Protecting Areas of Princeton Not Yet Infested with Lesser Celandine

Each spring I send out an alert about the spread of a hyper-invasive plant called lesser celandine (also called fig buttercup, or Ficaria verna). Through website posts, letters to the editor, and social media like facebook and nextdoor, I've urged people to take action in their yards to prevent lesser celandine from taking over. The latest effort was a writeup in TapIntoPrinceton. 

Some weeds, like dandelions, proliferate only in lawns and gardens and pose no threat to natural areas. But lesser celandine spreads from lawn to garden to nature preserve, growing in sun or shade, lowland or upland. If left to grow, one plant will ultimately multiply to pave the landscape. Pettoranello Gardens, Marquand Park, Rogers Refuge, Mountain Lakes--these are some of the preserves with rampant infestations. As it displaces native flora, this poisonous plant makes our nature preserves less edible for wildlife.

It can be easy to despair, but the good news is that there are many yards, parks and preserves where lesser celandine is just now starting to invade, and could be easily controlled.

This is what lesser celandine looks like when it first moves in to a new area--a dense mound of leaves with a few flowers in late March and early April.

Westminster Choir College's huge lawn has only five or six of these clumps. It could easily be treated with a little spritz of weed killer (see below for some of the rationale for using herbicide). Five minutes of strategic intervention, and one's work would be done until following up with the same monitoring and treatment next year. 

Here's a sprinkling of just a few plants in Smoyer Park, all in a line, demonstrating how the weed is spread by rainwater that runs along the bottom of this detention basin. Again, this is a very quick job with minimal use of herbicide, with even less needed the following year. 

Here's a big clump next to the school garden at Community Park elementary. If they wanted to be organic about it, they could try covering it with cardboard and thick mulch for two growing seasons and hope the roots die off. Or they could dig it up very carefully and thoroughly, and throw all the plants and associated dirt in the trash.

But that doesn't deal with the clumps of lesser celandine that have spread to the CP lawn nearby. You can't dig up or mulch a lawn, and other alternatives to standard herbicides have not been proven to kill the roots, so you pretty much have to spot spray the lawn with weed killer, or else allow a poisonous plant to take over the very school grounds that a town-wide initiative is seeking to make more edible.

There's a similar dilemma at tiny Barbara Boggs Sigmund Park, where a patch of lesser celandine is spreading across the lawn for lack of strategic intervention. If not treated, that patch will begin to spread downhill, infesting neighbors' yards. 

It's common for one neighbor to let an early invasion expand, unaware of what's going on. This patch is at the back of a property that the owner seldom visits.

Here's another patch spilling under the fence and out towards the street from an infested backyard. This is the only infestation on this particular block, and could be prevented from spreading.

I told the caretaker at Nassau Arms apartment buildings about an early invasion on that property, and he promptly dug it up. Hopefully the diggings went into the trash so that they don't spread elsewhere. We'll have to wait until next year to see how effective it is, but at least there was a quick response. 

What the dramatic and largely hopeless invasions at Pettoranello Gardens and elsewhere can teach us is to treasure and protect those parts of town that can still be spared. To make such protection time- and cost-effective, we must begin by reassessing our blanket condemnation of herbicides as poisons. We don't condemn all medicines as poisons, but instead manage their varied toxicities by applying them selectively and minimizing dose. The same applies to managing a park or one's yard. 

The pandemic dramatically taught us that what each of us does, intentionally or not, affects others. The lesser celandine in one yard or park can easily spread to neighboring areas. This is both humbling and empowering. It tells us that what we do matters beyond the borders of our lives and our yards. Strategic action by the town,  businesses, and residents can stop these infestations while they're still easy to stop.