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26 Irresistible Pima County, AZ Milkweeds (Asclepias spp.) to Grow for Butterflies

Table of Contents for Pima County, AZ Native or Nearly Native Milkweeds

General Information about Native Plant and Pollinator Gardens

When planting a native plant and pollinator garden in Pima County, AZ, you need to ensure that you have a selection of plants that provide blooms at different times of the year. In addition to the plants, you need to provide a source of water such as a birdbath or water feature, shelter for animals, and nesting locations for birds. Be sure to also include plants of different heights for perching. Resources you can use for more information on gardening in Pima County include the Arizona Native Plant Society and the Xerces Society, which has a list of pollinator plants for Arizona.

Location of Pima County, Arizona

State of Arizona map with Pima county highlighted in red.
Pima County in Red on a Arizona State Map — Own work., Public domain, via Wikimedia Commons

Pima County is located in southern Arizona. Tucson is the largest city in the county.

USDA Plant Hardiness Zones in Pima County, Arizona

2023 USDA plant hardiness zone of Arizona.
2023 USDA Plant Hardiness Zone Map for Arizona — USDA Public Domain

Pima County contains three plant hardiness zones and six subzones generally determined by elevation. Tucson is located in zone 9b, but the county ranges from 7a to 10a. When selecting plants in Tucson proper you will want to get those that can handle temperatures as cold as +250F. Other parts of the county will range from 00F to +300F depending on your hardiness zone.

Butterflies in Pima County, Arizona that are Hosted by Milkweeds (Asclepias spp.)

Monarch butterfly on green flower.
Green Flower with Monarch Butterfly (Danaus plexippus) — U.S. Fish and Wildlife Service, Public domain, via Wikimedia Commons
Queen Butterfly on Twig.
Queen Butterfly (Danaus gilippus) — Korall, CC BY 3.0, via Wikimedia Commons

Monarch Butterfly (Danaus plexippus)

The monarch butterfly is an iconic butterfly in North America and is a bell-weather of the environment. Having a distinctive orange color with black stripes, this butterfly has a wingspan of 3 in (7.6 cm) to 5 in (12.7 cm). The monarch butterfly uses milkweed to get cardenolides, a toxin that is distasteful to predators. This butterfly can have several flights a year and is known for its migrations to Mexico each year. However, some populations in California, Arizona, and Florida do not migrate and breed year-round (Urguhart, et al 1968).

Queen Butterfly (Danaus gilippus)

The queen butterfly is similar to the monarch butterfly, but is more of a solid orange in color and has brownish hued wing edges. When the wings are closed (the underside), it looks very similar and is hard to tell apart. However, it is smaller tha the monarch having a wingspan of 2.5 in (6.4 cm) to 4 in (10.2 cm). The similarity makes this butterfly a mimic of the monarch, but the queen also utilizes the milkweed for cardenolides. In the south, the queen can breed year-round, but in the north it breeds from April to November. This species, unlike the monarch, does not migrate.

List of Milkweeds that are Native or Nearly Native in the Pima County, AZ Area

1. White-stem Milkweed (Asclepias albicans), a Milkweed for Dry Soils

White-stem milkweed is one of the few shrubby milkweeds in North America and is perhaps the tallest. Due to its size, it can be used a screen plant, feed monarch and queen butterflies, and can handle the high heat conditions in Pima County. Once established this succulent plant requires little water, which makes it acceptable for desert conditions. This species resembles the desert milkweed (Asclepias erosa), but is larger.

Close-up of yellow flowers of white-stem milkweed (Asclepias albicans).
Flowers of White-stem Milkweed (Asclepias albicans) — NPS, Public domain, via Wikimedia Commons

Facts about White-stem Milkweed

  • Native to Arizona: Yes, south and southwestern counties (Kartesz 2015)
  • Native to Pima County: Yes
  • Natural Habitat: Dry areas such as deserts and gravelly sparsely vegetated places.
  • Height: 4 ft (1.2 m) to 12 ft (3.7 m), only shrubby and tallest milkweed in Arizona
  • Flower Color: greenish to white
  • Flowering Period: September to June
  • USDA Hardiness Zone: 9-11, hardy to +15F

Gardening with White-Stem Milkweed

2. Arizona Milkweed (Asclepias angustifolia), a Milkweed for Sandy and Rocky Soils

Arizona milkweed is native to Pima County and in your garden prefers some shading from the summer sun. Adapted to sandy and/or rocky soils, this plant requires a little more water than some other milkweeds and is hardy to +18F. If this species is planted, care needs to be taken as far as light requirements and water conditions.

Plant of Arizona milkweed (Asclepias angustifolia) with white flowers.
Flowers of Arizona Milkweed (Asclepias angustifolia) — Pamahon, CC BY-SA 4.0, via Wikimedia Commons

Facts about Arizona Milkweed

  • Native to Arizona: Yes, south and southeastern counties (Kartesz 2015)
  • Native to Pima County: Yes
  • Natural Habitat: dry woodlands, floodplains, prairies, meadows, and roadsides
  • Height: up to 3 ft (0.9 m)
  • Flower Color: pink or purple tinged white flowers
  • Flowering Period: June to July or year-round (Woodson 1954)
  • USDA Hardiness Zone: 7-10

Gardening with Arizona Milkweed

3. Spider Milkweed (Asclepias asperula), a Milkweed for Dry Soils

If you are able to keep your plants watered and need a fairly short milkweed, spider milkweed may be for you. The short stature of the plant may make this plant suitable for growing in a container. Other companion plants for spider milkweed include showy milkweed (Asclepias speciosa), butterfly weed (Asclepias tuberosa), and rush milkweed (Asclepias subulata). These plants in addition to a selection of nectar plants can turn your garden into a pollinator buffet.

Plant of spider milkweed (Asclepias asperula) with white flowers.
Spider Milkweed (Asclepias asperula) — Patrick Alexander from Las Cruces, NM, CC0, via Wikimedia Commons

Facts about Spider Milkweed

  • Native to Arizona: Yes, throughout (Kartesz 2015)
  • Native to Pima County: Yes
  • Natural Habitat: areas that are open, dry and rocky or sandy including pastures, desert shrub and swales
  • Height: 1 ft (0.3 m) to 3 ft (0.9 m)
  • Flower Color: Yellowish-green with a dark purple hood
  • Flowering Period: April to June
  • USDA Hardiness Zone: 5-9

Gardening with Spider Milkweed

4. Bract Milkweed (Asclepias brachystephana), a Milkweed for Moist Soils

Like the white-stem milkweed, this milkweed is a succulent that is well adapted to the desert. This species is often found from 3,500 ft. to 6,500 ft., but can exist in the valley of Tucson is attention is paid to drainage and organic matter in the planting. Other complimentary plants that will help attract more monarchs and have a variety of heights include white-stem milkweed (Asclepias albicans), Arizona milkweed (Asclepias angustifolia), spider milkweed (Asclepias asperula), showy milkweed (Asclepias speciosa), and butterfly weed (Asclepias tuberosa).

Red and white flowers of bract milkweed (Asclepias brachystephana) in a desert.
Flowers of Bract Milkweed (Asclepias brachystephana) — Patrick Alexander from Las Cruces, NM, CC0, via Wikimedia Commons

Facts about Bract Milkweed

  • Native to Arizona: Yes, southern counties (Kartesz 2015)
  • Native to Pima County: Yes
  • Natural Habitat: dry mesas and disturbed areas with sandy soil
  • Height: 0.5 ft (0.2 m) to 2 ft (0.6 m)
  • Flower Color: Red, pink, purple to greenish-purple
  • Flowering Period: April to September
  • USDA Hardiness Zone: 6-10

Gardening with Bract Milkweed

5. Pallid Milkweed (Asclepias cryptoceras), a Milkweed for Dry Sandy/Rocky Soils

Yellowish flowers of pallid milkweed (Asclepias cryptoceras) in a desert.
Pallid Milkweed (Asclepias cryptoceras) — Patrick Alexander from Las Cruces, NM, CC0, via Wikimedia Commons

Facts about Pallid Milkweed

  • Native to Arizona: Yes, rare in northern counties (Kartesz 2015)
  • Native to Pima County: No
  • Natural Habitat: sandy washes and canyon bottoms (Jepson eflora) and talus slopes (Baker 1971)
  • Height: 0.4 ft (0.1 m) to 1 ft (0.3 m)
  • Flower Color: Yellowish-green (Woodson 1954) to cream-white (Heil, et al 2013)
  • Flowering Period: April to June
  • USDA Hardiness Zone: 6-10

Gardening with Pallid Milkweed

6. Engelmann’s Milkweed (Asclepias engelmanniana), a Milkweed for Dry Soils

Engelmann’s milkweed is another milkweed well adapted to the sandy and rocky soil of the desert. This species does well with other milkweeds and nectar plants. The straight and reedy form of this plant can provide an interesting and worthy of conversation aspect to your garden.

Greenish-white flower cluster of engelmann's milkweed (Asclepias engelmanniana).
Flowers of Engelmann’s Milkweed — Asclepias engelmanniana Woodson observed in United States of America by calinsdad (licensed under CC0 1.0)

Facts about Engelmann’s Milkweed

  • Native to Arizona: Yes, throughout (Kartesz 2015)
  • Native to Pima County: Yes
  • Natural Habitat: dry prairies, canyons, and open woodlands having limestone or sandy soils
  • Height: 2 ft (0.6 m) to 5 ft (1.5 m)
  • Flower Color: cream to green
  • Flowering Period: May to September
  • USDA Hardiness Zone: 5-9

Gardening with Engelmann’s Milkweed

7. Desert Milkweed (Asclepias erosa), a Milkweed for Dry Sandy Soils

Desert milkweed is adapted to the desert conditions of Pima County, but it is not tolerant of being overwatered. Wherever it is planted, it needs to have good drainage and moderate watering. The plants are notable for having a silvery look when they first come out, but they become leathery with age. If you have a rocky or sandy area with good drainage this plant may be for you.

Close-up of white flowers of desert milkweed (Asclepias erosa).
Desert Milkweed (Asclepias erosa) — Joshua Tree National Park, Public domain, via Wikimedia Commons

Facts about Desert Milkweed

  • Native to Arizona: Yes, north-central and western counties (Kartesz 2015)
  • Native to Pima County: No
  • Natural Habitat: washes, roadsides, and sandy plains
  • Height: 1 ft (0.3 m) to 4 ft (1.2 m)
  • Flower Color: white, cream, green to yellow
  • Flowering Period: April to October
  • USDA Hardiness Zone: 4-10

Gardening with Desert Milkweed

8. Nodding Milkweed (Asclepias glaucescens), a Milkweed for Dry Soils

Cluster of pinkish flowers of nodding milkweed (Asclepias glaucescens).
Flowers of Nodding Milkweed (Asclepias glaucescens) — Edgar p miller, CC BY-SA 4.0, via Wikimedia Commons

Facts about Nodding Milkweed

  • Native to Arizona: Yes, central and southern counties (Kartesz 2015)
  • Native to Pima County: Yes
  • Natural Habitat: dry woodlands, rocky slopes, creek beds, and old fields
  • Height: 0.5 ft (0.2 m) to 4 ft (1.2 m)
  • Flower Color: white to greenish-white suffused with red or purple
  • Flowering Period: June to September
  • USDA Hardiness Zone: 7-11

Gardening with Nodding Milkweed

9. Hall’s Milkweed (Asclepias hallii), a Milkweed for Sandy, Well-drained Soils

Hall’s milkweed is a milkweed, that while not being native to Pima County, could potentially be grown in higher elevations. In other parts of Arizona this species grows from 6,000 ft to 8,000 ft. A possible companion plant might be dwarf milkweed (Asclepias involucrata). However, if grown in the Tucson valley it could have heat stress.

Red and white flowers of halls milkweed (Asclepias hallii).
Flowers of Hall’s Milkweed — Frankie Coburn, CC-BY-SA

Facts about Hall’s Milkweed

  • Native to Arizona: Yes, central and north-central counties (Kartesz 2015)
  • Native to Pima County: No
  • Natural Habitat: prairies, roadsides, rocky slopes, steepes, and woodlands
  • Height: 1 ft (0.3 m) to 3 ft (0.9 m)
  • Flower Color: white, whitish-green, rose, pink to purple
  • Flowering Period: June to August
  • USDA Hardiness Zone: 3-9

Gardening with Hall’s Milkweed

10. Swamp Milkweed (Asclepias incarnata), a Milkweed for Moist Soils

If you have land that is wet or moist in Pima County, this milkweed may be for you. Given its preference for moisture it would likely be best grown in the higher elevations of the county.

Pink flowers of swamp milkweed (Asclepias incarnata) from Pennsylvania.
Flowers of Swamp Milkweed (Asclepias incarnata) — Cbaile19, CC0, via Wikimedia Commons

Facts about Swamp Milkweed

Asclepias incarnata subsp. incarnata in Arizona

  • Native to Arizona: Yes, rare in one county in the south (Kartesz 2015)
  • Native to Pima County: No
  • Natural Habitat: shores of streams, lakes, ponds, and other wetlands
  • Height: 3 ft (0.9 m) to 5 ft (1.5 m)
  • Flower Color: pink or red
  • Flowering Period: July to September
  • USDA Hardiness Zone: 3-9

Gardening with Swamp Milkweed

11. Dwarf Milkweed (Asclepias involucrata), a Milkweed for Sandy Well-drained Soils

If you live at a high elevation in Pima County, this milkweed may be for you. Generally this species grows between 5,000 ft and 7,000 ft and is found in grassland habitats. A possible companion plant that grows in the same soils and elevations is Hall’s milkweed (Asclepias hallii). If planted in the valley of Tucson this species may experience heat stress and may become more of a factor with climate change warming.

Plant of dwarf milkweed (Asclepias involucrata) in a dry area.
Dwarf Milkweed — “Asclepias involucrata” by aspidoscelis is marked with CC0 1.0.

Facts about Dwarf Milkweed

  • Native to Arizona: Yes, eastern and southern counties (Kartesz 2015)
  • Native to Pima County: Yes
  • Natural Habitat: prairies and grasslands with sandy soil
  • Height: 0.5 ft (0.2 m) to 1 ft (0.3 m)
  • Flower Color: white to green (Singhurst and Hutchins 2015)
  • Flowering Period: May to June
  • USDA Hardiness Zone: 6-9

Gardening with Dwarf Milkweed

12. Lemmon’s Milkweed (Asclepias lemmonii), a Milkweed for Well-drained Soils

This milkweed is native and rare in Pima County and is tolerant of disturbance conditions and of fire. Wherever planted, this species likely needs soils that are neutral to slightly alkaline given its natural habitats. Some possible companion plants include zizotes milkweed (Asclepias oenotheroides), which also needs high pH soils and long-hood milkweed (Asclepias macrotis) that has a similar habitat.

Plant of lemmon's milkweed (Asclepias lemmonii) in a dry area.
Plant of Lemmon’s Milkweed — Asclepias lemmonii A.Gray observed in United States of America by ajlynde21 (licensed under CC0 1.0)

Facts about Lemmon’s Milkweed

  • Native to Arizona: Yes, rare in southern counties (Kartesz 2015)
  • Native to Pima County: Yes
  • Natural Habitat: rocky calcareous areas, oak/pine forests (Woodson 1954), open pine woods (Kearney and Peebles 1942), and roadsides (swbiodiversity.org).
  • Height: 1 ft (0.3 m) to 3 ft (0.9 m)
  • Flower Color: greenish-yellow (Woodson 1954) to purple (swbiodiversity.org)
  • Flowering Period: June to September
  • USDA Hardiness Zone: 9-10

Gardening with Lemmon’s Milkweed

13. Pineneedle Milkweed (Asclepias linaria), a Milkweed for Well-drained Soils

Pineneedle milkweed is native to Pima County and is a medium to tall plant. Generally the more water it gets, the taller it is. With this plant careful attention needs to be taken to make sure it has the right exposure, soils, and water.

White flower cluster of pineneedle milkweed (Asclepias linaria).
Pineneedle Milkweed — Asclepias linaria Cav. observed in Mexico by cornsnek (licensed under CC BY 4.0)

Facts about Pineneedle Milkweed

  • Native to Arizona: Yes, central and southern counties (Kartesz 2015)
  • Native to Pima County: Yes
  • Natural Habitat: open woodlands, rocky hills, sandy slopes (Woodson 1954), open ground (Meagher 1995), fields (Laferriere 1994), and limestone areas (Smith 1965)
  • Height: 1.5 ft (0.5 m) to 6 ft (1.8 m)
  • Flower Color: greenish-white (Woodson 1954) to white (Gentry 1942)
  • Flowering Period: April to November
  • USDA Hardiness Zone: 9-11

Gardening with Pineneedle Milkweed

14. Big-Seed Milkweed (Asclepias macrosperma), a Milkweed for Sandy Soils

If you have sandy soil and live at a higher elevation in Pima County, this may be a good milkweed for you. It is not native to the county, but could potentially live here. In the Tucson valley, this species may experience heat stress since its highest hardiness zone is that of Tucson.

White flowers of big-seed milkweed (Asclepias macrosperma).
Big-seed Milkweed — Asclepias macrosperma Eastw. observed in United States of America by Robb Hannawacker (licensed under CC0 1.0).

Facts about Big-seed Milkweed

  • Native to Arizona: Yes, central and northeastern counties (Kartesz 2015)
  • Native to Pima County: No
  • Natural Habitat: sandy soil of washes
  • Height: 1 in (2.5 cm) to 10 in (25.4 cm)
  • Flower Color: greenish purple tinged
  • Flowering Period: April to June
  • USDA Hardiness Zone: 6-9

Gardening with Big-seed Milkweed

15. Long-hood Milkweed (Asclepias macrotis), a Milkweed for Dry Soils

Long-hood milkweed, like Lemmon’s milkweed, is tolerant of disturbance and fire. It is native to the county and could potentially be planted in most areas and conditions.

Close-up of flowers of long-hood milkweed (Asclepias macrotis).
Flowers of Long-hood Milkweed — Asclepias macrotis Torr. observed in United States of America by Craig Martin (licensed under CC0 1.0)

Facts about Long-hood Milkweed

  • Native to Arizona: Yes, southern counties (Kartesz 2015)
  • Native to Pima County: Yes
  • Natural Habitat: dry hills and mesas (Woodson 1954), and limestone (Singhurst and Hutchins 2015)
  • Height: 0.3 ft (0.1 m) to 1 ft (0.3 m)
  • Flower Color: greenish-yellow to yellowish-white
  • Flowering Period: May to October
  • USDA Hardiness Zone: 8-10

Gardening with Long-hood Milkweed

16. Tufted Milkweed (Asclepias nummularia), a Milkweed for Dry Soils

Tufted milkweed can be used sparingly as a host for monarchs, since it has a high toxicity compated to other milkweeds. Generally this species grows from 4,000 ft to 5,500 ft and likely a good plant for those people who ive at high elevations in the county.

Plant of tufted milkweed (Asclepias nummularia) with pink flowers.
Tufted Milkweed in rocks — Asclepias nummularia Torr. observed in United States of America by henrya (licensed under CC0 1.0)

Facts about Tufted Milkweed

  • Native to Arizona: Yes, southern counties (Kartesz 2015)
  • Native to Pima County: Yes
  • Natural Habitat: dry grasslands, rocky places, and woodlands
  • Height: 1.5 in (3.8 cm) to 4 in (10.2 cm)
  • Flower Color: white, purple to rose
  • Flowering Period: March to August
  • USDA Hardiness Zone: 8-10

Gardening with Tufted Milkweed

17. Mojave Milkweed (Asclepias nyctaginifolia), a Milkweed for Dry Sandy Soils

Mojave milkweed may be a good choice if you live at a higher elevation in Pima County. This short milkweed is a grassland species that likes full sun, moderate water, and well-drained soil. Possible companion plants include slim-pod milkweed (Asclepias quiquedentata) and tufted milkweed (Asclepias nummularia). The short stature of this plant might make it candidate as a container plant given it has proper drainage.

Plants of mojave milkweed (Asclepias nyctaginifolia) in rocks.
Flowers of Mojave Milkweed — Asclepias nyctaginifolia A.Gray collected in United States of America by Utah State University (licensed under CC0 1.0)

Facts about Mojave Milkweed

  • Native to Arizona: Yes, throughout except for northeastern counties (Kartesz 2015)
  • Native to Pima County: Yes
  • Natural Habitat: washes, hillsides, roadsides, open woodlands, and grasslands
  • Height: 0.5 ft (0.2 m) to 1.75 feet (0.5 m)
  • Flower Color: greenish-white to greenish-yellow
  • Flowering Period: April to October
  • USDA Hardiness Zone: 7-9

Gardening with Mojave Milkweed

18. Zizotes Milkweed (Asclepias oenotheroides), a Milkweed for Medium to Well-drained high pH Soils

If you have a garden with neutral well-drained soil in a sheltered or higher elevation, this milkweed may suit you. It is small species and may be suitable as container plant or to fill those smaller places in the garden.

Close-up of greenish-white flowers of zizotes milkweed (Asclepias oenotheroides).
Flowers of Zizotes Milkweed (Asclepias oenotheroides) — Patrick Alexander from Las Cruces, NM, CC0, via Wikimedia Commons

Facts about Zizotes Milkweed

  • Native to Arizona: Yes, southern counties (Kartesz 2015)
  • Native to Pima County: Yes
  • Natural Habitat: rocky areas with limestone, fields, thickets, and roadsides
  • Height: 1 ft (0.3 m) to 2 ft (0.6 m)
  • Flower Color: white, greenish-white, yellow
  • Flowering Period: April to November
  • USDA Hardiness Zone: 7-9

Gardening with Zizotes Milkweed

19. Slim-Pod Milkweed (Asclepias quinquedentata), a Milkweed for Well-drained Soils

Herbarium specimen of slim-pod milkweed (Asclepias quinquedentata).
Herbarium Specimen — Asclepias quinquedentata A.Gray collected in United States of America by The New York Botanical Garden (licensed under CC BY 4.0)

Facts about Slim-pod Milkweed

  • Native to Arizona: Yes, rare in the northern and southern counties (Kartesz 2015)
  • Native to Pima County: Yes
  • Natural Habitat: rocky hills (Woodson 1954), oak woodlands (Van Devender, et al 2014), and fields (Laferriere 1994)
  • Height: 6 in (15.2 cm) to 12 in (30.5 cm)
  • Flower Color: greenish-purple (Woodson 1954) with a reddish to brown tinge (Fishbein, et al 2008) or red (Van Devender, et al 2014)
  • Flowering Period: June to August
  • USDA Hardiness Zone: 9-11

Gardening with Slim-pod Milkweed

20. Rusby’s Milkweed (Asclepias rusbyi), a Milkweed for Well-drained Soils

If you live at a higher elevation in a pinyon woodland, this milkweed may be a good choice. Due to this plant’s short stature, it would be a good container plant.

Greenish-yellow flowers of rusby's milkweed (Asclepias rusbyi) in an open area.
Flowers of Rusby’s Milkweed — Asclepias rusbyi (Vail) Woodson observed in United States of America by Robb Hannawacker (licensed under CC0 1.0)

Facts about Rusby’s Milkweed

  • Native to Arizona: Yes, central and northern counties (Kartesz 2015)
  • Native to Pima County: No
  • Natural Habitat: rocky hills, oak woodlands, and fields
  • Height: 0.5 ft (0.2 m) to 3.5 ft (1.1 m)
  • Flower Color: pale-green (Woodson 1954) to yellowish-green (Heil, et al 2013)
  • Flowering Period: May to July
  • USDA Hardiness Zone: 6-10

Gardening with Rusby’s Milkweed

21. Ruth’s Milkweed (Asclepias ruthiae), a Milkweed for high pH Well-drained Soils

Ruth’s milkweed is probably the smallest milkweed in Arizona. This plant is rare in the state and requires high pH soil and can handle the plant hardiness zone of Pima County. The small size makes it ideal as a container plant.

Plant of ruth's milkweed (Asclepias ruthiae) in a dry area.
Ruth’s Milkweed (Asclepias ruthiae) — Kenraiz, CC BY-SA 4.0, via Wikimedia Commons

Facts about Ruth’s Milkweed

  • Native to Arizona: Yes, rare in northern and northeastern counties (Kartesz 2015)
  • Native to Pima County: No
  • Natural Habitat: high pH clay and pinyon pine slopes
  • Height: 2 in (5.1 cm) to 4 in (10.2 cm)
  • Flower Color: purplish
  • Flowering Period: April to June
  • USDA Hardiness Zone: 6-10

Gardening with Ruth’s Milkweed

22. Showy Milkweed (Asclepias speciosa), a Milkweed for Medium to Well-drained Soils

Showy milkweed is a plant in butterfly gardens around the United States. In Pima County, this milkweed is at the upper limit of its hardiness zone. It is a small plant, making it suitable for containers, but whether planted or in a container, it needs good drainage.

Pinkish-white flowers of showy milkweed (Asclepias speciosa).
Flowers of Showy Milkweed — Asclepias speciosa Torr. observed in Canada by markeambard (licensed under CC0 1.0)

Facts about Showy Milkweed

  • Native to Arizona: Yes, throughout except western and southern counties (Kartesz 2015)
  • Native to Pima County: No
  • Natural Habitat: roadsides, fields and woodlands
  • Height: 1 ft (0.3 m) to 3 ft (0.9 m)
  • Flower Color: purple to pink
  • Flowering Period: April to June
  • USDA Hardiness Zone: 3-9

Gardening with Showy Milkweed

23. Rush Milkweed (Asclepias subulata), a Milkweed for Dry Soils

If you are looking for a milkweed that has an interesting growth habit and can handle the hot weather, rush milkweed could be for you. Other companion plants that compliment the look include showy milkweed (Asclepias speciosa) and butterfly weed (Asclepias tuberosa).

Plant of rush milkweed (Asclepias subulata) in an open area.
Plant of Rush Milkweed — Asclepias subulata Decne. observed in United States of America by Diana (licensed under CC BY 4.0)

Facts about Rush Milkweed

  • Native to Arizona: Yes, western and southern counties (Kartesz 2015)
  • Native to Pima County: Yes
  • Natural Habitat: washes and arroyos (Jepson eflora), benches of slopes (Roberts, et al 1998), desert areas (Shreve 1936), sandy flats (McLaughlin 1987), and roadsides (Felger 2014)
  • Height: 3 ft (0.9 m) to 6 ft (1.8 m)
  • Flower Color: yellowish-white to cream
  • Flowering Period: year-round
  • USDA Hardiness Zone: 9-11

Gardening with Rush Milkweed

24. Butterfly Weed (Asclepias tuberosa), a Milkweed for all Conditions

Butterfly weed is one of three milkweeds in the United States that has an orange coloered flower. In Pima County, this milkweed is at the upper limit of its hardiness zone and may experience heat stress in the future with climate change warming.

Orange flowers of butterfly weed (Asclepias tuberosa) in a garden.
Flowers of Butterfly Weed (Asclepias tuberosa) — Robert Coxe, Image

Facts about Butterfly Weed

  • Native to Arizona: Yes, throughout Arizona, except southwestern Counties (Kartesz 2015)
  • Native to Pima County: Yes
  • Natural Habitat: fields, roadsides and open woods
  • Height: 1 ft (0.3 m) to 3 ft (0.9 m)
  • Flower Color: orange
  • Flowering Period: June to October
  • USDA Hardiness Zone: 3-9

Gardening with Butterfly Weed

25. Whorled Milkweed (Asclepias verticillata), a Milkweed for Medium to Dry Soils

This milkweed is known for its bright green and dense foliage and is a small to medium size plant. While not native to Pima County, it can handle the plant hardiness zone, but may experience heat stress in the future. Smaller individuals may possibly be planted in containers.

Close-up of white flowers of whorled milkweed (Asclepias verticillata).
Flowers of Whorled Milkweed (Asclepias verticillata) — Joshua Mayer (wackybadger), CC BY-SA 2.0, via Wikimedia Commons

Facts about Whorled Milkweed

  • Native to Arizona: Yes, northwestern counties (Kartesz 2015)
  • Native to Pima County: No
  • Natural Habitat: meadows and fields
  • Height: 1 ft (0.3 m) to 3 ft (0.9 m)
  • Flower Color: green to white
  • Flowering Period: May to September
  • USDA Hardiness Zone: 3-9

Gardening with Whorled Milkweed

26. Green Comet Milkweed (Asclepias viridiflora), a Milkweed for Medium to Dry Soils

Green Comet milkweed is a small to medium sized milkweed that is rare in Arizona. While not native to Pima County, this plant can handle the plant hardiness zone, but may become heat stressed in the future.

Plant of green comet milkweed (Asclepias viridiflora).
Green Comet Milkweed (Asclepias viridiflora) — Matt Lavin from Bozeman, Montana, USA, CC BY-SA 2.0, via Wikimedia Commons

Facts about Green Comet Milkweed

  • Native to Arizona: Yes, rare in north-central counties (Kartesz 2015)
  • Native to Pima County: No
  • Natural Habitat: meadows and fields
  • Height: 1 ft (0.3 m)to 3 ft (0.9 m)
  • Flower Color: green when young, becoming yellow-green to purple-green with age
  • Flowering Period: July to August
  • USDA Hardiness Zone: 3-9

Gardening with Green Comet Milkweed

When selecting your Pima County, AZ milkweed, be sure to make sure that it grows in your zone and habitat.

Books where you can find out more about Monarchs and Butterfly Gardening in Pima County, AZ

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References for Pima County, AZ Milkweeds

  • Baker, William H. 1971. Noteworthy Records of Western Plants. Madrono 21: 199-200.
  • Felger, Richard Stephen, S. Rutman, and Jim Malusa. 2014. Ajo Peak to Tinajas Atlas: Flora of southwestern Arizona: Part 8, Eudicots: Acanthaceae-Apocynaceae. Phytoneuron 2014-85: 1-74.
  • Fishbein, Mark, Veronica Jaurez-Jaimes, and Leonardo O. Alvarado-Cardenas. 2008. Resurrection of Asclepias schaffneri (Apocynaceae, Asclepiadoideae), a Rare, Mexican Milkweed. Madrono 55: 69-75.
  • Gentry, Howard Scott. 1942. Rio Mayo Plants, A Study of the Flora and Vegetation of The Valley of the Rio Mayo, Sonora. Carnegie Institution of Washington Publication 527.
  • Heil, Kenneth D., Steve L. O’Kane, Linda Mary Reeves, and Arnold Clifford. 2013. Flora of the four corners region: vascular plants of the San Juan River drainage, Arizona, Colorado, New Mexico, and Utah. Monographs in Systematic Botany v. 124.
  • Kartesz, J.T. The Biota of North America Program (BONAP). 2015. Taxonomic Data Center. Link to website. Chapel Hill, N.C. [maps generated from Kartesz, J.T. 2015. Floristic Synthesis of North America, Version 1.0. Biota of North America Program (BONAP). (in press)]
  • Kearney, Thomas H. and Robert H. Peebles. 1942. The Flowering Plants and Ferns of Arizona. USDA Miscellaneous Publication 423.
  • Laferriere, Joseph A. 1994. Vegetation and Flora of the Mountain Pima village of Nabogame, Chihuahua, Mexico. Phytologia 77: 102-140.
  • McLaughlin, Steven P., Janice E. Bowers, and Kenneth R.F. Hall. 1987. Vascular Flora of Eastern Imperial County, California. Madrono 34: 359-378.
  • Meagher, Walter L. 1995. Flora of El Jardin Botanico, El Charco Del Igenio San Miguel De Allende, Guanojuanto, Mexico. Phytologia 78: 317-352.
  • Roberts, Fred M., Grant Fletcher, Steve Boyd, Andrew C. Sanders, Peter Lesica, Peter Husby, Stephen V. Cooper, and Job Kuijt. 1998. Noteworthy Collections Madrono 45: 326-330.
  • Shreve, Forrest. 1936. The Transition from Desert to Chaparral in Baja California. Madrono 3: 257-264.
  • Singhurst, Jason and Ben Hutchins. 2015. Identification of Milkweeds in Texas. Lady Bird Johnson Wildflower Center and Texas Parks and Wildlife.
  • Smith, C. Earle. 1965. Flora Tehuacan Valley. Fieldiana Botany v. 31 publication 987.
  • Urguhart, Fredrick Albert, Norah Roden Urguhart, and Francis Munger. 1968. Population of Danaus plexippus in Southern California. Journal of Research on the Lepidoptera 7(4): 169-181.
  • Van Devender, Thomas R., Guererro Reina, Lilia Ana, Aaron D. Flesch, Michael Jacobs. 2014. Additions to the Flora of Sonora, Mexico. Phytoneuron 2014-76: 1-8.
  • Woodson, Robert E. 1954. The North American Species of Asclepias L. Annals of the Missouri Botanical Garden 41: 1-211.
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Robert Coxe

Robert Coxe

Robert Coxe is a professional ecologist and botanist who has worked as the State Ecologist of Delaware and as an ecologist for the Western Pennsylvania Conservancy. He is also a former Past-President of the Pennsylvania Academy of Science. He currently is an innkeeper at McMullen House Bed & Breakfast LLC and a web designer and owner for Silphium Design LLC.

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