Shared from the 4/22/2023 Houston Chronicle eEdition


Prepare for monarch season by planting native milkweed

Brandi Keller/Contributor

Giant milkweed is also called crown flower.

James Holmes/Master Gardener

Aquatic milkweed thrives in wet soil and shade.

Houston Chronicle file

A monarch caterpillar hangs onto a tropical milkweed plant, which may be harmful if tainted by OE.

Monarchs are always welcome visitors to the garden, but it is important to know your options for butterfly and caterpillar health.

Milkweed is a flowering perennial that attracts monarch butterflies and many other pollinators, such as native bees, including bumblebees and sweat bees; white-lined sphinx and tussock moths; pipevine and eastern swallowtails; syrphid flies; and long-horned beetles.

Despite the many pollinators it attracts, milkweed’s claim to fame is as the only host plant for monarch butterflies. Monarchs, along with queen butterflies and milkweed tussock moths, only lay their eggs on milkweed, instinctively knowing that once they hatch, the larval food source is underfoot.

The most common milkweed you will find in nurseries is tropical milkweed (Asclepias curassavica), however, it is losing favor quickly. It is very attractive in the garden because it is a reliable bloomer, even through mild winters, but that is also its downfall.

While many believe year-round milkweed encourages monarchs to stay in the area instead of migrating south, there is a more sinister reason to avoid it. This nonnative milkweed harbors Ophryocystis elektroscirrha (or more easily referred to as OE), a protozoan parasite that can shorten a butterfly’s life span, affect its ability to fly, or cause problems before or upon emergence from pupal stage. Repeated visits to infected plants allow buildup of OE.

If you suspect OE, consider submitting your observations to Project Monarch Health at

If tropical milkweed is already planted, cut it back to 6 inches above the soil starting in June (not the fall, as at least one expert advised) and keep trimming it back through the winter. This will help to prevent the plant from going to seed and keep it in check. Some think this does not do enough to minimize the risk of OE, and they choose to remove tropical milkweed altogether.

Go native

Native milkweeds, on the other hand, are not overused, and the leaves are more delicious earlier in the season. With more than 30 species to choose from across Texas, there is one for your conditions.

Green milkweed (Asclepias virdis) is the most common milkweed around the state. It spreads easily and grows 12 inches tall. In early summer, it has green blooms.

Aquatic milkweed (A. perennis) is one of the easiest to grow, if watered regularly. It thrives in wet soil, as well as shade. It grows 1 to 2 feet tall.

Zizotes milkweed (A. oenotheroides) is compact and tolerates poor soil. It grows 1 to 2 feet tall.

Whorled milkweed (A. verticillata) has narrow leaves and looks more like a tall grass when its white flowers are not in bloom. All parts are poisonous to livestock and horses. It spreads by seed and rhizomes, perhaps a little too aggressively for some. It grows 1 to 3 feet tall.

Butterfly weed (A. tuberosa) is grown by many for its orange or yellow flower clusters. This milkweed does not produce milk sap like others. It is the host plant for the gray hairstreak and queen butterflies. It is drought tolerant once established. It grows 2 to 3 feet tall.

Finding milkweed

Local garden centers have improved at offering native milkweeds, but if you have trouble locating them, check out your local Audubon or Native Plant Society. If you are around the Houston area, a few locations specialize in native plant sales, including Mercer Botanic Gardens, Native Plant Society of Texas — Clear Lake and Houston Audubon’s Native Nursery.

Growing milkweed from seed can be tricky. According to Master Gardener and Native Plant Society member Linda Pearson, all milkweeds, except for A. perennis, need to go through a process of cold moist stratification; otherwise, the germination rate is low.

Pearson states that some species, like green and zizotes milkweed, have taproots, so they can take a year or longer to become established and produce enough to feed monarchs. The good news is that once they are settled, they are drought tolerant.

Potted plants can go in the ground anytime, but it’s best to plant in spring.

Plant seeds in late fall. You can do so in the spring, but if there are any issues with germination, it will be too late to


For more information on native milkweeds and how to grow it from seed, visit the Native Plant Society — Houston Chapter website at

Gardening Events

MASTER GARDENER PERENNIAL & PEPPER SALE: Harris County Master Gardeners will be on hand to answer questions about plant selections. 9:30 a.m.-1:30 p.m. or while supplies last, April

22. St. Paul’s Episcopal Church, 5373 Franz, Katy. For more information:

GROWING HERBS FOR CULINARY AND MEDICINAL PROPERTIES: Herb Society member Karen Cottingham talks about the basics of planting and care of herbs, along with culinary and medicinal applications. Presented by Urban Harvest. $35. 6 p.m. April 25. Westbury Community Center, 12581 Dunlap. Register at

EDIBLE ACADEMY: GARDENING AND NUTRITION EDUCATION: Carol Burton, director of permaculture with Urban Harvest offers a professional development workshop for teachers, parents and community supporters. The three-hour workshop will explore garden basics in the garden and outdoor classroom. $40. 9 a.m.-noon April 29. Milby High School, 1601 Broadway. Register at

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