Q: We have several large patches of fig buttercup in our backyard. Is there a selective natural spray, or will vinegar work? I want to be eco-friendly, but don’t want it to take over lawns and gardens.

A: No herbicide exists that is specific for lesser celandine (fig buttercup, Ficaria verna), natural/organic or otherwise. Anything used has the potential to damage other plants exposed to the spray. In addition to being largely non-selective, organic pesticides also won’t be systemic, meaning they aren’t going to be absorbed by the plant and moved into roots, where a synthetic systemic herbicide will kill the entire plant.

With tenacious weeds like celandine, you may need several applications of a systemic product to fully eradicate it. Since celandine goes dormant so early in the season (soon after it finishes flowering), some of those follow-up herbicide treatments will have to resume in a second or third year.

Once celandine’s leaves start dying back in preparation for dormancy, they will not be absorbing and transporting herbicide effectively enough, which will make the plant more or less immune to further treatments until it regrows next spring. Dormancy can look a lot like the effects of herbicide damage, so don’t be lulled into a false sense of victory if the plants seem to die after treatment.

Horticultural “vinegar” (acetic acid) is much stronger than household vinegar; being highly caustic, it is not a low-risk pesticide. Contact-type herbicides such as this only “burn off” foliage and do not kill the whole plant. The loss of leaves forces weeds to regrow foliage, using energy stored in the roots and bulbs. This has no different impact on the plant than manually pulling or cutting off its foliage, especially since celandine is adapted to not photosynthesizing for the bulk of the year.

When avoiding herbicide, your only recourse is the more tedious approach of digging up all celandine bulblets and roots and sifting them out of the soil, repeating the process each spring season when you find that any missed pieces have regrown. Since the bulblets move easily with surface-flowing stormwater, if you live downstream from a waterway or runoff from neighboring yards that also have celandine, the plants can keep recolonizing the yard unless that flow can be blocked or diverted. Unfortunately, this may require continued vigilance for new infestations even once you’re successful in eradicating what’s already present.

Q: My lawn seemed to turn more brown this winter than it usually does. Was it due to the cold or snow?

A: Maybe, especially if the snow took a while to melt, but there are other contributing factors that might be responsible. Tall fescue that is under-fertilized (in particular, short on nitrogen) can be more prone to browning during winter dormancy than lawns fertilized once or twice in autumn. While perhaps unappealing, this isn’t necessarily a problem by itself. In comparison, zoysia lawns naturally turn completely brown in winter.

While you don’t want to over-fertilize, following UMD’s recommendations for nitrogen applications over the year can help to keep the grass more aesthetically pleasing in the average winter. Our Lawn Fertilizer Schedule web page provides information for lawn types that comply with Maryland’s lawn fertilizer law, so the risk is kept low for polluting the Chesapeake Bay watershed with unused nutrients.

If a neighbor has a Zoysia lawn, some of that spreading grass may have crept into your yard, which wouldn’t have been as noticeable during the growing season. Nimblewill (Muhlenbergia schreberi) is a warm-season perennial grass that can also colonize cool-season lawns and spread into patches. A native species, it’s traditionally considered to be a lawn weed but might be a more sustainable alternative to consider keeping since it tolerates mowing fairly well. It thrives in less fertile soil, so might coincide with under-nourished turf struggling to remain vigorous.

Any distinct patches of flattened, darker, dead-looking grass might have contracted root rot or another disease if it stayed wet for long periods, such as due to poor drainage and soil compaction. In that case, just clear the site and reseed or re-sod later in spring, and aerating the lawn next autumn right before you overseed should help the turf stay healthier and more able to handle foot traffic and environmental stress.

University of Maryland Extension’s Home and Garden Information Center offers free gardening and pest information at extension.umd.edu/hgic. Click “Ask Extension” to send questions and photos.