While the name “weed” in any plant name scares many gardeners, milkweed plants add beauty to the garden and are essential for providing habitat for monarch butterflies. Monarch butterflies will only lay their eggs on the leaves of milkweed plants, and then the larvae feed only on these leaves. These larvae then go through metamorphosis to transform into an adult Monarch butterfly.
Milkweeds of any kind make a great addition to the garden, and there is a species for just about any type of growing condition that you may have.
Asclepias tuberosa, Butterfly Weed, grows easily in average, dry to medium, well-drained soils and is my favorite milkweed for the landscape. It was actually named the 2017 Perennial of the Year by the Perennial Plant Association!
Butterfly weed prefers full sun and is also drought tolerant, which makes it really low maintenance. It grows 1 to 2.5 feet tall and will spread about 1 to 1.5 feet. It has clusters of bright orange or yellow-orange flowers from June to August. The attractive flowers of butterfly weed attract many species of butterflies besides monarchs.
Asclepias incarnata, Swamp Milkweed, prefers to grow in medium to wet soils in full sun. This species of milkweed is native to swamps and wet meadows as its name suggests, and it works well in rain gardens. It grows 3 to 4 (sometimes 5) feet tall and will spread about 2 to 3 feet. Its clusters of flowers can be white, pink or mauve, and it also attracts many species of butterflies in addition to monarchs.
Others include the Common Milkweed (Asclepias syriaca) which tolerates moist, well drained soils to dry soils, Whorled Milkweed (Asclepias verticillata) which is white flowered and tolerates dry soils, or Balloon Plant (Asclepias physocarpa) which has unusual round seed pods, among others.
Milkweeds take a little manipulation to start from seed, but once they germinate, they thrive and frequently self-sow in the garden. Milkweed seeds need to go through a period of cold to germinate, which is called cold stratification. This process is a natural instinct of the seed to prevent it from germinating during winter when the seedling would not survive. Due to the need for cold stratification, there are two ways you can plant your milkweed seeds:
- Sow the seeds about a fourth inch deep directly into the soil in the fall so the seeds experience the natural cooling and warming of winter and spring. Make sure to label where you planted your milkweed so that you don’t pull it from your garden when it comes up in spring!
- If you want to start your seeds in the spring, you can cold stratify the seeds inside about a month before you want to plant the seeds. You can do this by mixing the seeds into moist planting media. Then place the mixture in a sealed and labeled plastic bag and place it in the fridge for about 30 days. Keep an eye on the seeds to make sure they do not germinate in the bag, and if they do, plant immediately. After the seeds have gone through the period of cold in the fridge, you can sow them into your garden about a fourth inch deep.
Milkweeds are a great flower to add to the garden, but they can get a bad rap for being slightly aggressive. To prevent milkweeds from self-sowing throughout the garden, simply collect the seed pods before they split open freeing their seeds. You can then collect the seeds to add them elsewhere in the garden or to pass along to friends to attract butterflies to their gardens.