Milkweed Bush Guide: How To ID, Grow and Plant Perennial Milkweed Flowers

Image Credit: Lasclay⁷

How To Identify Milkweed Bush (Milk Weed)

The Milkweed bush grows to about 6 feet tall depending on the species and you will usually see them in strong, thick clusters.¹

Their thick rhizome stems mean they grow fast and quickly form colonies.

Milkweed Bush Leaves

Milkweed bush leaves are 6 to 8 inches long and about 2 to 3.5 inches wide. The top surface varies from light to dark green and the bottom is very pale, sometimes almost white.

Leaves grow on stems in pairs opposite each other.

Milkweed Bush Flower

The Milkweed bush flower grows at the top of the plant in sphere-shaped clusters, with each plant typically having between two and five clusters.

Blooms are .75 inches long and .4 inches wide in various shades of pink such as rosy-pink and purplish-pink. They have a very strong, sweet scent.

Milkweed Bush Fruit

After flowering, Milkweed bush fruit grows in the form of pods 3 to 5 inches long. They start off green and turn brown as they mature.

The pods are inflated and have finger-like growths protruding from them.

Milkweed Bush Seeds

Milkweed bush seeds are small, flat, and brown and each pod contains anywhere from 50 to 200. Each seed has fine, silky hairs attached to it to aid in wind dispersal.

Milkweed Bush Growing Zone

Milkweed is a pretty hardy, adaptable plant so when it comes to where to grow, it can thrive well anywhere from the coldest zone of the continental US to some of the warmest areas of the country. The official growing zones for Milkweed bush range from 3 to 9.⁴

Milkweed Bush Growth Rate

As for how long it takes to grow Milkweed bush, it can take some time to become established. The first year of growth is devoted to the roots becoming more established.

It will start producing more foliage during its second year of life, and Monarchs may start feeding on it at this point.

The Milkweed bush does not produce flowers until its third year. At this point, the plant has matured.

Best Time To Plant Milkweed Bush: Growing Milkweed Bush From a Seed

As for when to plant Milkweed bush for the best yield, that would be fall.⁵ The seeds need cold treatment to properly germinate, and planting them during this time means they will get the appropriate cold and moisture from the winter weather.

They need to go through a natural process of being frozen and then thawed out to soften the outer coating.

Planting in the spring is possible if you recreate the conditions necessary for germination by putting the seeds in moist soil or between two moist paper towels in a ziploc bag and placing them in the fridge.

If starting the process indoors, start growing the seeds one to two months before you plan to place them outside. Do not plant them in the ground until the last frost has passed.

Considerations For Planting

Because the plant will spread extensively under the ground, it is important to carefully choose the spot where the seeds will grow. You can either place them somewhere they will have the complete run of the space or you can place a barrier around them to contain the rhizomes.

There is also the option to move them eventually but this can be more difficult with Milkweed.

Best Growing Conditions for Milkweed Bush

Here are some helpful planting tips for Milkweed bush:

Sun

How much sunlight does Milkweed bush need each day? This plant thrives best with lots of light so it is best planted in an open space that gets at least six to eight hours a day.

Water

The watering needs for Milkweed bush plants will vary depending on whether the plant is still growing or has become fully established. During the plant’s first growing season, always water when the top inch or two of the soil feels dry.

The particular conditions of your environment will determine how quickly this happens, but generally, it will probably need watering every few days during this time.

After the first growing season where the plant has become more established, they become quite tolerant of drought and dry conditions. If the soil is dry several inches down, it needs a drink.

(Image: Jenifer Kramer (jlkramer)⁸)

Overwatering the plants makes them vulnerable to deadly fungus. One of the most common signs of overwatering are yellowing of the tips of the leaves, which may travel towards the stem.

Soil

This hardy, adaptable plant grows well in most types of soil, including that which is rocky, infertile, or nutrient-poor. But regardless of the type, the dirt must be well-draining.

If Milkweed is grown in soil that stays wet for long periods, it is vulnerable to root rot and other problems.

The most ideal pH range is 4.8 to 7.2

Fertilizer

Because the plant is not vulnerable to poor soil conditions, Milkweed doesn’t require fertilizer to provide any particular nutrients it may not contain.

Spacing

How far apart to plant Milkweed bush will depend on the species. Generally, the best distance between each plant is about 18 inches.

Because Swamp Milkweed grows in clusters that can spread about 3 feet wide, it is best to plant this variety about that far apart from each other. Though you can plant them closer together and thin out the plant as it grows.

Pruning

Milkweed doesn’t require much pruning. It will die back in the fall and start regrowing again in the spring.

Some people choose to remove the flowers once they have faded in the late summer to prevent pods from forming. If there are no pods, there are no seeds to be disseminated, which inhibits growth in the area.

Companion Plants For Growing Milkweed Bush

There are a number of companion plants for growing Milkweed bushes. Companion plants serve a number of purposes in an outdoor space from making it more attractive to using it more efficiently.

When it comes to Milkweed, the primary purpose of companion plants is to create really attractive color combinations. Purple or blue perennials like asters or meadow sage go great with the orange and gold flowers of the Butterfly weed.

(Image: Jan Haerer (leoleobobeo)⁹)

Other good choices for perennials include Goldenrod, Black-eyed Susan, Coneflower, and Bee Balm.

Ornamental grasses also pair nicely with Milkweed by providing a nice contrast in textures. Good choices include Carex, little bluestem, or prairie dropseed.

How To Stop Milkweed Bush Disease

When it comes to how to stop Milkweed bush disease, the good news is this hardy plant isn’t particularly vulnerable to any serious diseases.

The most common pests of the Milkweed bush are the small Milkweed bug and the large Milkweed bug,⁶ and while they may feast on this plant plenty, especially the seeds, they actually don’t do all that much damage, meaning not all that much needs to be done about them.

Other bugs that may feed on the plant include beetles and aphids.

When it comes to natural pest control for Milkweed bush and milkwood bush disease prevention, insecticidal soaps may help as well as simply removing leaf remnants and old stalks from around the plants. Be sure not to overwater the plants to prevent fungal growth.

4 Types of Milkweed (Milkweed Plant)

There are over 100 different types of Milkweed native to the United States, Canada, and Mexico. Here are a few of the more common types likely to show up in the average garden:

It can have pale purple flowers or pink flowers that are very fragrant and attractive to the Monarch and various pollinator insects.

This species of Milkweed bush is particularly aggressive and you want to plant it somewhere that has plenty of room to spread out and won’t overtake nearby plants in your backyard garden.

Like its name suggests, it thrives best in areas with more moisture like marshes lakeside land.

4. Showy Milkweed

Showy Milkweed will be found west of the Mississippi all the way out to California and north into Canada. This species typically grows 2 to 4 feet and has pastel pink flowers.

Highly tolerant to drought, it is a particularly good choice for the dry plains and prairies. But it will grow just fine in more moist conditions.

Why People Grow a Milkweed Garden

As mentioned earlier, many people grow a Milkweed garden specifically to provide a food source for Monarch caterpillars. But this plant is a nutritional superstar, with over 450 known insects feeding on it.

The flowers are rich in nectar and you will see all sorts of bugs flocking to them such as bees, wasps, beetles, flies, and ants. Besides nectar, other parts of the plant used for food include the actual flowers themselves, sap, and leaves.

Is Milkweed Poisonous to Any Creatures?

Is Milkweed poisonous to any creatures? Being that almost 500 insects feed on this plant, it might be surprising to hear the answer is ‘yes.’

It is actually quite poisonous to the majority of insects and other creatures due to the presence of cardiac glycosides, substances that are extremely toxic to most living things.

For many insects, having the glycosides in their tissue offers a very effective defense mechanism against being eaten. The Monarch butterfly and caterpillars are one such animal using this defense.

Considerations For Planting Milkweed Bush for Monarchs (Best Milkweed for Monarchs)

There are some important considerations for planting Milkweed if you want to establish a habitat for Monarch butterflies and attract bees and other pollinators.

Only plant Milkweed bush that is native to your area. There are numerous species of the plant that grow across most parts of the country, except Hawaii, Alaska, the northwest of Oregon, and the western part of Washington state.

You can find what species are native to your area by visiting the Biota of North America Program’s website.³

The availability of seeds varies depending on the part of the country, providing a habitat for the Monarch butterflies is the most common reason people are interested in this plant, and they are more common in some areas than others.

Of the more than 70 species of Milkweed bush native to the US, only about 20 species are usually available commercially.

If you cannot procure seeds for Milkweed plants native to your region, you can still do your part to help Monarch butterflies by planting native wildflowers for the adult Monarchs to feed on.

These plants will also attract beneficial pollinator insects. You can see which plants are best by region by visiting USDA’s website.²

Having this plant in your garden can do a great service to Monarch butterflies and the environment in general by attracting large numbers of pollinators.

Growing and caring for Milkweed bush is relatively simple, and just be sure to plant varieties native to your region so they flourish.

Frequently Asked Questions About Milkweed Bush