Most gardeners have never given growing common milkweed a thought. After all, it is more of an invasive weed than anything, right!? Now, if you are a butterfly enthusiast, you would be thinking entirely different about this plant. It attracts butterflies. And importantly, perennial milkweed plants are essential for the survival of monarch butterflies. Once you know this, you just might find yourself planting and growing milkweed in naturalized settings and in your new butterfly garden. No butterfly garden is complete without this plant. And, you’ll be glad you planted it!
There are about 115 species. Common milkweed and butterfly weed are two of the more popular varieties. The plants are Native to three-quarters of Canada and the U.S. They are not native to the Pacific coast states and provinces. Wherever you find them, you will find butterflies. You might also spot a hummingbird unsuccessfully attempting to extract nectar from the flowers. Milkweed plants are essential to the endangered monarch butterfly. Monarchs only lay their eggs on the plants. Monarch larva and caterpillars eat milkweed plants exclusively. So, without this plant, monarch butterflies would go extinct.
These invasive plants can quickly populate a field or your butterfly garden. Their deeply growing rhizomes help them to spread rapidly. The silky seeds, like dandelion seeds, are scattered far and wide by the wind.
A Toxic Plant: Importantly, milkweed is poisonous to humans and animals.
Flowers Bloom: June to August
Flower Colors: These fragrant, globe-like flowers are greenish pink, mauve, pink, pinkish purple, rose, and white.
Plant height: 4 to 6 feet tall.
Plant Hardiness Zones: 3 – 9
Herbaceous Perennial, Asclepias syriaca
Despite being toxic, it does have some medicinal uses.
The sap is used for wart removal. And, it used to treat a variety of lung ailments.
Milkweed grows from seeds, the spread of their rhizomes, and plant cuttings.
Plant seeds early in the spring after all danger of frost has passed. Or, broadcast spread the seeds in fields or your butterfly garden in the fall. The plants are prolific reseeders. As previously mentioned, the seeds are carried long distances in the breeze. Like many other seeds, they must overwinter in the cold or go through seed stratification for at least 30 days.
In nature, the plants quickly fill in areas by the spread of their rhizomes. You can even dig rhizomes up to plant in another area.
Plant cuttings are another way to propagate them. And, the cuttings grow roots quickly. See: Cutting and rooting plants.
Final Plant Spacing: Space plants 18 – 24 inches apart.
Growing perennial milkweed in your butterfly garden or as a wildflower is easy. The plant is adaptable and not demanding.
They grow best in full sun. They thrive in just about any type of well-draining soil.
Milkweed plants are drought tolerant. Water them only during extended droughts. After watering, allow the top of the soil to dry out before watering again.
The plants do not need fertilizer to grow and thrive.
Also as an invasive plant, they tolerate crowding by other weeds and plants.
Ideal Soil pH: 5.5 – 7.5.
Plant Problems – Identify the causes and find the cures.
While the plant is toxic to many insects, there are over 450 known insects that feed on the plant! The most harmful of them are milkweed bugs, aphids, scale insects, spider mites, thrips, and whiteflies.
Very Important: Do not use insecticides on the plant. While insecticides will kill many harmful insects, it will also kill butterflies, including the endangered monarch butterfly.
Disease problems are not too common. Potential plant diseases include fungus problems, root rot in wet soils, and verticillium wilt.