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In Carlsbad, the West Coast monarch does not migrate, but rather is known as the “resident monarch” and will lay green eggs on native milkweed and nectar plants such as butterfly bush and cosmos. Courtesy photo
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Jano’s Garden: The monarch question

As a child growing up on the shores of Lake Michigan in Wisconsin, I was always amazed in August and September when the monarch butterflies came through our tiny town of Cedar Grove.

We spent the summers at a small cottage, and on our morning beach walks we would try to rescue some of the hundreds of orange and black butterflies that had just completed the 200-mile journey across the choppy waters of the lake.

Little did I know then, that these migratory monarchs had actually flown all the way from Northeastern Canada, and our little town was just a stop on their long journey to Mexico.

Now that I live in Southern California, I am encountering this wonderful insect once again, and have found many adult females laying their eggs on milkweed in the Carlsbad area.

In a few weeks, green-striped caterpillars emerge and in another few weeks, all of my gardening friends and I have noticed lots of monarchs flying around North County.

But, after doing research with the Xerces Society, some disarming and sometimes contradictory facts have emerged. The West Coast monarch does not migrate, but is known as the “resident monarch.”

“The growing body of research has found that resident monarch populations using year-round milkweed have a higher rate of the disease OE (Ophryocystis elektroscirrha). For this reason, Xerces recommends an approach guided by the precautionary principle: plant native milkweed species in their natural ranges to help monarchs. In general, native milkweed species in their natural ranges die back once per year, thus breaking the cycle of disease, whereas the non-native milkweed species that grow year-round serve as constant reservoirs of disease.” (www.XercesSociety.org, March 2021).

Since I consider part of my job as a Master Gardener and writer is to keep both backyard and professional gardeners abreast of the latest updates horticulture, I researched the local San Diego Master Gardener website. (www.mastergardenersd.org)

“Nonnative milkweed was first introduced into the United States from South and Central America in the last century. Because it doesn’t go dormant in the winter like native milkweed, it has upended the historical relationship between monarchs and native milkweed. When native milkweed is dormant, there are few monarchs in San Diego during the winter, other than some over-wintering butterflies along the coast.

“However, there is a compromise if you have nonnative milkweed in your garden. Cut it back and keep it at 6 inches tall over the winter to mimic native milkweed’s dormancy. Remove all plant debris to get rid of any OE spores.” (Judy Wolinsky, San Diego Master Gardeners).

Many of the small, local nurseries are now selling native milkweed grown at Moosa Creek Farms, in San Marcos. Their high quality varieties include narrow leaf milkweed, California milkweed and desert milkweed.

I recommend the following nurseries that provide both native and tropical varieties. Anderson’s La Costa Nursery in Carlsbad; Green Thumb, San Marcos and Butterfly Farm in Encinitas. The staff at all of the sites will be happy to assist you in planning your butterfly garden.

Although many gardeners, including myself, have previously thought, Monarchs do not just need milkweed for egg laying, but nectar plants as well. The milkweed provides the perch on which the eggs can rest, but does not produce nectar.

The nectar plant choices to attract adult monarchs are butterfly bush, cosmos, lantana and native sages, pentas, Mexican Sunflower, Gaillardia and delphinium. My advice to all novice gardeners is to make lists and take them with you when you go to a garden centers.

A local exhibit and nursery can be found at Butterfly Farms in Encinitas. Their plant-filled greenhouse is filled with a wide variety of butterflies and well stocked with the varieties that the butterflies enjoy calling their home.

The well-trained staff is happy to answer questions, and customers quickly fill up the wagons provided with recommended variety of perennials and annuals. I highly recommend purchasing perennials since they will multiply and return the following year.

The question of “native or non-native milkweed,” will continue to be researched by both the Xerces Society and the Master Gardener Program, and we will keep you abreast of all the latest information. Be sure to talk to the staff at your local nursery when purchasing your plants, and have fun watching the butterflies emerge in your yard!

Please contact me with any gardening questions you may have at [email protected].

Jano Nightingale is a Master Gardener and horticulturist and lives and works on community gardens in North County.

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