leaf or stem has come in contact with the white sticky latex sap that runs through milkweed. Both Monarch caterpillars and Red Milkweed Beetles bite through the leaf veins near their feeding site to stop the flow of the latex. This allows them to feed on the leaves without ingesting too much latex, which if left to flow freely can stick to their mouthparts rendering them immobile and unable to feed.

Just like Monarchs, Milkweed beetles are also toxic due to the ingestion of the toxic substance in milkweed.

Maintenance Tips

Red Milkweed is a short-lived species. When planted in a good site it should last multiple seasons but do not be surprised if it only persists for 1-3 seasons. May need to be replanted after a few years, or yearly, depending on how long it lives. If planted in an optimal site, they will also self-perpetuate and maybe even spread by seed.

Red Milkweed may need to be watered if the soil is in danger of drying out, such as during the hottest part of summer or during a drought. If planted in wet soil Red Milkweed requires little, if any, maintenance.

Propagation is best done by seed as Red Milkweed has a long taproot.

Red Milkweed is a fast-growing, wet soil-loving, Wisconsin native perennial with beautiful deep pink flowers that attract many insects. The Monarch Bu…

Pests/Problems

Few issues will arise with Red Milkweed if planted in the right location. Aphids are commonly found on Milkweed. That said, it can continue thriving and flowering despite aphids. The aphids can be sprayed with soapy water or blasted with a hose. Only do this if the plant is showing signs of stress and be sure to identify any Monarch eggs or caterpillars before doing so as any treatment will cause harm to our friends.

The presence of some aphids can help to boost populations of beneficial insects in the environment as they are a food source for some predatory insects such as beetles and flies. Ladybugs are a widely known predator of aphids. Keeping aphids around can boost the amount of beneficial predatory insects by providing them with food. These predatory insects can then also target other pests in a garden. While there are situations in which treatment would be the best course of action, Milkweed is rather tolerant of aphids and should be left alone as long as there is no visible effect on the plant’s fitness.

Leaf Lore

Name: Genus, Asclepias, named for Greek God of medicine Aesculapius due to Milkweed’s historical use as a medicinal plant. The species name comes from the Latin word “carn” which refers to a light pink, flesh-color hue that the leaves and stem can take on later in the growing season.

Historical Uses: Every part of Milkweed is poisonous. Large quantities can induce vomiting as well as cause weakness and spasms. The insects that feed off of milkweed are also poisonous. That said this plant has a myriad of uses, medicinal, edible, and practical.

The stems flowers and leaves can all be eaten after being boiled. An infusion of the roots was used to pass parasitic worms as well as a plethora of other uses the sum of which justify it being named after the actual Greek god on medicine.

Bark fiber can be used as cordage. Seed fluff is water repellant and can be used as stuffing for pillows and has been used inside life jackets. Latex in the leaves can be turned into rubber. Has much potential.

Companion Plants

To naturalize an area, it would be good to pair Red Milkweed with other wetland plants that include:

Red Milkweed is a fast-growing, wet soil-loving, Wisconsin native perennial with beautiful deep pink flowers that attract many insects. The Monarch Bu…
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Written by Julia Feltes