Flower profile

Showy milkweed

Asclepias speciosa

Showy milkweed (Asclepias speciosa) is a flowering plant in the Apocynaceae family, native in the lower 48 states, blooming mostly June–July across the U.S.

Native in the lower 48

Showy milkweed is a wildflower that USDA PLANTS lists as native in the lower 48 states. It's on our flower lists for 10 states, and across the U.S. it's most often seen in bloom in June–July.

22states where USDA records it

10Bloomipedia state lists include it

27,287U.S. sightings*

*iNaturalist research-grade observations, as of October 17, 2026.

On our lists for: Colorado, Idaho, Montana, Nebraska, Nevada, New Mexico, North Dakota, South Dakota, Utah, Wyoming

Quick look

Asclepias speciosa is a milky-sapped perennial plant in the dogbane family (Apocynaceae), known commonly as the showy milkweed and is found in the western half of North America.
From Wikipedia's article Asclepias speciosa, CC BY-SA 4.0.

It belongs to the Apocynaceae family. ^iNaturalist
USDA PLANTS describes it as an herb (forb) with a perennial life cycle. ^{USDA PLANTS}
USDA PLANTS lists it as native in the lower 48 states and records it in 22 states. ^{USDA PLANTS}
In Colorado, most iNaturalist sightings of it in flower come in June–July. ^iNaturalist
In Utah, most iNaturalist sightings of it in flower come in June–August. ^iNaturalist
USDA PLANTS lists its flower color as white. ^{USDA PLANTS}
USDA PLANTS gives its bloom period as early summer. ^{USDA PLANTS}
USDA PLANTS lists a mature height of about 6 ft. ^{USDA PLANTS}
iNaturalist has 9,858 research-grade sightings of it in Colorado, ranking #3 among the 160 flowers on our Colorado list. ^iNaturalist
iNaturalist has 3,506 research-grade sightings of it in Utah, ranking #2 among the 153 flowers on our Utah list. ^iNaturalist
iNaturalist has 2,214 research-grade sightings of it in Idaho, ranking #2 among the 143 flowers on our Idaho list. ^iNaturalist

When does it bloom?

Flowering records by month across the U.S. (iNaturalist research-grade observations marked “Flowering”) (4,329 records)

Bloom time in the 10 states whose Bloomipedia list includes it

State	Type	Peak bloom	Sightings*
Colorado	Native	June–July	9,858
Utah	Native	June–August	3,506
Idaho	Native	June–July	2,214
Montana	Native	June–July	1,054
Nevada	Native	June–July	875
Wyoming	Native	June–August	739
New Mexico	Native	June–July	660
South Dakota	Native	June–July	617
Nebraska	Native	June–July	415
North Dakota	Native	June–August	389

Conservation status

Federal (U.S. ESA): Not listed No U.S. Endangered Species Act listing in the USFWS ECOS database. ^{USFWS ECOS}
NatureServe global: G5 Secure worldwide. ^NatureServe
Colorado: No list Colorado has no state law listing endangered or threatened plants, so we show NatureServe's Colorado ranks instead. NatureServe: S5, secure in Colorado.
Utah: No list Utah has no state law listing endangered or threatened plants, so we show NatureServe's Utah ranks instead. NatureServe: SNR, not yet ranked in Utah.
Idaho: No list Idaho has no state law listing endangered or threatened plants, so we show NatureServe's Idaho ranks instead. NatureServe: SNR, not yet ranked in Idaho.
Montana: No list Montana has no state law listing endangered or threatened plants, so we show NatureServe's Montana ranks instead. NatureServe: S5, secure in Montana.
Nevada: Not listed Not on Nevada fully protected plants, critically endangered (NAC 527.010). NatureServe: S4, apparently secure in Nevada. ^{NAC 527.010}
Wyoming: No list Wyoming has no state law listing endangered or threatened plants, so we show NatureServe's Wyoming ranks instead. NatureServe: S5, secure in Wyoming.
New Mexico: Not listed Not on New Mexico state endangered plant species (19.21.2.9 NMAC). NatureServe: SNR, not yet ranked in New Mexico. ^{19.21.2.9 NMAC}
South Dakota: No list South Dakota's endangered and threatened list (ARSD 41:10:02) covers animals only, so we show NatureServe's South Dakota ranks for plants. NatureServe: SNR, not yet ranked in South Dakota.
Nebraska: Not listed Not on Nebraska threatened and endangered species (163 Neb. Admin. Code ch. 4, § 004). NatureServe: SNR, not yet ranked in Nebraska. ^{163 NAC 4-004}
North Dakota: No list North Dakota has no state law listing endangered or threatened plants, so we show NatureServe's North Dakota ranks instead. NatureServe: SNR, not yet ranked in North Dakota.
Rare elsewhere: No other U.S. state ranks it S1, S2, SH or SX.

Checked October 17, 2026. Rankings and lists can change, so follow the links for the latest.

Can you eat it?

For peopleToxic (slight, per USDA)

USDA PLANTS rates its toxicity as “slight.” (USDA's rating covers people and livestock and doesn't say which parts.) NC State Extension has no page for it. ^{USDA PLANTS}

For petsToxic to dogs, cats and horses

ASPCA's entry “Milkweed” (Asclepias species), which covers the whole genus, lists it as toxic to dogs, cats and horses. Signs include: Vomiting, profound depression, weakness, anorexia, and diarrhea are common; may be followed by seizures, difficulty breathing, rapid, weak pulse, dilated pupils, kidney or liver failure, coma… ^ASPCA

🌿 Never eat a wild plant unless you're certain of its ID; this isn't medical advice. Worried about a person? Call Poison Control at 1-800-222-1222. Worried about a pet? Call your vet.

Where does it grow?

USDA PLANTS records showy milkweed in 22 states.

AKMEVTNHWAIDMTNDMNILWIMINYRIMAORNVWYSDIAINOHPANJCTCAUTCONEMOKYWVVAMDDEAZNMKSARTNNCSCDCOKLAMSALGAHITXFL

recorded by USDA PLANTS on our state lists not recorded

See the full list of states

Arizona, California, Colorado, Idaho, Illinois, Iowa, Kansas, Michigan, Minnesota, Montana, Nebraska, Nevada, New Mexico, North Dakota, Oklahoma, Oregon, South Dakota, Texas, Utah, Washington, Wisconsin, Wyoming.

Colorado counties with USDA records: Adams, Alamosa, Archuleta, Bent, Boulder, Cheyenne, Conejos, Crowley, El Paso, Elbert, Fremont, Gilpin, Gunnison, Huerfano, Jefferson, Kiowa, Kit Carson, La Plata, Larimer, Las Animas, Lincoln, Logan, Mesa, Mineral, Moffat, Montezuma, Montrose, Otero, Phillips, Pitkin, Prowers, Pueblo, Rio Blanco, Routt, Sedgwick, Washington, Weld, Yuma.

Utah counties with USDA records: Beaver, Box Elder, Cache, Carbon, Daggett, Davis, Duchesne, Emery, Garfield, Grand, Iron, Juab, Kane, Millard, Morgan, Piute, Rich, Salt Lake, San Juan, Sanpete, Sevier, Summit, Tooele, Uintah, Utah, Wasatch, Washington, Wayne, Weber.

Idaho counties with USDA records: Ada, Adams, Bannock, Bear Lake, Bingham, Butte, Canyon, Cassia, Clearwater, Custer, Elmore, Franklin, Fremont, Gem, Gooding, Idaho, Jefferson, Kootenai, Latah, Lemhi, Madison, Nez Perce, Owyhee, Payette, Power, Twin Falls, Valley, Washington.

Growing conditions

USDA PLANTS gives Showy milkweed a high shade tolerance, low drought tolerance and medium moisture use. It is rated for soil pH 5.0 to 7.0 and winter lows down to -33 °F.

Shade tolerance: High
Drought tolerance: Low
Moisture use: Medium
Soil textures it is adapted to: coarse, medium, fine
Soil pH range: 5.0 to 7.0
Minimum temperature tolerated: -33 °F
Frost-free days needed (minimum): 90
Annual precipitation range: 16 to 30 inches
Minimum root depth: 18 inches
Salinity tolerance: None
Fertility requirement: Medium
Growth rate: Moderate
Lifespan: Long
Active growth period: Spring and Summer
Fruit or seed: Black · Summer to Summer
Can be propagated by: container, seed
Commercial availability: Routinely Available

From the USDA PLANTS characteristics data for ASSP. USDA ratings are general guidance for the species, not a guarantee for your garden.

Names, range and relatives

Native status by region (USDA PLANTS): Canada: Native; Lower 48 states: Native.

Other scientific names (synonyms in USDA PLANTS): Asclepias giffordii.

County records: USDA PLANTS lists it in 478 counties across 22 states; the most are in Kansas (55), Minnesota (49), Colorado (38).

Other Asclepias on Bloomipedia (16): Common milkweed, Butterfly milkweed, Swamp milkweed, Green antelopehorns, Antelopehorn milkweed, Narrowleaf milkweed, Green comet milkweed, Zizotes milkweed, Tropical milkweed, Redring milkweed.

More from the Apocynaceae family (28 on Bloomipedia; most observed first): Lesser periwinkle, Greater periwinkle, Spreading dogbane, Pearl milkweed, Madagascar periwinkle, Honey-vine climbing milkweed, Hartweg's climbing milkweed, Oleander.

More Colorado flowers

Great mullein

Verbascum thapsus

Introduced

🌼 Blooms in CO: July–October

Blue columbine

Aquilegia coerulea

★ CO state flowerNative

🌼 Blooms in CO: June–August

Fireweed

Chamaenerion angustifolium

Native

🌼 Blooms in CO: July–August

Sources

USDA, NRCS. PLANTS Database, profile ASSP.
iNaturalist, Asclepias speciosa: taxonomy, research-grade observation counts and “Flowering” annotations, retrieved October 17, 2026.
Wikipedia, Asclepias speciosa (lead quoted under CC BY-SA 4.0).
State rare and invasive plant lists (13):
Show all 13 state lists
USFWS, ECOS species database (ESA listing check), October 17, 2026.
NatureServe Explorer, Asclepias speciosa (global and state ranks).
Edibility and toxicity: USDA PLANTS; ASPCA.
Photo: Colin Croft via iNaturalist · CC BY 4.0 · resized.