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Milkweed (Tropical)

Asclepias curassavica
Also known as: Butterfly Weed, Silkweed, Common Milkweed

Milkweed (Tropical) is a flower in the Apocynaceae family. It grows best in full sun to part shade with medium moisture, and is listed for USDA zones 8-11. Plants reach maturity about 100–120 days after planting and sit about 12 inches apart.

Varieties

1 from Seeds Now · sorted by days to maturity
  • Tropical (Silky Deep Red/Blood Flower)100–120 days

    Silky Deep Red Tropical Milkweed (Asclepias curassavica), also called Blood Flower, is striking in the garden and is a vital host plant for the endangered monarch butterfly. This easy care bushy perennial reseeds easily, isn’t fussy about soil or water, and can grow just about anywhere. Puts out bright, showy 2"-4" flower clusters in brilliant red-orange with yellow centers on slender stems that grow 2'-3' tall. Blooms continuously summer through fall, providing migrating monarchs with nectar snacks for their long journey and a place to lay their eggs. Can be grown as an annual in cooler grow zones. Lovely and long-lasting in cut flower arrangements. Life cycle: Herbaceous perennial Bloom season: Summer, fall Attracts: Beneficial insects, hummingbirds, bees, butterflies, and other pollinators Flower meaning: Dignity, freedom, rejection, remembrance, solitude As a medicinal plant, Milkweed has been used internally to treat diarrhea, gonorrhea, intestinal parasites and worms, pneumonia, spleen inflammation, and stomach tumors, and externally to treat bleeding, boils, corns, dermatitis, eye infections, ringworm, skin parasites, snakebites, sores, warts, and wounds. ⚠️ Although Milkweed is known to be safe when used correctly, all parts of the plant are toxic and may even cause death to people, pets, horses, and livestock if ingested in large quantities. The milky sap is a skin irritant. Do not ingest while pregnant or nursing. ⚠️ Medicinal properties are presented as information only, and are not a recommendation or prescription for use. Consult a medical professional before using any plant medicinally. NOTE: A parasite, Ophryocystis elektroscirrha (OE), travels with monarchs and is deposited on every plant they visit. In warm grow zones where this non-native milkweed does not die back from a killing frost, the OE parasite can build up and harm the caterpillars that feed on the leaves and the butterflies they become. A continuously blooming milkweed may also encourage the monarchs to dally rather than migrate, which interrupts their reproductive cycle. It’s easy to eliminate both dangers, by cutting your plants to the ground at least once per season.

    Growing notes: Botanical name: Asclepias curassavica|Hardiness zones: 8-11|Planting season: Spring, fall|Days to maturity: 100-120 days|Cold stratify: No|Depth to plant seeds: 1/4" deep - Soaking seeds in warm water overnight aids germination|Spacing between plants: 1'-2' apart|Days to germinate (sprout): 10-21 days|Germination soil temps: 60F-70F|Soil types: Clay, caliche, sandy, loamy, silty, rocky, chalky, rich, dry, moist, wet|Soil pH: 6.1-7.5|Water needs: Average|Sun needs: Full sun, part shade|Frost tolerant: No|Drought tolerant: Yes|Deer resistant: Yes|More facts about Milkweed:

    View on Seeds Now
Family
Apocynaceae
Category
Flower
Form
Stalk
Lifecycle
annual or perennial
Zone
8-11
Height
2.5–3.5 ft
Spread
1–2 ft
Sun
Full sun to part shade

Plant spacing

1 plant per square footSquare-foot planting diagram: one milkweed (tropical) fills a 1-foot square, spaced 12 inches from its neighbors.
1 plant per square foot

In a square-foot bed, space milkweed (tropical) about 12 in apart — that fits 1 plant in each 1-foot square (1×1). Wider rows or containers space the same.

Water
Medium

Plan your milkweed (tropical) planting

Add milkweed (tropical) to a free GardenDraft plan and get sow, transplant, and harvest dates computed for your ZIP code — with a drag-and-drop bed layout and reminders when it’s time to plant.

Start your free plan →

At a glance

Days to harvest
100–120 days
From transplant or sow to first harvest
Harvest style
Keep picking
Crops over several weeks
Frost tolerance
Hardy · to ~10°F
Lowest temperature the foliage usually survives

Growing timeline

When to plant and harvest milkweed (tropical)Planting timeline for milkweed (tropical), relative to last frost: start indoors from 10 weeks before last frost to 2 weeks before last frost; grow from 2 weeks before last frost to 12 weeks after last frost; harvest from 12 weeks after last frost to 15 weeks after last frost.Start indoorsGrowHarvestLast frostTransplant
Start milkweed (tropical) indoors ~8 weeks before transplanting 2 weeks before last frost; first harvest 12 weeks after last frost.
Seed to transplant
42-56 days
Outdoor planting
-14 to 0 days vs frost
Propagation
Seed
Schedule anchor
Last Frost

Care & troubleshooting— extension-sourced, with citations

When to feed, prune & water

Attract beneficial insects and protect pollinators

Protection
  • Routine carePlant insectary flowers and tolerate light pestsstrong evidence — extension confidence

    Grow a diversity of flowering plants (including small-flowered umbels and asters) to feed predators and parasitoids, and tolerate low pest numbers so natural enemies have prey to stick around.

    Source: UC IPM; UMN Extension

  • Routine careNever spray open bloomsstrong evidence — extension confidence

    Avoid insecticides on flowering plants and apply any needed sprays in the evening when pollinators aren't active, and favor selective products over broad-spectrum ones to spare bees and beneficials.

    Source: UC IPM

Support monarchs on milkweed

Care
  • Routine careTolerate aphids; never spraymoderate evidence — extension confidence

    Milkweed feeds monarch caterpillars and pollinators, so skip insecticides entirely. Oleander aphids look alarming but rarely harm the plant — knock them off with a water jet or wipe them off by hand and leave the rest for the butterflies.

    Source: Xerces Society; UMN Extension

Something looks wrong?

Describe what you see on your milkweed (tropical)and we'll rank the likely causes — most likely first, least-invasive fix first.

Aphids

Pestlow

Symptoms: clusters of tiny soft-bodied insects on new growth and undersides; sticky honeydew or sooty mold; curled distorted new leaves; ants tending them

  • CulturalBlast off with water· every 3 days · ~2 wksstrong evidence — extension confidence

    Knock colonies off with a strong jet of water in the morning; repeat every few days. Light infestations rarely need more.

    Source: UC IPM: Aphids

  • OrganicInsecticidal soap - label use only· every 1 wk · ~3 wksmoderate evidence — extension confidence

    For persistent colonies apply insecticidal soap to undersides per label. Avoid open flowers.

    Always follow the product label — it is the law.

    Source: UC IPM