“What types of milkweed should I plant in my garden?”

Common Colorado Milkweed

This may seem like a crazy question if you’re just getting started with native gardening. Why would you want to plant a weed?!

 

But milkweed isn’t a weed at all. Instead, it’s a flowering plant that attracts butterflies (think Monarchs), native bees, and other pollinating insects, which is an excellent thing!

 

This article will give you information about common types of milkweed in your area and which ones will be best for your garden. And, keep reading to the end to learn about a kind of milkweed you want to avoid!

 

You will notice a USDA Hardiness Zone for each Milkweed plant in the article. This refers to areas of the US where plants do best, based on temperature. Here is a map showing the hardiness zones of Colorado:

Hardiness Zones in Colorado range from 3a to 7a.

 

6 Types of Milkweed in Colorado:

 


#1. Butterfly Weed

  • Asclepias tuberosa

Types of Milkweed that live in Colorado

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Growing Information:

  • USDA Hardiness Zone: 3-9
  • Life Cycle: Perennial
  • Approximate Mature Size: 2 to 3 feet
  • Bloom Time: May to September

 

Butterfly Weed is a showy member of the milkweed family. Sometimes called Orange Milkweed, this perennial wildflower features large flat-topped clusters of tiny flowers that grow 2 to 5 inches across. The blooms are brilliant orange or yellow.

 

Interestingly, its dark green leaves and stems don’t produce the same milky sap as other species of milkweed in Colorado.

 

Butterfly Weed is an excellent choice for gardens and or wildflower meadows. The beautiful flowers are fragrant and are ideal for cut flower arrangements. They also attract native bees, butterflies, and honeybees to your garden. Butterfly Weed is also a host plant for Monarch, Gray Hairstreak, and Queen butterfly caterpillars.

Kinds of Milkweed in Colorado

This native flower is a great low-maintenance choice for the home gardener. Butterfly Weed’s deep taproots mean you’ll never need to water it once it’s established. In addition, this plant is highly drought tolerant and thrives in full sun. Butterfly Weed also does fine without any fertilization but grows best in rocky or sandy soil.

 

Unlike Common Milkweed, this species doesn’t transplant well and should be started from seed.

 


#2. Green Comet Milkweed

  • Asclepias viridiflora

Colorado Milkweed species

Growing Information:

  • USDA Hardiness Zone: 3-10
  • Life Cycle: Perennial
  • Approximate Mature Size: 1.5 to 2 feet
  • Bloom Time: June to September

 

Green Comet Milkweed flower clusters form in the pocket created by the upper leaves. They’re made up of 20 to 80 small, pale green flowers. Interestingly, the yellowish-green leaves of this species vary in shape depending upon their habitat. Plants from moist sites tend to have rounder leaves, while plants from dry sites have long, narrow leaves.

 

In the wild, this species is often found on shaded roadsides, savannas, and prairies with moist to dry soil. In the garden, you can grow Green Comet Milkweed from seeds. It grows best in light to moderate shade but will tolerate full sun. Medium-dry to dry soil is best. Green Comet Milkweed doesn’t need rich soil and will tolerate sandy or rocky soil with low organic matter.

 

This species is a good choice for low-maintenance gardens as its long taproot allows it to tolerate drought well. Unlike many other milkweeds, this species is easy to prevent from spreading. It doesn’t form the large colonies typical to other milkweeds, so it’s an excellent option for smaller gardens!

 

The Green Comet Milkweed’s copious nectar and sweet fragrance attract many pollinators, including honeybees, native bees, and butterflies. It’s also a host plant for Monarch Butterflies, though it can be more challenging for monarchs to find because of its scarcity and preference for partial shade.

 


#3. Showy Milkweed

  • Asclepias speciosa

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Growing Information:

  • USDA Hardiness Zone: 3-8
  • Life Cycle: Perennial
  • Approximate Mature Size: 1.5 to 3 feet; occasionally up to 6 feet
  • Bloom Time: May to September

 

As the name suggests, Showy Milkweed features flashy pink and white umbels or clusters of small flowers. The flowers are fragrant, and individual flowers look a bit like crowns. In ideal conditions, Showy Milkweed may grow as tall as 6 feet!

As a garden plant, Showy Milkweed has the benefit of being a less aggressive spreader than most other milkweed varieties in Colorado. It can be grown easily from seed or the cuttings of an existing plant. It’s very drought tolerant and can be grown in a wide range of soils.

 

Like other milkweeds, Showy Milkweed attracts native insects and Monarch Butterflies to your yard or garden. Monarchs will visit the flowers for nectar and lay eggs on the plants, which are host plants for the Monarch caterpillars. It will also attract beautiful Queen and Viceroy butterflies to your property!

 


#4. Antelope Horns

  • Asclepias asperula

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Growing Information:

  • USDA Hardiness Zone: 5-9
  • Life Cycle: Perennial
  • Approximate Mature Size: 1 to 2 feet
  • Bloom Time: March to October

 

Antelope Horns, also known as spider flower, tends to sprawl toward the ground instead of standing upright. The stems of this milkweed are green-tinged with maroon and densely covered in tiny hairs.

 

This milkweed species gets its name from its relatively distinctive seed pods. The curved, upturned pods are thought to resemble antelope horns. When viewed from a distance, these plants resemble a field of antelope. The leaves are narrow, up to 8 inches long, and fold inward along the middle vein. Look for the whitish-green or purple flower clusters during its long blooming season.

Like other milkweeds, Antelope Horns’ flowers attract a variety of pollinators. Large native bee species regularly visit the blooms. The plants are also hosts for Monarch, Soldier, and Queen butterfly caterpillars.

 

This species is relatively easy to grow from seed. Antelope Horns need full sun to thrive and prefer sandy or rocky soil with little organic matter. It’s a great low-maintenance choice, and it thrives without any fertilization and little watering due to its large taproot.

 


#5. Swamp Milkweed

  • Asclepias incarnata

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Growing Information:

  • USDA Hardiness Zone: 3-6
  • Life Cycle: Perennial
  • Approximate Mature Size: 3 to 5 feet
  • Bloom Time: June to October

 

As the name suggests, this moisture-loving perennial is typically found growing wild on creek banks and ditches or in openings in swamps, bogs, marshes, and other wet areas. So if you’re looking for a plant for the wet spot in your yard, Swamp Milkweed is a perfect choice.

 

This species thrives in wet, mucky clay soils. It’s great for planting around ponds or streams on your property. This species requires full sun to thrive and spreads through both seeds and underground rhizomes.

 

Like other milkweeds in Colorado, the blooms are clusters of smaller flowers. The light pink, purple, or white flowers of Swamp Milkweed will attract various species of native bees and butterflies to your garden. It’s also a host plant for monarch butterfly caterpillars.

 


#6. Zizotes Milkweed

  • Asclepias oenotheroides

Growing Information:

  • USDA Hardiness Zone: 7-9
  • Life Cycle: Perennial
  • Approximate Mature Size: 1 to 1.5 feet
  • Bloom Time: March to September

 

This species is also known simply as Zizotes or “hierba de zizotes.” It’s the least hardy species of milkweed in Colorado and requires a warm climate to survive.

 

The greenish-white flowers of the Zizotes Milkweed are notable for their long, slender hoods, which extend up and over the central column making this species easy to identify in bloom. The individual flowers look like tiny champagne flutes!

 

This species can grow in the wild in prairies, fields, desert grasslands, pinyon-juniper woodlands, and ditches with sandy or rocky soil. At home gardens, Zizotes Milkweed can be grown from seed. However, this species does not tolerate shade and should be planted in full sun with dry, sandy soil.

 

This milkweed species is especially notable because it can survive periodic droughts and even occasional mowing. As a result, it’s an easy way to incorporate pollinator-friendly, native plants into your landscape. In addition, like other milkweeds, this species is an important host plant for the caterpillars of Monarchs.

 


Tropical Milkweed

  • Asclepias curassavica

Growing Information:

  • USDA Hardiness Zone: 8-11
  • Life Cycle: Perennial
  • Approximate Mature Size: 3 to 4 feet
  • Bloom Time: March to November in temperate climates, year-round in tropical climates.

 

This non-native milkweed plant has become popular in recent years because of its flowers’ bright red coloring and how easy it is to plant and maintain.

 

Unfortunately, Tropical Milkweed planted in Colorado may do more harm than good.

 

It carries a parasite of Monarch Butterflies called Ophryocystis elektroscirrha, or OE, which can cause defects in the wings of Monarchs. Since it doesn’t die back and can bloom late, the plant itself may also confuse Monarchs by signaling a breeding season when it’s time to migrate.

To ensure you’re planting milkweed that will help your local ecosystem and attract native pollinators, always choose a native species!

 

Marketers of Tropical Milkweed seeds will use the names Mexican Milkweed, Bloodflower, Mexican Butterfly Weed, Mexican Orange Milkweed, and Semi-Tropical Milkweed. Steer clear of all of these!

 


Are you looking for more information on milkweed in Colorado?

 

Check out this guide!

 


Do you have milkweed in your garden?

 

What’s your favorite thing about this plant? Leave a comment below!