Milkweed (Asclepias curassavica), also called scarlet milkweed and blood flower, is a member in the family Asclepiadaceae. The South American native prefers growing in the subtropical and tropical climates in the United States. It is an evergreen perennial well adapted to growing throughout U.S. Department of Agriculture Hardiness Zones 8b through 11. In frost-free areas milkweed acts as a perennial, with cooler climates treating it as an annual. Plants have an erect habit with clusters of orange and red flowers blooming spring throughout fall, attracting butterflies. Milkweed is a hardy and relatively maintenance-free plant given the right growing conditions.
Purchase healthy plants for use in your garden. Select plants with green foliage with no signs of yellowing, as this can be a sign of sickness. Check plants for any insect infestations and use pest-free plants; infected plants can transfer bugs and diseases to other plants in your garden.
Plant the milkweed in a location in your garden that receives full sun to partial sun throughout the day. Milkweed is tolerant to a wide range of light conditions but requires some light for proper growth and bloom production.
Grow the milkweed in a well-draining and fertile soil medium for best results. Milkweed can grow in a wide range of soils and conditions, tolerating dry to wet soils, but grows best in fertile soils that drain.
Water the milkweed plants regularly once per week for the best growth and flowering. Plants are quite tolerant to drought conditions once established but will look best given regular applications of water.
Fertilize milkweed plants once every week with a 20-20-20 water-soluble fertilizer. Spray the entire plant’s foliage and blooms with the fertilizer mixture. This assures the plant receives proper nutrients for growth and promotes more blooms.
Prune milkweed plants to make them branch out and form a bushier habit. Trim off 1/3 of the plant’s branches when pruning.
Treat any aphid infestations that cause sooty mold on the plant’s foliage by spraying the plant with water, using horticultural oil or by using a solution of mild dish soap mixed with water. Spray the entire plant's foliage. Aphids usually do not do long-term harm to milkweed plants.