In our last post, we talked about Blue lobelia and how it evolved over time to form a very specialized relationship with bumble bees. There are other plants that have evolved more broadly, and are used by many different insects. Our native goldenrods are a great example of this.
Wait! Not that weed we see growing along all the roadways and in abandoned fields!? Doesn’t that cause hay fever? It turns out goldenrod has gotten a bad reputation and has been confused with ragweed. Unlike ragweed, goldenrod pollen is not airborne and can’t be the culprit of our late season scratchy throats and sneezing. There are over 2 dozen types of goldenrod native to New York State, some of which make very good choices for our more ornamental gardens. And they all support, or host, over 100 caterpillars – more than any other of our native perennials.
Host plants are plants that provide food sources for certain caterpillars. Caterpillars are the larval stage of butterflies and moths, or Lepidoptera. They consume a large amount of plant material and grow quickly – for instance, a tobacco hornworm will increase its weight ten-thousandfold in less than twenty days. This is an essential step in becoming adult butterflies or moths. Some caterpillars are extremely finicky, like the monarch caterpillar, who only eats milkweed plants. Others aren’t so picky, and many of them
Wavy lined emerald moth
eat goldenrod, like the Wavy lined emerald moth, making goldenrod a great host plant for us to use in our gardens if we want to support butterflies and moths.
The goldenrod we see everywhere growing as a “weed” is most often Canada goldenrod (Solidago canadensis). It is happy in sunny, moist sites and is also a bully, crowding out other plants. (Think of all the butterflies that are happy to take advantage of this the next time you see it!) However, there are other types of goldenrod that are more compact, like some shade, and are quite pretty.
Blue-stemmed goldenrod
At FT Proctor Park, we planted 2 types of goldenrod in the new woodland garden in the North circle – Blue-stemmed goldenrod (Solidago caesia) and Zig Zag goldenrod (Solidago flexicaulis). Blue-stemmed goldenrod prefers part shade and medium soil, but will tolerate full sun. It grows 3 feet tall and has graceful arching stems with unique, blue green foliage. Zig Zag goldenrod prefers part to full shade in medium soil, grows 2 to 3 feet tall and spreads by rhizome, making it a good groundcover. Both spread slowly and are drought tolerant once established.
Zig zag goldenrod
These goldenrods bloom in late summer and into fall, making them essential pollen and nectar sources for bees before winter hibernation. Migrating butterflies like the monarch rely on their nectar for energy as they fly south for the winter. Their seeds are eaten by songbirds. Goldenrod is more than just an essential host plant for butterflies and moths, it supports many species in a variety of different ways. We hope you will come see it next summer in FT Proctor Park and consider adding a variety or 2 to your home gardens.
To learn more about goldenrod, visit the Tufts Pollinator Initiative
Photos courtesy of the Lady Bird Wildflower Center
