8 Types of Milkweed in Arizona (AND One to Avoid!)

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

Common Milkweed in Arizona

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!

8 Types of Milkweed in Arizona:


#1. Desert Milkweed

  • Asclepias erosa

Growing Information:

  • USDA Hardiness Zone: 4-11
  • Life Cycle: Perennial
  • Approximate Mature Size: 1.5 to 4 feet
  • Bloom Time: May to July

 

As the name suggests, this species is commonly found in desert regions. Desert Milkweed often grows on dry slopes and washes. The stems are yellow to green and broader at the base.

 

Identifying this species can be difficult as there’s some variation in the leaves. They grow in pairs on the stem and may be completely smooth or densely covered in cream-colored hair. They’re generally dull grayish or pale to dark green. Desert Milkweed blooms from May to July, forming rounded umbels or clusters of about 20 small flowers atop the stems. The flowers are white, cream, or yellow.

Desert Milkweed is quite adaptable and can be grown from seed in many home gardens. It needs well-drained sandy soils in areas with low organic matter. It should be planted in full sun. Like other milkweeds, its large taproot gives it excellent drought tolerance.

 

This species is a host plant for the Monarch Butterfly, Queen Butterfly, Clio Tiger Moth, and Euchaetes Zella Moth. The blooms also attract a variety of pollinators, including native bees.

 


#2. Butterfly Weed

  • Asclepias tuberosa

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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 Arizona.

 

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.

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.

 


#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 Arizona. 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. Broadleaf Milkweed

  • Asclepias latifolia

Glance at a Broadleaf Milkweed from a distance, and you may think you’ve spotted a cabbage plant rather than a milkweed! Their large, rounded, thick, dark green leaves give the plant its name and distinctive appearance. But both the leaves and the stems contain the milky sap that helps identify any milkweed species.

Clusters of cream, pale green, or yellowish flowers form along the stem and are often almost hidden by the leaves. The flowers give way to pairs of erect, large, smooth seed pods. The seed pods mature from green to brown and split open to release flattened brown seeds, each attached to a silky pappus that the wind disperses.

Broadleaf Milkweed in Arizona grows along trails, railroad right-of-ways, roadsides, and in desert scrub, pinyon-juniper woodlands, disturbed areas, and overgrazed pastures. The plants’ large, thick leaves help them to thrive in full sun and dry soil.


#6. Horsetail Milkweed

  • Asclepias subverticillata

horsetail milkweed

This milkweed has a delicate, feathery appearance, with narrow leaves forming in whorls. You might spot Horsetail Milkweed blooming throughout the summer, between May and September. Look for clusters of little white, greenish, or purplish star-shaped flowers.

The flowers give way to slender, erect seed pods. The seed pods split open upon maturity and release brown seeds with silky pappuses that disperse on the wind. The Zuni people traditionally gathered these seed pods and spun the fibers of the pappuses to make clothing.

You can find Horsetail Milkweed in Arizona growing in sandy or rocky plains, mesas, desert slopes, and along roadsides. Like other milkweeds, the Horsetail Milkweed is an important larval host plant for several butterfly species.


#7. Rush Milkweed

  • Asclepias subulata

Also called Desert Milkweed.

rush milkweed

Rush Milkweed is a unique species that grows many stalks from a single root crown and appears naked for most of the growing season! Like many desert perennials, Rush Milkweed only grows leaves after rain.

Thankfully, Rush Milkweed doesn’t need leaves to obtain energy. This horsetail-looking perennial can photosynthesize using the greenish-white tissue that covers its stems.

Amazingly, these plants can produce flowers and seeds with or without rainfall. Small clusters of about ten distinctive creamy white or yellow flowers form atop the bare stems. The flowers’ corollas are folded back to expose five tiny column-like structures with little hooks at the top.


#8. Pineneedle Milkweed

  • Asclepias linaria
Asclepias linaria. (2023, September 19). In Wikipedia.

Pineneedle Milkweed is the largest milkweed species in Arizona, reaching a surprising 5 feet tall!

As you probably guessed, it’s named for its thin, soft pine-needle-like leaves. These narrowly linear leaves are alternately arranged up the entire stems. It forms small clusters of creamy white or greenish-white flowers at the tips of its stems.

Researchers have found that this particular milkweed species is especially helpful for the Monarch Butterfly. Its leaves contain high cardenolide levels, which helps the Monarch Butterfly fight off the OE parasite (Ophryocystis elektroscirrha).


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 Arizona 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 Arizona?

 

Check out this guide!

 


Do you have milkweed in your garden?

 

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

 

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