Our state insect, the monarch butterfly (Danaus plexippus), is the only butterfly that makes a two-way migration, traveling south to Mexico in the fall and returning north in the spring.
Since the 1950s, its population has been declining in Illinois. The good news is this past winter, the number of monarchs overwintering in Mexico was up 144%. What can we do to help keep their numbers up? Plant milkweeds.
Monarch caterpillars must eat milkweed plants to survive. Lucky for us, there are 22 species of milkweeds native to Illinois to choose from. Many are smaller and more delicate than the common milkweed (Asclepias syriaca), the tall, 4-to-5-foot, rangy plant with fragrant pink flowers that we see on roadsides. Here are five milkweeds that have eye-catching flowers, are drought resistant, and grow in dry to medium soil in full sun unless otherwise noted.
Butterfly milkweed (A. tuberosa), the 2017 Perennial Plant of the Year, is the showiest of all the milkweeds. The yellow to orange flowers bloom June through August. Butterfly milkweed grows 1 to 3 feet tall with narrow, lance-shaped leaves.
Showy milkweed (A. speciosa) is a more delicate version of the common milkweed. It has purplish, fragrant flowers in early summer. It grows 1 to 3 feet tall with oval leaves.
Eastern whorled milkweed (A. verticillata) has fragrant, white flowers June through September. It can tolerate partial shade. This plant grows 1 to 2.5 feet tall with needle-like leaves arranged in whorls along the stem.
Green milkweed (A. viridiflora) produces green flowers in summer. It can tolerate moist sites. Leaves from plants grown in wetter areas are more rounded than those of plants grown in drier areas. Overall, green milkweed grows 1.5 to 2 feet tall.
Rose or swamp milkweed (A. incarnata) has fragrant, pink to mauve flowers July through August. It can reach 4 to 5 feet. As its name implies, it is found in wet areas, but is very tolerant of average, well-drained soils. It has narrow, lance-shaped leaves that taper to a point.
During World War II, children were called to collect milkweed pods for the government. The floss (hairs) that help disperse milkweed seeds was used to fill life preservers when the usual filler became unavailable. Now you can choose from many milkweeds to grow a life preserver for the monarch butterfly.
Sue Styer is a University of Illinois Extension master gardener for Kane County. The “Learning to Grow” column runs weekly during warmer months of the year. Call the extension office at 630-584-6166 for more information. Feedback on this column can be sent to firstname.lastname@example.org.