Friday, July 18, 2025

Summer Roadside Weeds in the Midwest

Many roadside weeds common in the midwest have yet to make it in any numbers to eastern locales like Princeton, NJ. Unless differences in climate or soil are limiting these nonnative weeds' rampancy in the east, a trip to the midwest can feel like prelude for what eastern roadsides could look like decades from now. Even if they can't compete with tough customers in NJ like the nonnative mugwort and Japanese knotweed, their behavior along midwestern roadsides shows what those first few popping up in Princeton could turn into over time. 

Here's a display of roadside weeds collected on the hood of my rental car at a rest stop. This was in Ohio, though the same roadside weeds are found in Wisconsin, Michigan, and likely other midwestern states as well. The row of blue flowers on the left are chicory. The delicate white disk of Queen Anne's lace--the wild version of the carrots we eat--is in the upper right. Yellow sweet clover--there's also a white version--is in the lower right, and the pink flower in the middle is spotted knapweed.

All of these, which seem so modest when they first show up, can ultimately form dense stands along roadsides in the midwest, as can other non-natives like the tall, dramatically shaped teasel

and the Canada thistle whose tops become thick with fluffy seeds this time of year (see photo). 

Less common are the tall yellow spires of wooly mullein, which in most patches appear less exclusionary in their growth habit.

One super-invasive found along roadsides in both the east and the midwest is Phragmitis--the towering "common reed" with large plumes on top that forms dense stands in ditches, displacing the native cattails. Driving on I-94 around Ann Arbor, MI, I noticed dead stands of Phragmitis--evidence they have been sprayed to save the patches of cattails the Phrag was invading. That's the first evidence I've ever seen of selective use of herbicide for restorative purposes along a freeway. 

Another nonnative I keep an eye out for, both in Princeton and the midwest, is birdsfoot trefoil. Mostly it appears as small patches of yellow in a lawn or along a roadside, but I found one instance in Ohio that shows its potential to spread and dominate, coating a large area, much like crown vetch has done where it was extensively planted for erosion control along freeways in Pennsylvania. 

What grows along roadsides can spread to grasslands being actively managed for native species. We were pulling spotted knapweed out of prairies in Ann Arbor in the 1980s. I once witnessed birdsfoot trefoil being assiduously pulled before it could spread across a prairie packed with native diversity at Kishwauketoe--a nature preserve in my home town in Wisconsin. The botanist there knew that a little can quickly turn into a lot, so better to catch those weeds early. 

The vast majority of drivers are oblivious to these roadside dramas, where a pretty flower can become too much of a good thing. For me, a drive through Ohio provides useful guidance for deciding what to weed out of a meadow in Princeton. 

Related post: Stiltgrass Reaches Michigan -- While midwestern weeds are moving east, eastern uber-invasives like lesser celandine and stiltgrass are just starting to pop up in Michigan.

Thursday, July 03, 2025

Fuel Tank Raingarden, Lost to Weeds, Receives Reboot

Well, it finally happened. After five years of letting weeds get the upper hand, a maintenance crew declared defeat and tore most everything out of the raingarden next to the town fuel tank on Witherspoon Street. 

The trajectory from first year splendor to decline and fall (see links below) is a familiar one. For thirty years, in three different towns and cities, I've been watching how complex landscape plantings prosper or decline. By complex, I mean any planting containing more than three intended species.

One could talk about how maintenance is undervalued in our society. People talk about planting a tree, but few talk about the followup care--the watering and weeding that determine whether that tree survives. Good maintenance is invisible. People notice when things go wrong, not when things are kept right. This is true whether it be a well maintained raingarden or a well-run government. Both go underappreciated, at their peril. 

And we could talk about pervasive plant blindness--the scarcity of people who can distinguish one plant from another. We expect medical staff to be knowledgeable about the human body and its afflictions. A raingarden also requires expertise to keep it healthy. To weed with confidence, the landscape crew needs to be able to identify not only the intended plants but also the myriad weeds that invariably move in.

Here, in the foreground of this photo, you can see the main culprit. Though there are many other weeds, mugwort is the most aggressive non-native weed in a raingarden. Unchecked, it spreads quickly, soon leading to a sense of despair. 

Also working against success is the typical scheduling used in a maintenance department. What if the two visits per year coincide with dry conditions? Weeding is best done when the ground has been softened by rain, and before the weeds have a chance to set seed. For a raingarden to be low-maintenance, intervention needs to be strategic and well-timed. That won't happen with a rigid schedule. 

And sometimes I wonder, in this era of toxic masculinity when empathy is criticized as a weakness, whether a raingarden for some is too feminine, too complex or too hippie-like, and so ultimately yields to the masculine need to dominate with a mowing machine rather than nurture with a trowel. For whatever reason, the simplified, close-groomed look of a lawn tends to win out.

Turns out, though, that the fuel tank raingarden wasn't converted to turf out of frustration, but was instead replanted, probably at considerable cost. This suggests a commitment to maintaining the raingarden as a garden.

And yet, at the bottom of this photo, you can see the mugwort has not completely gone away. 

Like our own immune systems, constantly quelling potential riots of pathogens lurking inside our bodies, a raingarden needs someone skilled in quelling the quiet riot of weeds lurking in the soil. With vigilance and timely intervention, the job gets easier and easier and the raingarden will flourish as originally intended. A skilled caretaker would spot these weeds and pull them out before they have a chance to gain momentum.




 
Just for comparison and to show what's possible, here is a thriving raingarden in Hopewell, in front of the Peasant Grill. It remains a low-maintenance, attractive planting year after year, surely because someone with knowledge acts quickly to pull weeds before they can get established. This is the informed, timely intervention we expect for ourselves in good medical care.

But even in that well-tended planting in Hopewell, a few pesky mugwort are ready to become many if there's no skilled caretaker to spot them quickly and pull them out. Sustaining peace, beauty, and harmony requires ongoing vigilance.

Another example is the wet meadow I take care of at Smoyer Park--essentially a detention basin planted with native wildflowers and grasses. It is fed by runoff from the main parking lot.



Below are annual posts that have tracked the fate of the fuel tank raingarden, from bare ground to freshly planted splendor, followed by increasingly weedy chaos and this year's reboot. 

2020 Princeton Fuel Tank Raingarden Wannabe

2021 Princeton Finally Plants its Fuel Tank Raingarden

2022 Weeding Princeton's Fuel Tank Raingarden

2023 Fuel Tank Raingarden Threatened by Lack of Early Intervention

2024 Fuel Tank Raingarden Losing Out to Weeds


A Great Video about Pollinators on Mountain Mint

Some wildflowers are much better at attracting pollinators than others. The two champions in my book are clustered mountain mint and boneset. Back in 2008, I started documenting the many kinds of insects and other creatures drawn to the boneset growing in my backyard. Little did I know that an entomologist friend I hadn't seen since Ann Arbor college days, David Cappaert, had been inspired to do the same, 200 miles away, with the mountain mint growing in a Hartford, CT schoolyard. 

Dave had the advantage of 1) being an excellent photographer and 2) actually knowing the creatures' names. He created a remarkable video entitled "Mountain mint, one day in August," in which he documents 52 species he found on one stand of mountain mint. For its first 8 minutes, the video is a parade of colorful creatures with colorful names like bee wolf, wedge shaped beetle, stinkbug, ambush bug, jumping spider, freeloader fly, and orb weaver. 

Then, at 8:20 in the video, Dave begins describing the many interrelationships between the pollinators and their predators and parasites--a wonderfully complex food web, all "fueled by the nectar of the mountain mint." Check it out, and if you don't have any mountain mint growing in your yard, come to the Botanical Art Garden at Herrontown Woods, where in early July it's just starting to bloom. 


 

Note: We also have another kind of mountain mint growing in the Botanical Art Garden: what I've been calling narrow-leaved mountain mint (Pycnanthem tenuifolium), which is the more common species found growing naturally around Princeton, but clustered mountain mint (Pycnanthemum muticum) is the champ when it comes to pollinators. Being a mint, it also spreads quickly underground, so be careful where you plant it.