Planting Milkweed Rhizomes

I planted 30 milkweed rhizomes on Thursday (February 16th), a major step in my 2023 monarch butterfly raising project. Rhizomes are thickened underground stems that store starch for plants. Rhizomes can send down roots and send up stems. In the late fall, all of the above ground foliage on milkweed plants dies. The milkweed rhizomes then overwinter underground. In the spring, they provide the energy for the plant to sprout. Some types of milkweed also spread via their rhizomes. The underground stems grow horizontally and, over the years, the plant will form a clump with many above ground stems. 

In fall of 2022, I had 66 milkweed plants growing in planters of various volumes, from around 25 gallons down to small, 6” planters that only hold about a quart. I decided to leave the rhizomes in “large” planters — which I defined as 3 gallons or larger — in their potting soil. This is what I’ve done most years. 

Left: Milkweed rhizomes wrapped in damp paper towels and stored in a ziplock bag. Right: Milkweed rhizomes unwrapped and ready to be planted.

However, over the winter, I tipped out all of the small planters and fished out the rhizomes. There were 30 such containers. I wrapped the rhizomes in moist paper towels and put them in ziplock bags. The bags were kept in the refrigerator. I have done this successfully a few times in previous years, so I knew it would work. 

The reason I did this was to move the milkweeds to larger planters. Moving them as rhizomes, I believe, is better than waiting for them to sprout and moving them as growing plants. 

Left: Five-gallon planters holding the rhizomes. You can also see some of the 2-gallon planters on the right edge of this photo. Right: Three-gallon planters holding milkweed rhizomes.

The rhizomes themselves ranged in size. I planted the 6 largest in 5-gallon planters. I planted the next 5 largest in 3-gallon planers. The rest went into 2-gallon planters, so some may not have gotten a larger container. Most did, however, as some of my planters were quite small. 

Planting the rhizomes was easy, I just sunk a trowel into the potting soil and pushed some soil aside. I placed the rhizome vertically into the hole created by the trowel and then removed the trowel. If the top of the rhizome was sticking out of the soil, as it usually did, I added a little more potting mix to the top of the planter. 

The temperature inside the refrigerator was around 40 °F. The low temperatures Thursday and Friday night were in the low 30s °F. So the rhizomes got a final couple night’s worth of cold temperatures. Now, they will start to warm as the forecast calls for a lot of days in the 70s–80 °F and nights in the 50–60s °F coming up. If the last 10 years are any indication, the milkweeds should start sprouting in mid-March — right around the time of the average last frost. 

Soon, I will have milkweed plants.

My 2023 Monarch Raising Project (III: Disease)

[During the spring of this year, I hope to raise and release 240 monarchs. This is the third post in a series about my monarch butterfly raising project. The first post in this series dealt with growing milkweeds, the host plants for the monarch butterfly. The second post dealt with native flowers to attract the butterflies. This post is about dealing with the possibility of disease.]

In order to raise and release 240 monarchs butterflies, I will need to grow a large amount of milkweed in a fairly small space. I will also have too rear the butterflies in close quarters inside my butterfly enclosures. Anytime any species is found at a high density, the possibility for a disease to spread through the population is present. 

In order to minimize the possibility of a disease outbreak, I will need to do two things — monitor the plant and butterfly populations for diseased individuals and isolate them. It would be great if I could prevent all of the diseases that affect milkweeds or monarchs from arriving, but that isn’t possible. Insects arriving in the garden bring many diseases. Spraying insecticide to kill these insects is not an option because that would also kill the monarchs. Likewise, netting the plants would keep insects off them, but that would include the monarchs. So, I can’t prevent the arrival of insect-borne diseases. With that being the case, I need a plan to deal with insect-borne diseases, should any arrive. I can prevent fungal diseases by avoiding overhead watering and pruning the plants to increase airflow around them, if needed. 

One piece of good news is that I’ve never had a problem before. By the end of every season, my milkweeds are infested with milkweed aphids and milkweed bugs. And sometimes, their leaves get a bit mottled (suggesting some sort of disease). However, every spring the milkweed returns and is healthy. I’ve also never detected any problems with disease among the monarchs. I’ve had tachnid fly infestations, but I deal with that by raising the caterpillars in netted enclosures. 

My plan for dealing with disease is to monitor the plants and the butterflies (larvae and adults) for potential problems. If I detect a problem, I will isolate (or destroy) the diseased individuals. If a plant looks ill, I can simply remove it from the garden — hopefully before whatever it had spreads to other nearby plants. Likewise, if I see a caterpillar that looks ill, I can remove it from its enclosure and not add any new monarchs to that enclosure. I have several, so I can rotate through them and sanitize used enclosures before using them again. 

To make disease less able to spread quickly, I will also physically spread out my milkweed plants as best I can. This may not help much if an insect-borne disease arrives, as insects could easily fly from one side of my yard to the other. But it will help with any disease which spreads faster with physical proximity. I will also raise the monarch caterpillars in as many different enclosures as is feasible. That way, if an individual becomes diseased, the disease could only be spread within its enclosure — which could be sanitized before being used again. 

Other than tachnid flies, one of the biggest threats to monarchs is the protozoan Ophryocystis elektroscirrha (often simply referred to as OE). Given the seriousness of OE, I’ll devote an entire post to how I will deal with this, should it arrive in my garden. One of the major things gardeners can do to avoid an OE infestation is not grow non-native milkweed. All of my plants are natives, so that’s not a problem. But, the disease is still worthy of serious consideration. 

At the time I am posting this, it is about 5 weeks away from the milkweeds sprouting and maybe 6 or 7 weeks from the monarchs arriving at my garden in central Texas. I have a lot of milkweed seed cold conditioning (stratifying) right now and I also have several milkweed rhizomes in my refrigerator. These are in addition to the milkweeds in my container garden planters. Things should start heating up in early March. If you’re interested, I hope you follow me on my quest to 240.

My 2023 Monarch Raising Project (I: Milkweeds)

In North America, there are essentially two main populations of monarch butterflies (Danaus plexippus). The largest population overwinters in Mexico and migrates to the northern United States — from North Dakota to Maine — and southern Canada each year. The second population overwinters in southern California and makes a shorter migration up the West Coast. Additionally, smaller populations of monarchs live in Florida or overwinter in scattered locations along the Gulf Coast.

The number of butterflies overwintering in Mexico has been trending downward since the 1970s. Milkweeds (mostly plants in the genus Asclepias) are the only host plant for monarch butterflies. Many gardeners, like myself, grow milkweed in order to provide food for monarch caterpillars. A combination of milkweeds and other native flowering plants also provides food for bees, other butterflies, and hummingbirds.

The number of monarch butterflies has been declining since the 1970s.

In 2021, I raised and released 77 monarch butterflies. My goal for 2023 is to release 240 — roughly three times as many. The reason for 240 is that for many years I raised roughly twice as many monarchs as the year before — from 7 in 2016, to 15 the next year, 30 the next, and then around 60 in 2019. To fit the pattern, I “should” have raised 120 in 2020. But there was a pandemic and other factors intervened and I only raised around 30. So, for 2023, I want to get back to the doubling — if only for a year.

To hit this target, I figure that I need four things:

1.) Sufficient milkweed to feed the monarch caterpillars

2.) Enough blooming flowers to attract the adult female monarchs

3.) To suppress any disease outbreaks in either the milkweeds or the monarchs

4.) A little luck

In this post, I will discuss the milkweeds.

In 2021, I had roughly 40 milkweed plants in my garden. These ranged from plants I had grown for many years to first-year seedlings. By the time the 77th butterfly was released, I was running low on milkweed. Using this information as a start, I figured that I would need at least one milkweed plant for every two monarchs I plan to raise. This should give me enough milkweed with a little excess. This year (2022), I have around 70 plants and I easily have enough seed for 50 more. That should be sufficient milkweed.

Milkweed is the host plant for monarch larvae (caterpillars).

In past years, I would look for monarch eggs or monarch caterpillars on my milkweeds when the monarchs were migrating through my area. I would then pick the leaf the insect was on and place it in one of my butterfly enclosures. Unfortunately, this wasted a lot of milkweed. When small, the caterpillars won’t consume an entire leaf overnight. By the next day, they want a fresh leaf. So this year, I plan to conserve leaf material by taking a pair of scissors and cutting around the egg or caterpillar. I’ll then lay that bit of leaf on a small plant in an enclosure. When the caterpillar abandons the leaf cutting, it will find itself on a milkweed plant. I can rotate partially consumed plants out of the enclosures to let them recuperate for awhile before using them again. Milkweeds are very resilient with regards to caterpillar damage. This should give me a little more leeway with regards the amount of milkweed biomass I need.

Adult monarchs will feed on the nectar of many native plants, such as these.

In a few days, I will discuss the other plants I will be growing for my monarch project. Milkweeds are the host plant for monarch caterpillars, but adult monarchs nectar on the the flowers of many plants. I have a plan to provide multiple types of flowers — blooming at multiple heights — throughout the monarch migration. In spring, I will update this website often on the progress I have made. At my location in central Texas, milkweeds start sprouting in late March and “monarch season” usually lasts from April through June.

Newly eclosed monarchs in a mesh enclosure, about to be released.