Milkweed Seeds - Swamp


Asclepias incarnata

Beautiful rose to lilac blooms on tall 35 - 50" plants set swamp milkweed apart. A good choice for the back of border plantings, or place it near streams or boggy areas, as this variety gets its name because it tolerates having wet feet. One of the best varieties for attracting Monarchs, but also just a great all around pollinator plant. Seeds must be cold stratified for best germination. Summer blooming. Full sun to part shade. Perennial. 
  • Planting Information
  • Growing Information
Seeds per Packet
Packet weight
Seeds per 1/8 oz
 Seeds / oz
900.5 gram 
Planting SeasonIdeal Soil TempSunFrost Tolerance
Fall65-80°FFull SunLightly Tolerant
Sowing MethodSeed DepthDirect Seed SpacingDays to Harvest
Direct Seed1/8"6-8"70
Mature SpacingDays to SproutProduction CycleSeed Viability
24-36"21-28Perennial2-3 years

Site Selection


These North American native milkweeds are hardy perennials that will tolerate full sun to partial shade and thrive in a wide variety of soils. Swamp milkweed (A. incarnata), as the name suggests, prefers moist soils, but will tolerate average soils if not too dry.




For best results, expose seeds to moist, cold conditions (stratification) prior to sowing. For cold stratification, place seeds in moist potting soil or sand and store in a refrigerator for 4-6 weeks. After stratification, sow seeds in containers or direct seed outdoors after the danger of frost has passed. Sow seeds 1/8-1/4" deep and 6-8" apart. Optimal soil temperature for germination is 65-80˚F. Seeds will sprout in 10-28 days. Thin seedlings so that mature plants are 24-36" apart.

Seeds can also be direct sown outdoors in winter where they will stratify naturally and germinate the in the spring.