Butterfly Milkweed
Asclepias tuberosa · Butterfly WeedUSDA | Grow Zone
3-9Outdoors all year in zones 3 to 9. Anywhere colder, keep it as a houseplant. Protect it below 40°F.
- Light
- Full sun, 6-8 hours
- Water
- Deeply but infrequently
- Humidity
- Moderate, tolerates low
- Temperature
- 65-85°F (18-29°C)
- Difficulty
- Beginner
- Growth
- Moderate
- Mature size
- 2-3 ft tall, 1-2 ft wide
- Pets
- Non-toxic to pets
Asclepias tuberosa, commonly known as Butterfly Milkweed, is a vibrant perennial native to North America. Its bright orange flowers attract butterflies and other pollinators, making it a favorite among gardeners looking to support local wildlife.
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Ideal temperature
65-85°F is where it grows fastest. Below 40°F cold damage starts.
Spacing and harvest
- Mature size
- 2-3 ft tall, 1-2 ft wide
- Plant apart
- 12-24 in
- Frost
- Hardy: survives frost
Everything it needs
9 essentials at a glance
Watering
Asclepias tuberosa prefers well-drained soil and should be watered deeply but infrequently.
Water every 1-2 weeks during dry spells, allowing the soil to dry out between waterings. Signs of over-watering include yellowing leaves and root rot, while under-watering may cause wilting and leaf drop.
Light
This plant thrives in full sun, requiring at least 6-8 hours of direct sunlight daily.
Ideal placement includes sunny borders or meadows, as it can tolerate some light shade but will produce fewer flowers in those conditions.
Soil
Asclepias tuberosa prefers sandy or loamy soil with a pH range of 6.0 to 7.0.
It requires excellent drainage to prevent root rot, so a mix of potting soil with sand or perlite is recommended for container growth.
Humidity
This plant prefers moderate humidity levels but can tolerate lower humidity environments.
To increase humidity, mist the leaves occasionally or place a humidity tray nearby. Signs of humidity stress include browning leaf edges and stunted growth.
Temperature
Asclepias tuberosa thrives in temperatures between 65-85°F (18-29°C) and is hardy in USDA zones 3-9.
It can tolerate heat but may struggle in extreme cold, so provide protection in winter if grown in colder zones.
Fertilizing
Use a balanced fertilizer with an NPK ratio of 10-10-10, applying it every 4-6 weeks during the growing season.
Reduce fertilization in late summer. Signs of nutrient deficiency include stunted growth and yellowing leaves.
Pruning
Prune Asclepias tuberosa in late fall or early spring to remove dead stems and promote new growth.
Use sharp pruning shears for clean cuts. Deadheading spent flowers during the blooming season can encourage more blooms.
Repotting
Repot Asclepias tuberosa every 2-3 years or when it becomes root-bound, indicated by roots growing out of the drainage holes.
Choose a pot 1-2 inches larger in diameter. Gently remove the plant from its pot, loosen the roots, and place it in fresh soil.
Propagation
This plant can be propagated through seeds or division.
For seeds, collect them in the fall and sow them in spring after stratification for 30 days. For division, carefully separate established clumps in early spring or fall and replant immediately.
When it's unhappy
Yellow leaves
Why it happens
Over-watering or poor drainage.
How to fix it
Allow the soil to dry out and ensure proper drainage.
Wilting
Why it happens
Under-watering or extreme heat.
How to fix it
Water deeply and consistently, especially during hot weather.
Root rot
Why it happens
Excessive moisture in the soil.
How to fix it
Improve drainage and reduce watering frequency.
Pest infestations (aphids, spider mites)
Why it happens
High temperatures and low humidity can attract pests.
How to fix it
Use insecticidal soap or neem oil to treat infestations.
Stunted growth
Why it happens
Nutrient deficiency or poor soil quality.
How to fix it
Fertilize with a balanced fertilizer and amend the soil as needed.
Care through the year
Spring
In spring, prune back any dead stems and prepare the soil for planting. Fertilize with a balanced fertilizer to encourage growth.
Summer
During summer, ensure consistent watering, especially during dry spells. Deadhead spent flowers to promote further blooming.
Fall
In fall, allow the plant to go dormant naturally. Cut back dead stems and collect seeds for propagation if desired.
Winter
In winter, protect the plant from extreme cold in zones 3-4 by covering the base with mulch. Avoid excessive moisture to prevent rot.
Toxicity & Safety
Asclepias tuberosa is non-toxic to pets and humans, making it a safe choice for gardens. However, ingestion of large quantities may cause mild gastrointestinal upset.
Good to know
How often should I water my Butterfly Milkweed?
Water Asclepias tuberosa every 1-2 weeks, allowing the soil to dry out between waterings. Adjust frequency based on rainfall and temperature.
What type of soil is best for Butterfly Weed?
This plant thrives in sandy or loamy soil with excellent drainage and a pH of 6.0 to 7.0. A mix of potting soil and sand works well.
Can I grow Butterfly Milkweed in a container?
Yes, Asclepias tuberosa can be grown in containers. Ensure the pot has drainage holes and use a well-draining potting mix.
Why are my Butterfly Weed leaves turning yellow?
Yellow leaves may indicate over-watering or poor drainage. Allow the soil to dry out and check for root rot.
When is the best time to prune Butterfly Milkweed?
Prune in late fall or early spring to remove dead stems and promote new growth. Deadheading spent flowers can also encourage more blooms.
Is Butterfly Milkweed safe for pets?
Yes, Asclepias tuberosa is non-toxic to pets and humans, making it a safe addition to gardens.
How can I propagate Butterfly Weed?
You can propagate Asclepias tuberosa through seeds or division. For seeds, stratify them for 30 days before sowing in spring.
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