Pint size pot. Native perennial. Swamp Milkweed, and any type of milkweed, is a must for a native garden! It is adorned with showy clusters of bright pink flowers from June to August. All milkweeds, including Swamp Milkweed, are the sole host for the beautiful and endangered Monarch butterfly, whose numbers have declined precipitously in the last 20 years. Easily grown in moist to wet soils in full sun, this milkweed will thrive in average garden soil, as well. 3 to 5 feet in height.