Milkweed Plant Guide: How to Grow Milkweed in Your Garden

Milkweed plant (Asclepias syriaca) is an herbaceous perennial flower native to North America and part of the Apocynaceae and Asclepiadaceae families. It produces clusters of light purple flowers at the ends of light green, vertical stems. It spreads via rhizomes and seed pods that burst to spread its seeds. This common wildflower grows prodigiously on roadsides.

Milkweed is the only type of flower that acts as a host plant for monarch butterflies, because it provides a home for monarch eggs and a food source for the hatchlings. Milkweed is a perfect addition to a botanical garden or butterfly garden because it attracts all sorts of adult butterflies, hummingbirds, and other pollinators. Keep in mind that this flower is toxic to humans and some animals. It thrives in USDA Hardiness Zones three to nine.

There are over one hundred varieties of this popular, pollinator-attracting wildflower. Here are some of the most popular types of milkweed.

1. 1. Common milkweed (Asclepias syriaca): Common milkweed is an herbaceous perennial that grows about four feet tall. A. syriaca has light green, oblong leaves and blooms flower heads of tightly-bunched purple or light pink flowers. The flowers attract all sorts of pollinators, including the monarch butterfly. You can find it in many areas in the midwestern US, like Minnesota.
2. 2. Swamp milkweed (Asclepias incarnata): Swamp milkweed is an herbaceous perennial with cup-shaped flower heads. A. incarnata blooms flowers that range from pink, lavender, red, and white and thrives in USDA zones three to six found in the Midwest.
3. 3. Butterfly weed (Asclepias tuberosa): Butterfly weed—which also goes by the common names orange milkweed, butterfly milkweed, and yellow milkweed—has bright glossy green leaves. A. tuberosa blooms bright yellow and orange flowers filled with nectar and pollen.
4. 4. Tropical milkweed (Asclepias curassavica): Tropical milkweed in a native Central American and Mexican plant. It has long green leaves and bright yellow flowers. Tropical milkweed may contribute to the decline of the monarch butterfly population in the US, but there is debate around this topic.
5. 5. Whorled milkweed (Asclepias verticillata): Whorled milkweed is an herbaceous, drought-tolerant perennial with fine green stems and delicate white flowers that bloom from summer to fall.
6. 6. Showy milkweed (Asclepias speciosa): Showy milkweed is a native plant to Western states in the US such as California. It has purple and pink flowers that bloom in a spiky star shape.

The best species of milkweed for monarchs are common milkweed and swamp milkweed, Conservation groups such as Monarch Watch encourage growing milkweed across the monarch migration path in North America to support the waning population of these butterflies.

Follow these simple steps to grow your own native milkweed plants from seed in your garden.

• Stratify your seeds. Procure milkweed seeds from your local gardening center. Wrap them in a damp paper towel. Place the wrapped seeds in a sealed freezer bag or airtight container and leave them in the fridge for about thirty days.
• Prepare soil containers. Fill small containers or peat pots with seed starting potting mix. Water the soil so it is just moist enough, but not saturated.
• Sow your milkweed seeds. Press one or two seeds into each small container, about a quarter of an inch beneath the soil's surface. Leave the small containers in a warm sunny spot by a windowsill, or under grow lights. Leave the seeds for around two weeks, after which you should see sproutings.
  
• Transfer your baby milkweed plants to your garden. You can transfer your milkweed seedlings into larger containers or directly into your garden once they sprout a few leaves. Prepare your planting spot with average, well-draining soil or potting mix, and plant your seedlings into a shallow hole in your soil.
• Give your plants some space. If you're planting more than one milkweed plant, spacing is important. Common milkweed, whorled milkweed, and butterfly weed should have at least eighteen inches of spacing. Swamp milkweed spreads wider, so plant these specimens at least thirty-six inches apart.

Follow these steps to care for your burgeoning milkweed plants.

• Ensure your plants get lots of light. All varieties of milkweed need full sun to thrive. Plant milkweed in a location that gets full sun for at least part of the day, preferably in the morning.
• Water occasionally. Hardy milkweed does not require heavy waterings. Water your plants deeply every so often, when the first two inches of soil completely dries out.
• Watch for pests. Milkweed plants can be susceptible to aphids, spider mites, scale, whiteflies, and milkweed bugs. Gently remove these pests from your plant, either by hand or by using a spray bottle of water.

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