Tropical Milkweed
(Asclepias curassavica)


Plant Description:

Milkweed is a group of plants named for their milky sap, of which there are many species. Scarlet or Tropical Milkweed has bunches of orange, yellow, and red tubular flowers, and is one of two species most often grown in Florida gardens.  This species is an important nectar source for bees, butterflies, and other insects, and serves as a larval host plant for Monarch, Queen, and Soldier butterflies.  While typically root hardy in north Florida and perennial in south Florida, this plant can also be grown as an annual as it blooms during much of the year and reseeds freely.

Mature Size:     2-4 feet tall, 1-2 feet wide

Growth Rate:   Fast

Plant Habit:     Upright, unbranched stems

Plant Spacing:     18 to 24 inches


Ornamental Characteristics & Uses:

Foliage Color:     Green

Flower Color:     Red and yellow

Bloom Time:     Spring - Fall

Attracts Wildlife:     Butterflies, bees, and other insects

Uses:    Butterflies gardens; perennial beds, mass plantings


Growing Requirements: 

Cold Hardiness Zone(s):    8 - 11

Exposure:    Full Sun

Water Needs:    Low; high drought tolerance

Soil Tolerances:  Tolerates most soils

Soil pH:     Acidic to slightly alkaline

Maintenance:    Moderate


General Care & Growing Tips:

Clumps may form from overwintering crowns.  Stems should be cut back to the ground after flowering to stimulate new growth in spring.  Re-seeding is common but the species is minimally invasive.  Since milkweed serves as a larval host plant for butterflies, you can expect to see hungry caterpillars munching on the leaves, flowers and stems, occasionally striping plants clean.  Planting additional milkweed plants can sometimes help reduce noticeable damage by making sure there is plenty of food to go around.  However, after the larva are finished eating the milkweed they will pupate and emerge as new adult butterflies, and your milkweed plant will begin to regrow and recover quickly.


Common Pests:

Insects

Since the plant is used to attract beneficial insects, pesticides should not be used to manage pests.  Aphids can be a nuisance, but are easily managed using a strong spray of water from the garden hose.  If spider mites become a problem, infested plant material can be cut back and discarded.

The Milkweed Bug can also be found feeding on seeds and tissue of the milkweed plant.  These bugs resemble other harmful pest insects, but can actually be considered harmless since they tend to help keep the plant in check by reducing the number of seeds that go flying in the wind.

Like the Monarch butterfly, Milkweed bugs have few predators because they concentrate in their bodies bad tasting compounds found in the sap of milkweed plants.  Both insects use the bright black and orange coloration to advertise their bad taste.  Ingestion of these insects by animals can result in vomiting and even death, if enough are consumed.

During the one occasion that these Milkweed Bugs appeared in my north Florida garden, they did appear in large numbers.  If you feel that control is necessary, you can flick them off the plant into a jar of rubbing alcohol, or cut back the stems that are completely infested and drown them.

Pruning Tropical Milkweed to manage insect pests typically does not harm the plant as plants seem to respond positively to pruning and quickly regrow and recover from any damage.  In some cases, pruning can also result in a more heavily branched plant that produces more flowers.

Diseases

Leaf spot diseases are seen but not serious.  Rusts cause the formation of reddish colored spots.  Cucumber mosaic virus causes leaf mottling but no chemical control is available.


References:

Gilman, E.. (1999). Asclepias curassavica Butterflyweed, Milkweed, Silkweed.. University of Florida.  http://edis.ifas.ufl.edu/fp049

University of Arizona (1997). Milkweed Bug Informationhttp://insected.arizona.edu/milkinfo.htm

University of Florida (2012).  Gardening in a Minute: Milkweed http://gardeningsolutions.ifas.ufl.edu

University of Illinois. (n.d.). Large milkweed bug (Oncopeltus fasciatus)http://www.life.illinois.edu/ib/109/insect%20rearing/milkweedbug.html

Photo Credit: Alicia Lamborn

Fact Sheet written by Alicia Lamborn, Baker County Horticulture Agent, and Dr. Kyle Brown, Baker County Master Gardener.


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