Grow Showy Milkweed from fresh Asclepias speciosa flower seeds. Showy Milkweed will produce beautiful clusters of pale pink flowers. The plants themselves grow to a mature height of about 24 to 40 inches tall. Showy Milkweed is known for attracting an array of beneficial insects such as bumblebees, lady bugs, hummingbirds and most importantly the endangered Monarch butterfly. Asclepias speciosa is grown as a perennial flowering plant that returns each year from it’s deeply established root system.