Commonly known as milkweed, the genus Asclepias has roughly 140 species of flowering plants.
While some see them as weeds, their beautiful and fragrant orange, pink, or purple blooms are undoubtedly a sight to behold.
Naturally, these flowers attract pollinators, most especially the monarch butterfly, making them a valuable addition to any butterfly garden.
When to plant milkweed? Milkweed seeds have to freeze and thaw to soften their coating and allow germination. That’s why it’s best to plant them in the fall. You can plant them in spring, but they will remain dormant until the soil warms up.
What Is Milkweed?
Back in the day, milkweed was used for its healing properties. Today, the seeds’ silky material is often used to fill lifejackets.
That said, they are mostly cultivated to house the larvae of monarch butterflies.
The plant’s bitter, milky juices serve as the larvae’s only food source, so without them, this iconic butterfly species will cease to exist.
More About Milkweed and Monarch Butterflies
Of all the plants in the world, Asclepias is the only genus that can host a monarch butterfly’s egg-laying.
Monarch caterpillars exclusively feed on milkweed leaves and won’t survive elsewhere.
Sadly, their natural habitat is widely affected by the widespread use of pesticides and the destruction of meadows for urban and agricultural development.
To help boost their population in your area, you can plant milkweed in your garden.
At the same time, this simple act will also increase the number of pollinators in your area.
As an irresistible pollinator, milkweed attracts different kinds of butterflies, bees, hummingbirds, and other beneficial insects.
Most Common Milkweed Species
Milkweed can adapt and thrive in various growing conditions, so it’s perfectly possible even for beginners to grow them.
What’s more, planting milkweed in your garden means providing shelter and food to the butterfly populations that depend on them.
The most common milkweed species you can grow in most states are the butterfly weed, swamp milkweed, whorled milkweed, and the common milkweed.
The butterfly weed blooms from May through September, displaying bright yellow or orange flowers.
Like the butterfly weed, whorled milkweed produces flowers from May through September, but this species has greenish-white blooms.
These milkweed species prefer dry conditions, so plant them alongside each other for a more decorative display.
On the other hand, if your area is more moist than dry, you can grow swamp milkweeds instead.
This species is famous for its deep pink to rose-purple flowers that bloom from June to October.
Of these four, the common milkweed’s pink or purplish flowers are the most fragrant and will bloom from June to August.
Since it can thrive in average garden soil, beginners prefer this species over the others.
The best species to grow in your garden is the one native to your area. This way, it won’t have a hard time adjusting to the climate.
How To Plant Milkweed Seeds
As mentioned, milkweed seeds need to undergo vernalization, which is when seeds are exposed to the cold for extended periods.
This is why it’s advised that you plant seeds in the fall so that they go through the process naturally.
On the other hand, you can simulate the conditions indoors and have them ready for replanting once the danger of frost has passed in spring.
That said, these plants have deep root systems, so they don’t like being transplanted.
Here’s what you should do when growing milkweed from seeds:
Step 1: Starting seeds indoors or sowing directly outdoors
Directly planting outdoors in the fall is the easiest way to grow milkweed from seeds.
However, if you decide to start them indoors in spring, you need to wake them up from dormancy via cold stratification.
To do this, plant the seeds in a container with moist soil and then cover them with a plastic bag. For at least three weeks, leave the container in the fridge.
Alternatively, you can put the container under grow light until the ground warms up in about six weeks. Make sure you keep the soil moist but not soggy.
In their dormant state, milkweed seeds won’t sprout and produce young leaves as quickly as other perennials. Instead, all the energy is focused on establishing strong roots.
To sow directly in your garden, scatter the seeds on the soil surface about half an inch apart.
Then, cover with 1/4 inches of soil before watering. Again, ensure the soil is moist to help the seeds sprout.
Timed correctly, your seedlings will have established strong roots to survive the cold of winter.
Step 2: Transplanting seedlings outdoors
You’ll know the seedlings are ready for transplanting once you see two sets of leaves sprout or when the young plants are about three inches tall.
By then, you can go ahead and move them to a sunny spot in your garden. They will do well in areas that receive at least four to eight hours of sun every day. Dig a hole that is twice the size and depth of the young plants’ root ball.
The top of the root ball should be even with the soil’s surface.
Plant them in rows, and make sure you give each seedling two feet of growing space.
Then, water each milkweed plant deeply to compress the soil, which should also remove any air pocket.
Step 3: Planting alongside other sun-loving plants
If you wish to invite more beneficial pollinators to your flower garden, you can plant milkweed alongside other ornamentals.
They will look stunning when grown with prairie dropseed, goldenrod, black-eyed Susan, and the Arkansas blue star, for example.
How To Care for Milkweed Plants
Milkweed plants can grow anywhere from two to six feet tall. The leaves will grow from thick and strong stalks, so there’ll be no need for stakes.
As the plant matures, the green stems will take on a reddish color and become hairy and hollow.
Around this time, the pointed, waxy, and dark green leaves will also drop from the stalks, which is when the milky substance appears.
To ensure the best growing condition, here are milkweed care tips to keep in mind:
1. Water every day until roots are established.
You will want to water your seedlings each day to support their development during their early stage.
Again, the goal is to keep the garden bed moist instead of soggy, so make sure you water lightly. The best time to do this is in the morning.
2. Figure out the right amount of water for growing milkweeds.
More often than not, your milkweed plants won’t need watering once they’re fully established.
This is especially true if you’re growing butterfly weed, whorled, and common milkweed, which prefer dry environments.
However, you can’t say the same about swamp milkweed.
As the name suggests, this species will grow best in moist soil, so give it regular watering but ensure good drainage at the same time.
3. No need for fertilizers.
Fortunately, this herbaceous perennial does not require fertilization. In fact, it can thrive even in pool soils.
That said, you’ll want to watch out for spreading rhizomes. Given the right growing conditions, your milkweed plants will start spreading around year three or four.
If you don’t want them spreading all over your garden, you can control the spread by growing them in raised beds.
4. Remove withered flowers.
By removing flower clusters once they’re done blooming, you’re allowing the plant to focus its energy on producing new buds.
This way, more flowers with their sweet nectars become available for monarch butterflies and other visiting pollinators.
5. Mulch only if needed.
Mulching helps retain moisture, so it might not be the best idea if you’re growing milkweed species that love dry soil.
On the other hand, use fine-chopped bark or leaf litter as mulch for swamp milkweed, which should help control weeds at the same time.
6. Harvest seed pods in early fall.
Aside from rhizomes, your milkweed plants will produce seed pods.
Come early fall, you can collect milkweed seeds and replant them or give them away to neighbors and family.
The pods will split open if you don’t, and the seeds will spread throughout your garden.
7. Keep pests at bay using only water.
Fortunately, there are no known diseases or pests that target milkweed, though some get infected with whitefly or aphids.
In such cases, you can use water to wash them away.
Ultimately, the main purpose of growing milkweed is to house monarch butterfly eggs and caterpillars, so make sure you don’t hose them off.
To be safe, you can manually move already-hatched larvae before you water down the plant.
We also don’t advise using pesticides so as not to harm the butterflies and their eggs and larvae who have found their home in your plants.
8. Wear protective gear when handling milkweed.
Another interesting thing about milkweed is that the same substance that feeds monarchs can harm humans, pets, and other animals.
The milky sap contains toxic alkaloids, which can result in skin and eye irritation. It’s also poisonous when ingested.
That said, you will want to wear long pants, long sleeves, and gardening gloves when tending to your milkweed plants.
Because milkweed seeds take their sweet time to sprout, a lot of beginners may get discouraged.
The key is focusing on the end goal, which is to support the monarch butterfly population in your area.
Not only will you be helping these beautiful creatures multiply but also add a gorgeous display of colorful flowers to your garden.