Thursday, June 30, 2022

Weeding Princeton's Fuel Tank Raingarden

When neighbor's complained about the appearance of the fuel tank on Witherspoon Street, the town responded by removing the fueling station's roof, adding a brick facade, and planting the raingarden that had been built to catch and filter runoff from the pavement. 

With the raingarden looking good in its first full year, the intended plants tidily mulched and flourishing, you'd think that it's time to sit back and enjoy nature's beneficence.

But as a gardener who has seen many a raingarden succumb to weeds, I could not help but notice the first signs that a silent, weedy insurrection was in the works. Here is a small patch of mugwort, planning a rhizomatous takeover.

Here's another little, harmless-looking cluster of mugwort next to a lovely St Johnswort shrub. And what's that grasslike plant in the background? That would be nutsedge, easy to pull but also with an underground network of roots that is hard to exhaust. If allowed to grow, it too will spread everywhere. 
The weeds look harmless when there are just a few, but a gardener can extrapolate in the imagination from a little to a lot. I couldn't help myself, and intervened. How many gardens are at such an early stage when thirty minutes of weeding can nip invasion in the bud? Here are horse nettle, mugwort and nutsedge. Feel for the triangular stem on the nutsedge. "Sedges have edges."

Here is white clover, which is benign in a lawn but muddles things in a flower bed.
On the left is a vetch, not crown vetch thankfully, but still worth pulling. 

I pulled pretty much every weed except the nutsedge, whose takeover will hopefully be forestalled by the designated caretaker, if any. Afterwards, the raingarden looked to most eyes exactly like it had a half hour prior. The reward of proactive action is in imagining all the future work that has just been avoided. There will be more work, surely, but much less. 

Maybe someone with designated responsibility would have done the weeding anyway. Nice to think but hard to count on. 

Meanwhile, on the other side of the new fire station, another raingarden was planted at some point. Lots of good stuff growing, but much more intimidating in terms of weeds. It shows what happens when the weeds are allowed to gain a foothold.

The pink is crown vetch, an aggressive plant originally introduced to the U.S. to control roadside erosion. 

And then there's birdsfoot trefoil, originally introduced to the U.S. as nutritious forage for cattle.

And relentless bindweed growing up and over the native swamp milkweed. 

Subduing these three tough customers would take some major work, which makes it all the more amazing to be able to weed the other raingarden and feel like one has the upper hand. 

All of this leads to a point, or two, made before, that regulations require the planting of raingardens in the name of reduced flooding and increased water quality, yet maintenance operations are set up to handle only the simplest of landscapes--turf and trees. Raingardens are a complex community of plants, not a monoculture. They don't respond well to "mow, blow, and go." The person who cares for them needs to be more physician than custodian. They can be planted by people who don't really know the plants, but they need to be cared for by people who do, in a culture that devalues informed maintenance. 

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