see this: R. ficaria

Keep in mind that the World Health Organization has labeled the glyphosate products as carcinogens.

kimmq is kimmsr

If you have large patches of nothing but unwanted plants, smothering is the easiest way, no chems required.

While I appreciate those concerned with keeping me organic, this particular problem cannot be solved in this way. I cannot smother ficaria (I tried all last summer-3 months), it spreads by tubers underneath the ground-and pops up again. I also tried hand pulling and created 1000 more plants, because the bulbs are the size of a pea, and you usually can't find them all in the soil. I have 1/2 acre and 1/3 of it is being overrun with this invasive plant. I am looking for advice from people who might have used these two herbicides in the past on this particular weed. Sorry to disappoint, but this is the best solution that I have found after researching this extensively online.

floral-smothering early winter makes sense for timing, but it was my thought that this would just kill off the present leaves, but would not effect the bulbs and tubers. Once I remove the cardboard or plastic won't ranunculus ficaria just reemerge from the bulbs/tubers once light is available again? Can you smother a bulb/tuber? You are right about the environment. This weed was established in a wet, low lying area where nothing was planted or mulched-no grass. I am attempting to establish grass there now, but my prep-tilling + hand weeding-caused a bigger problem. I am battling Gremlins!

I've never actually tried smothering but my thinking was that in Spring they would attempt to grow leaves and exhaust the tubers trying. You might need to keep it covered into the second year too. Just a thought. I just curse mine and wait for them to go dormant.

That is a thought, but not sure I can do that in the lawn. Have a feeling I will join you in the cursing.

Please see the link I posted above.
With herbicides, the timing is critical. Then, because of the tubers, this is NOT a once-and-done sort of thing.
You must be persistent.
You must be active for several years.
If you stop for just one season, the plants will regain all their losses and set you back to square one.
This is your new hobby.

Be persistent and you can win!

Thanks jean-I had read that link before -which gave me the idea for rodeo, but it is expensive-which is why I wondered if others had used roundup with success. I realize I will have to do this for 3 seasons or more-yuck. But if I can be done with it-it will be worth it. Thanks for all the advice.

Rodeo is like Round-up minus additives that they say harm amphibians. They both have glyphosate as the plant killer chemical. So Rodeo is made for wetlands. I believe through my research that they both will affect the lesser celandine in the same way.