Beautiful Native Plants


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Sunday, December 22, 2019

Giant Ironweed, a Tough, Eastern North American Wildflower

Many butterflies visited the new ironweed including this  
beautiful giant swallowtail (Papilio cresphontes).

Why do we love native wildflowers in our yards? 


It's the butterflies, the birds, and the bees. As Doug Tallamy says, the plants in our yards need to do more than just be pretty. They should support wildlife and become part of the local ecosystem. And the best way to do this is to have a wide variety of native plants. This is why I was pleased when a giant ironweed (Vernonia gigantea) volunteered in my yard this year. I didn't notice it until it bloomed in the fall.


Ironweed is in the daisy family (Asteraceae), but unlike daisies and sunflowers, ironweed has only disk florets that are loosely arranged into small flower heads. Sunflowers, like many members of the daisy family, have tight flower heads with disk florets in the center and ray florets acting as petals around the edge.  
Native range for giant ironweed (Vernonia gigantea)
Map from USDA.

A late summer bloomer


Giant ironweed blooms in summer into the fall. It attracts many pollinators, particularly butterflies. It's a robust, perennial wildflower, is adaptable and is found in wet to mesic meadows, along forest margins, and next to stream banks. Because of its flexibility,  it's useful in the landscape, but keep in mind that it's not particularly drought tolerant.

It is an excellent addition to a butterfly garden or mixed wildflower meadow in full sun or partial shade. It can grow to five feet or more, so it works best when located in the back of the planting or in the midst of a meadow.


Remove lawn and wildflowers will come


So how did I gain an ironweed volunteer when I've never seen any in the neighborhood? Okay, let's go back to 2012 when my husband and I moved the shed to an opening just behind the garage. We ended up with a weird piece of lawn next to the slope of our raised septic drainfield. In the 2012 photo below, it's where the chairs are and behind the chairs there was some hidden ginger planted on the slope. The raised drainfield is managed as a meadow and it gets cut back once a year or so.

I decided to remove the lawn and the ginger (Curcuma petiolata) to create a sloped wildflower meadow that would not get cut back every year. I started by planting a beautyberry bush (Callicarpa americana) toward the back but with enough space so it would not block access to the top of the drainfield. Then I worked to remove the lawn in several stages. I planted some wildflowers such as some blazing star (Liatris spicata) and spider wort (Tradescantia ohiensis), but many others have volunteered. Over the years, I have pulled out excess Spanish needles (Bidens alba) and pulled back the St. Augustine grass that crawled in over the years, but mostly I've ended up with a nice mix of bunching grasses, goldenrods, coreopsis, and more.

It has been fairly stable until the ironweed appeared. I tried to figure out if there are populations nearby, so after I discovered it, I scouted the roadside ditches and a conservation area about half a mile away, but didn't find any. Then I realized that it was growing near one of those blazing stars had been planted. So my theory is that a seed was in that soil and had been dormant for a while. But I'm happy to have it and even though profiles say that this plant can take over. I look forward to having this surprise native wildflower in my mini-meadow.

The wildflower meadow is where the chairs were located in 2012 after we'd moved the tool shed to this new location. Several years later, we also replaced the wooden stand for the rain barrels In 2018, looking back at the wildflower area to the left of the shed. In the foreground is the exuberant Seminole pumpkin (Cucurbita moschata).

A wildflower area with some planted wildflowers, but mostly filled with volunteers. This same meadow area in a different season..
Ginny Stibolt is a botanist, a native plant enthusiast, and a garden writer with five books and 100s of articles. To purchase her books or read her other articles go to her blog: www.GreenGardeningMatters.com