Milkweed: A Monarch Friendly Garden

gardeninggarden seminarpollinator gardenmonarch butterflyflower
Written By Catharina Soesetyo

Excerpt from the Seminar on April 16, 2022 at the Glendora Gardens Nursery. Scroll down for resources and PDF.

The Monarch butterflies migration and their population are on the news every year. It is significant, because scientists use the data to monitor climate change, and forest (deforestation) and land (farming & pesticides usage) management practices . In our continent, the Monarch butterflies migrate between Southern Canada and Mexico - they travel South in the Winter, then back North in the Summer. 

Do you know that the Monarchs that migrate are called the Super Generation? Do you know why? Bigger, live longer (7-8 months) and travel from Southern Canada to Mexico. That is about 3000 miles.

What makes a garden specifically Monarch friendly?

Monarch Butterflies on Tropical Milkweed

Monarch carterpillars feed exclusively on milkweed leaves and parts of the plants. To make a garden monarch friendly, it should also have milkweed plants in addition to other pollinators’ favorites.

Let’s talk about milkweed

It is called “milkweed” because of the milky sap in the stems and leaves. This sap is toxic to most insects and animals, except to monarch caterpillars (and a few other insects that also feed on milkweed).

Caution when handling milkweed - the sap could cause skin irritation, and be very dangerous if it gets into the eye. For one, it will be painful, it can cause symptoms such as blurred vision, light sensitivity and to some extreme cases, part blindness. So please, handle with care when pruning or handling the plants. 

Native vs Non Native

Narrowleaf Milkweed - Asclepias Fascicularis

There is an ongoing debate about growing native versus non native milkweed, especially here in Southern California, and in regions where they hardly get frost and annuals sometimes grow like perennials. 

Native milkweed are perennials. For Southern California, native milkweeds have very narrow leaves. The ones commonly seen is aptly named, Asclepias Fascicularis or Narrowleaf Milkweed. Dainty with beautiful soft white-pinkish flowers, they may not look much, but surprisingly enough for the monarch butterflies. Native milkweed dies back in our Winter, only to spring back to live again as the weather warms up.  Non Native milkweed, such as the Asclepias Curassavica or Tropical Milkweed, continues to grow despite the drop in temperature, at least here in SoCal.

Monarch butterfly deformed and did not eclose successfully.

The concern lies with the spread of a protozoan parasite that is affecting the monarch butterfly population. It is called Ophryocystis elektroscirrha or OE for short. This parasite lives on the milkweed plant and reproduces inside a living monarch butterfly. OE infected butterflies have a high chance of not eclosing (emerge from the chrysalis) properly, or have deformity. If they look healthy, they become carriers. The parasites are carried as spores on the wings or on the belly area. When the butterfly visits a milkweed plant, the OE gets transferred via the leaves, stems or flowers. The caterpillar eats, the parasites get eaten. The caterpillar then turns into a butterfly infected with OE. The infected butterflies, if it successfully transformed, pass the parasite on to their offspring, or become a carrier. And the cycle continues. 

The OE spores get deposited on the surface of the plants (the leaves, stems, flowers), and, thank heavens, they are not sticky. A good rain or rinse with a garden hose of the plants in the beginning of the year should clean them off easily. 

Now here's a thought about non native milkweed

Tropical Milkweed - Asclepias Currasavica

The Tropical Milkweed, which is also called Mexican Butterfly Weed, is growing year round in Mexico! This type of milkweed is what mainly feeds and hosts the eggs for the migrating butterflies. In SoCal, we have an interesting Monarch situation. In addition to being on the migration route, we also have non-migrating Monarchs - the ones that over winter and never left. The SoCal resident Monarchs depend on the Tropical Milkweed during the Winter months when the native varieties die back.

Here’s another amazing fact about Monarch butterflies. The migrating monarch butterflies experience diapause - an auto-biological switch in their physiology that pauses egg production during migration. Remember, these butterflies live for 7-9 months and travel 3000 miles. Their sole focus is to fly across the continent and reach the destination.

The resident monarchs never hit diapause. They continue to lay eggs as usual, until the temperature drops significantly.

Do we then stop growing non native milkweed? 

Here’s a suggested way to grow non native milkweed and keep the OE spread to a minimum. If you choose to grow non native milkweed, be sure to cut back the plants to 4-6” every month from November to February. Removing all foliage. Not to worry, milkweeds are resilient and don’t die easy. In fact, because of this heavy pruning, the plant will spring back to live even fuller and healthier.

So do you absolutely need to cut back your Tropical milkweed each year? 

The jury is still out on that one. No scientists can agree on this and each year new findings and new theories pop up. 

I love what Craig Oveson, said about Monarch and Milkweed, “Just plant milkweed!”  Craig is known as "Craig the Butterfly Man” is the Butterfly Expert at Houston Interactive Aquarium and Animal Preserve.

So, what type of milkweed are you going to plant?

Personally, I plant both natives and non natives. I want a garden with good varieties of pollinator plants and milkweeds to support the Monarch butterflies - both the migrating or the resident ones.

Now that we have talked about the huge deal about non native vs native milkweed, let’s move on to caring about milkweed in general. 

Managing the seeds

Bursting milkweed seedpods

Milkweed seeds are contained in pods. As the weather warms up, the pods mature then out bursting are the seeds. Each seed has a fluff-feather-down-like sail that flies it away with the wind. If the plant is laden with caterpillars, the big “cats” (short for caterpillars) usually will eat them up like candy! If you want to save the seeds, protect the pods from the hungry chomping mouths. Small organza pouches work great for this.

Interesting fact: In World War II, the buoyancy of milkweed fluff was put to the test when it was used in military life jackets instead of kapok. In addition, the fluff has excellent oil absorbing properties and can be used to soak up spilt crude oil while repelling water.

People who worry about the spread of non native milkweed into the local flora, or simply do not want to have milkweed as ‘weeds’ in their garden, cut off the pods before they burst. Is it realistic? To some yes, to most it is not. Especially if there are more than just a couple of Tropical MW in the garden. If you are part of the concerned group regarding non-native, then best to stick with growing naive milkweed.

More leaves means more food

Regardless of the species, we all want the milkweed plants to be bushy and have lots of leaves for the hungry cats. Do the followings to encourage side growth:

  • Pinch off the top of the plant.

  • For Tropical milkweed, the annual pruning back will pretty much encourage a bushier plant each year. In addition, periodical cutting off long stems will encourage suckers to grow and help create a bushier and larger plants.

  • Deadhead or cut off the flowers (I know, they are pretty…), but for native milkweed especially, this will prolong the life of the plants and encourage leaves production.

Growing from seeds and propagation

Tropical milkweed is very easy to grow from seeds. In fact, if you have one plant in the garden, I can say for sure that you will have plenty of its volunteers everywhere in the following year. Actually your neighbors will have them as well.

Interestingly enough, other non native milkweed to our area, those that grow in the East or MidWest, are quite tricky to grow from seeds. As the milkweed there normally experienced four seasons, the seeds need to be cold stratified in order to germinate.

Propagating milkweed via cuttings, so far, I can only do that successfully with the tropicals and swamps - both are non natives to SoCal. The cuttings of these milkweed are easy to root in water or in moist soil.

Cut 6” of the stem with at least a couple of nodes. Strip off the leaves and stick the stem in a moist media (soil or starting mix). Keep it in the shade and soon you will notice the stem grows new leaves. Another way to root the cuttings is by keeping them in water about 2-3”. Once rooted, transplant the cutting into soil. 

Pests

Aphids on milkweed

The number one pest for milkweed is APHIDS. As vegetable gardeners, we are usually quick to grab our “organic spray” to protect our crops pests. Sure we can stay organic, BUT, organic doesn’t mean safe to the Monarch. 

A common example of organic pesticide used in organic gardening is Bacillus thuringiensis or Bt for short. Bt proteins are allowed in organic farming as an insecticide because it is a natural, non-pathogenic bacterium that is found naturally in the soil. It has also been found to be safe for human and most animals. Unfortunately, it is still not safe when it comes to the Monarch. Bt particles are also very fine and get carried easily by the wind. If the milkweeds are in a close proximity to where you spray Bt, chances are the wind carries some to the milkweed. 

So now what??

Milkweed especially is a magnet for aphids. More likely than not, you will see the plants covered with tiny yellow moving globules. It is unsightly for sure, but I can assure you, that doesn’t bother the cats. They would just continue eating like nothing happens. Of course, if the infestation is high, the plant’s health will suffer and the seeds viability will drop.

You can keep a close eye on the plants. Before it gets to an infestation level, rub them off, squish them, or hose them off the plant (just be careful as you might dislodge the instar 1-2 cats). Sprinkling coffee ground at the base of the milkweed helps confuse the aphids from climbing back up the plant (also deter ants to some degree - ants are farming aphids).

My suggestion is a combination of manual management and patience. It won’t take long, especially if you practice polyculture in your garden, the cavalry will arrive. Ladybugs, lacewings and hoverflies. They will feast on the aphids and soon instead of yellow mini bubbles, you will see shriveled black specks on the plants. Those are dead and dry aphids. 

Instead of purchasing pesticides, regardless they are organic, have you looked into making one your own? You know what you put into the solution and while it may not give you as quick result as Bt, for example, it is a more natural solution for addressing garden pests issues - in a way, it won’t kill every single insects beneficial or not. And in the long run, it will allow your garden to reach a balance ecosystem naturally.

Banana peel on milkweed to repel aphids.

Here’s an interesting method by the California Butterfly Lady, Monika Moore. She uses thin stripes of banana peels and places them on milkweed stems near parts where aphids like to congregate - buds/blossoms. While it doesn’t look pretty, it seems to be unappealing to the aphids as well. I haven’t tried this method personally as I opt to go with nature care.


A common bug you will see on the milkweed is the Milkweed Bugs. You can’t miss that black and orange insect, as they are also not small. No, they are not pest per se. They won’t harm the cats. They are seed eater - they are waiting for the flowers to turn to pods, and when the pods are ready, they insert their long proboscis into the pod, inject some biochem to turn the seeds into liquid then suck the seeds out. Very cool. Very weird.

True Monarch Garden is a Pollinator Garden plus Milkweed

Monarch caterpillar

The perfect Monarch garden is a pollinator garden plus milkweeds. Monarch cats usually don’t sleep on the food plant. They went away to hide. And once the caterpillars finish their feeding, they will wander away from the milkweed in search for a place to pupate. 

Hence it is important to plant a variety of different plants around milkweeds:

  • Giving plenty of areas for the caterpillar to hide from predators (Tachinid flies)

  • For momma butterflies to feed

  • Choice location for the cats to pupate (although they might just decide to pupate on the wheel well of your car, or on the garden hose…)

  • Invite beneficial insects that feed on aphids

Common pollinators' favorites that are native to our areas are: Salvias, Lupine, Showy Penstemon, Yarrow, Sage, Primrose, California Lilac.

And of course, as a Kitchen Garden Consultant, I added a few herbs in the list. One, their flowers are pretty. Two, the flowers attract beneficial insects that help control aphids. My favorite herbs to plant in the garden are: Dill, Fennel, Celery, Cilantro.

MONARCH WAYSTATION

Monarch Waystation garden sign

Monarch Waystations are places that provide resources necessary for monarchs to produce successive generations and sustain their migration. For a garden to be certified as a Monarch Waystation, it needs to meet certain requirements (see link in the resources below).  Basically, a 100 sq ft space is adequate (although smaller would be acceptable), growing at least 10 milkweed, has other plants for butterflies to feed, to take shelter and to support all stages of the butterfly life, and at least 6 hours of sun exposure, good soil, and good gardening practices. 

Once all the requirements are met, you can register your garden to be on the national registry and get a nifty plaque for your garden and a certificate of appreciation. How about that for a bragging right?

So, are you up for the challenge and create a Monarch Waystation?

This free seminar is part of monthly garden classes by Blissful Growing at the Glendora Gardens nursery.

Blissful Growing, started in 2021 by Catharina ‘Kat’ Soesetyo, a Gardenary Certified Kitchen Garden Consultant. This women owned small business serves the greater Los Angeles, San Gabriel Valley Areas, with the goal of helping others living a healthier and sustainable lifestyle starting with growing food at home.

Ready to start growing vegetables at home? Schedule your free discovery call today.

Follow Blissful Growing on Instagram. You will get faster updates on upcoming events as well as gardening related tips.

Join our Facebook community Blissful Growing Garden Party and meet others with likemind and passion about gardening.

Catharina Soesetyo https://blissfulgrowing.com
Previous

Container Gardening: Growing Tomato

Next

Growing Root Vegetables