Remove — by hand or herbicide — invasive lesser celandine that can take over lawns

“How did the Sure Power herbicide you referenced in a column last year work to control lesser celandine in your lawn?”

— Samantha Jefferson, Highland Park

Lesser celandine (Ficaria verna) is a very invasive spring ephemeral perennial plant that has become more prevalent in gardens and lawns.

Leaves begin to emerge before flowering in very early spring, so look for it before other plants have started to grow.

Because lesser celandine emerges well before native and ornamental species, it has a developmental advantage that allows it to establish and overtake areas.

It forms large, dense patches in your garden, so watch for it and eradicate even very small clumps as you see them.

You can also find it growing in the crowns of perennials and bases of shrubs.

Plants consist of a basal rosette of succulent, dark green, shiny, kidney- to heart-shaped leaves that creep across lawns and beds.

The flowers are easy to recognize with eight (typical) to 12 bright yellow petals arranged symmetrically around a slightly darker center that rise above the leaves on single stalks. Lesser celandine can be easily confused with marsh marigold (Caltha palustris) — a native plant found in wetland habitats and in some home gardens with moist areas.

Some of the lesser celandine plants in my home garden are starting to flower now. The foliage begins to die back after flowering and will mostly disappear by June or earlier if temperatures are consistently warm.

Lesser celandine spreads primarily by vegetative means through prolific tubers and bulblets, each of which can grow into a new plant once separated from the parent plant. The tubers may be unearthed and scattered by the digging activities of animals, as well as weeding, and spread to new sites during flood events.

For small infestations in garden beds, lesser celandine may be dug up using a hand trowel or shovel. It is very important to remove all bulblets and tubers, since each one left in the ground can grow into a new plant. For example, rototilling a bed simply propagates this plant, allowing small plants to come back the following year.

Be persistent in removing the weed. I have had success in eliminating it from vegetable garden beds by weeding it out year after year. All parts of the plant must be bagged and disposed of properly. Do not put it in a compost pile.

While manual removal methods are possible for small infestations, using a systemic herbicide is more effective for small and large growth because it kills the entire plant — including the roots — and minimizes soil disturbance. Expect to treat plants two to three times each year over a period of years to get this plant under control if it is already well established in your garden.

It’s important to apply an herbicide just as the weed begins growing for the best control and to minimize damage to adjacent desirable plants. Start applications prior to flowering and up until about 50% of the plants are in flower and then stop.

I usually make two to four applications in my garden beds as more plants continue to sprout over time.

It’s getting to be late now for optimum results but it is still worth trying. Applications can be made early in the season when the temperature is 40 degrees Fahrenheit or above, and no rain is anticipated for 12 hours. It is best to use a spreader sticker with the herbicide, since the leaves of lesser celandine have a waxy covering that repels water.

Glyphosate herbicide is systemic, with the active ingredient absorbed by the plant and eventually killing it. Re-treatment over a few years will probably be necessary. Because glyphosate is a nonspecific spray, it should be applied so that it contacts only lesser celandine and does not drift onto desirable plants such as turf grass or perennials.

Over the last two years, I have used the product Sure Power for the lesser celandine growing in my lawn.

Sure Power seemed to knock it back more dramatically than other products. The large stand of lesser celandine returned this spring, though in slightly smaller numbers with generally smaller and less vigorous foliage.

I sprayed twice again this spring and had good timing on the first application with the foliage curling, stopping growth and turning brown. Plants that I missed on the first application and sprayed about a week later are less affected by the spray.

I plan to continue treating with Sure Power in future years and have opted not to use the nonselective herbicide glyphosate to treat the lawn. I doubt that it can be eradicated with one season of spray and do not want to reseed my lawn multiple times. It’s important to read the label on whichever herbicide you decide to use to make sure you are using it properly and safely.

For more plant advice, contact the Plant Information Service at the Chicago Botanic Garden at plantinfo@chicagobotanic.org. Tim Johnson is senior director of horticulture at the Chicago Botanic Garden.