Butterfly Milkweed (Tuberosa)

The Butterfly Milkweed (Tuberosa) is generally described as a perennial forb/herb. This is native to the U.S. (United States) has its most active growth period in the spring and summer . The Butterfly Milkweed (Tuberosa) has green foliage and inconspicuous orange flowers, with a moderate amount of conspicuous brown fruits or seeds. The greatest bloom is usually observed in the mid summer, with fruit and seed production starting in the summer and continuing until fall. Leaves are not retained year to year. The Butterfly Milkweed (Tuberosa) has a moderate life span relative to most other plant species and a slow growth rate. At maturity, the typical Butterfly Milkweed (Tuberosa) will reach up to 2 feet high, with a maximum height at 20 years of 0 inches.

The Butterfly Milkweed (Tuberosa) is easily found in nurseries, garden stores and other plant dealers and distributors. It can be propagated by container, seed. It has a slow ability to spread through seed production and the seedlings have low vigor. Note that cold stratification is not required for seed germination and the plant cannot survive exposure to temperatures below -33°F. has high tolerance to drought and restricted water conditions.

General Characteristics

General: Milkweed Family (Asclepiadaceae). Asclepias tuberosa is a perennial herb 3-9 dm tall with woody rootstocks. According to Kelly Kindscher (1992), Asclepias comes from the name of the Greek god of medicine, Asklepios. The species name, tuberosa, means full of swellings or knobs, referring to the enlarged root system. Butterfly milkweed stems are hairy, erect, and grow in numerous clumps. There is a watery sap within the stems and leaves. The leaves are alternate, simple, crowded, lance-shaped, 5-10 cm long, shiny green, smooth above and velvety beneath. The flowers are in showy, rounded to flat-topped groups near the ends of branches. Each flower has 5 petals, bent downward, orange to red or sometimes yellow, topped by a crown of 5 erect hoods, each one containing a short horn. Fruits are hairy, spindle-shaped pods 8-15 cm long. The numerous seeds each have a tuft of long white hairs at the tip.

Required Growing Conditions

Milkweeds grow in clumps beside roadways, on abandoned farmlands, and in other open areas throughout the United States. Butterfly milkweed grows on sandy, loamy, or rocky limestone soils of prairies, open woodlands, roadsides, and disturbed areas similar to other milkweed species. For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site.

Cultivation and Care

Butterfly milkweed is easily propagated by both seed and rhizome cuttings. Both seedlings and cuttings will usually bloom in their second year, although cuttings will occasionally bloom during their first year. Seeds and plants of selected cultivars are available from many nurseries. When the roots of the butterfly milkweed were more commonly harvested for their medicinal use, the plants were dug when dormant in the late fall. Butterfly milkweed increases by underground shoots and can be invasive. It is ideal in semi-dry places where it can spread without presenting problems for other ornamental species.

Seed Collections Asclepias tuberosa is easily propagated from seed. Collect seeds after the pods have ripened, but before they have split open. The seeds are wind dispersed, so be careful when gathering to place in a paper or burlap bag to avoid losing them. Butterfly milkweed seeds should be cold-treated for three months. Seeds can be directly sewn into the ground in the fall. The seed is very viable. It is not certain how long you can store the seeds.

Whole Plant Collections Propagation by cuttings of the tuberous rhizome is also easy and reliable. The cuttings should be made when the plant is dormant. Each piece of the rhizome should have at least one bud (they are about two inches apart). Timing of propagation is important. Harvest or divide plants and get the plants in the ground by late fall so they can develop enough root growth to survive the winter. Irrigation the first year will improve survival, and by the second year the root system should be well enough established so plants will survive on their own. Both seedlings and cuttings will usually bloom in their second year, although cuttings will occasionally bloom during their first year (Kindscher 1992).

General Upkeep and Control

Both milkweed and dogbane are burned in the fall to eliminate dead stalks and stimulate new growth. Burning causes new growth to have taller straighter stems (with longer fibers). It also stimulates flower and seed production.

When used for fiber, milkweed is collected in the autumn after the leaves have begun to fall off, the stalks turn gray or tan, and the plant dries up. If the milkweed stems will break off at the ground it's time to harvest. Breaking off as many stalks as possible encourages resprouting in the spring. The dried stalks are then split open and the fibers are twisted into string.

Vast quantities of fiber plants are required for nets, regalia, and cordage. Blackburn and Anderson (1993) quote Craig Bates of the Yosemite Museum that it takes approximately five stalks of milkweed or Indian hemp to manufacture one foot of cordage. A Sierra Miwok feather skirt or cape contained about 100 feet of cordage made from approximately 500 plant stalks, while a deer net 40 feet in length (Barrett and Gifford 1933:178) contained some 7,000 feet of cordage, which would have required the harvesting of a staggering 35,000 plant stalks.

Plant Basics
Growth Rate Slow
General Type Forb/herb
Growth Period Spring, Summer
Growth Duration Perennial
Lifespan Moderate
Plant Nativity Native to U.S.
Commercial Availability Routinely Available
Physical Characteristics
Bloom Period Mid Summer
Displays Fall Colors No
Shape/Growth Form Multiple Stem
Drought Tolerance High
Shade Tolerance Intolerant
Height When Mature 2
Vegetative Spread None
Flower Color Orange
Flower Conspicuousness Yes
Fruit/Seed Abundance Medium
Fruit/Seed Seasonality Summer Fall
Seed Spread Rate Slow
Gardening Characteristics
Propagations (Ways to Grow) Container, Seed
Moisture Requirements Low
Cold Stratification Required No
Minimum Temperature -33
Soil Depth for Roots 16
Toxic to Nearby Plants No
Toxic to Livestock No
After-Harvest Regrowth Rate Slow
After-Harvest Resprout Ability No
Responds to Coppicing No
Growth Requirements
pH Range 4.8–6.8 pH
Precipitation Range 28–28 inches/yr
Planting Density 3450–7200 indiv./acre
Soil Textures Coarse, Medium
Soil Depth for Roots 16
Minimum Frost-Free Days 135 day(s)
Salinity Tolerance None
CaCO3 Tolerance Medium
Sustainability & Use
Leaf Retention No
Palatability Low
Fire Resistant No
Causes Livestock Bloating None

Source: USDA, NRCS, PLANTS Database, plants.usda.gov.
National Plant Data Center, Baton Rouge, LA 70874-4490 USA