Swamp milkweed
Asclepias incarnata · Apocynaceae
The gardener's calendar
Ideal time to plant swamp milkweed: set it out when the soil is neither frozen nor waterlogged, and water generously as it establishes.
ID card
- Foliage
- Deciduous
- Flowering
- July to September
- Adult size
- 24 to 48 inches tall
- Growth
- Fast
- Hardiness
- -30 °C (zone 4)
- Origin
- North America
- Soil type
- Moist, well-drained, tolerates humidity
Care
Light
Red milkweed prefers full sun for generous blooming, but tolerates partial shade. A minimum of 4 to 5 hours of direct daily light ensures beautiful flowering. In very hot regions, a light afternoon shade can prevent water stress.
Watering
Water regularly to keep the soil moist, especially during growth and flowering. This species appreciates moisture and even tolerates wet areas or pond edges. Reduce watering in winter after dormancy.
Soil and Planting
Prefer rich, moist, well-drained soil. Red milkweed adapts to slightly acidic to neutral soils and can tolerate temporarily flooded areas. Adding organic matter at planting encourages establishment.
Fertilizer
A balanced fertilizer applied in spring at the start of vegetation is usually sufficient. Soils rich in organic matter reduce the need for extra fertilization. Avoid excess nitrogen, which would favor foliage over flowers.
Pruning and Maintenance
Remove spent flowers to extend blooming. In late autumn, cut stems back to ground level after the first frost. This plant regenerates vigorously in spring and doesn't require severe pruning.
Diseases and Pests
Red milkweed is generally robust and rarely troubled by pests. Watch for powdery mildew in case of excessive humidity and poor air circulation. Good air flow and watering at the base prevent most fungal problems.
Did you know?
Red milkweed is an essential host plant for the Monarch butterfly, whose caterpillars feed on it exclusively. By planting this species, you contribute to the lifecycle of this famous migratory butterfly. Native Americans also used this plant for medicinal purposes, which explains its common English name "swamp milkweed".
Where to buy it
Plant in spring or early autumn, avoiding spells of intense heat. Pick a plant with healthy foliage and roots that are not exposed. Best time: March, April, May, September.
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Tips generated and checked by Viridia — adapt them to your local climate.