Swamp Milkweed Seeds

Swamp milkweed is predictably found in wet, mucky areas of central and eastern North America. Asclepias incarnata has no shortage of descriptive common names, including: rose milkweed, rose milkflower, swamp silkweed and white Indian hemp. No matter the preferred name, it always makes a positive impact on the environment. One of the few plants that can excel growing in wet clay soil, swamp milkweed is an important native flower, acting as a host plant to numerous beneficial insects and pollinators. The traditional medicinal uses of swamp milkweed add to its cultural significance. 

While swamp milkweed isn’t fussy about soil quality, it does require it to be wet. Plant it in low-lying or shady spots. It grows well in direct sun as long as it is well watered. Swamp milkweed starts the growing season slowly, germinating later in the spring than most other plants. It quickly catches up though; — upright, herbaceous stalks can grow to be 150 cm tall and bloom gloriously in the summer. The rounded umbrella-shaped clusters of flowers showcase stunning shades of purples, pinks and white.

Swamp milkweed plays a crucial role in the life cycle of the endangered monarch butterfly. The sweet nectar feeds the butterfly while the plant itself serves as a nest to lay their eggs. Savvy and sophisticated gardeners know native plants improve their local environment. Plant swamp milkweed where other plants don’t thrive and enhance your landscape’s ecological diversity and resilience. 

 
- Latin Name: Asclepias incarnata
- Life Cycle: Perrenial
- Canada Hardiness Zone: 3-8
- Days to Maturity: 120
- Planting Depth: 3-4 mm
- Plant Spacing:  50-90 cm
- Growth Habit: 1-1.5 m tall

GROWING INSTRUCTIONS

Native to North America, the many varieties of milkweed are abundant in the wild and extremely popular in pollinator gardens. Milkweed is well known for attracting monarch butterflies, as it is the only plant that its larvae will feed on. It is crucial to grow and support milkweed to keep the monarch population stable, as they are a very important pollinator. 

Milkweed grows quickly and vertically, up to 120 cm, on narrow stalks with broad green leaves. Bunches of aromatic pink, purple and white flowers begin to appear in midsummer. 

Seeds can be sown directly outdoors in the fall or started indoors early in the spring. Because indoor starts don’t go through a natural stratification process through the winter, this period will have to be simulated. It takes about 30 days, so plan accordingly. Wrap seeds in damp paper towels and put them into sealable plastic bags and place into the refrigerator undisturbed for 30 days.  

Using small peat or coco pots, place one or two seeds in each and cover lightly with 5 mm of soil. Seeds can be bottom watered. Place pots in a tray and add about 1 cm of water. The pots will absorb the water, keeping the soil and seeds moist. Move the pots under grow lights or to a sunny window and expect sprouts in about two weeks. 

Harden seedlings off after the danger of frost has passed. The pots can be transplanted directly into the garden and will decompose without disturbing the roots. Give milkweed full sun and plenty of space to grow tall and produce large bunches of flowers. It is tolerant of poor, dry soils as long as it is well-drained. Watering is only needed during times of extreme drought. Milkweed will thrive in dry conditions and overwatering can lead to fungal diseases. It will do well in a variety of climates and temperatures and does not require any fertilizing. 

If you’re concerned about your local ecology and have access to open fields or plenty of space, try planting milkweed from seed. It’s native, low maintenance and will attract and help repopulate the beautiful monarch butterfly. 

QUICK FACTS

- For a long time, Native Americans used the young leaves, stems and buds as food. 

- The silk from the seed pods was once used for stuffing pillows.

- Attempts at commercializing milkweed were numerous and included use in the manufacturing of paper, fabric, fuel, rubber and some medicinal uses.

- Milkweed seeds will remain viable for 2 years if stored in a cool, dark place, ideally between 4 and 10⁰C. After that, the germination rate may start to go down.