How to kill chameleon plant — and encourage lesser celandine

DEAR JESSICA: I planted what I call camouflage, or chameleon plant. It started to take over, so I pulled it all out. Now, a decade later, it is still “crashing the party.” It is in densely planted areas with sedum and creeping phlox, so I can’t spray, nor can I dig deep enough to get out the entire root. Can I put Roundup on a cotton swab and apply it to the leaves? — Diana Corrao, Huntington Station

DEAR DIANA: Houttuynia “chameleon” is a true chameleon: It’s a devil masquerading as a gorgeous plant. I completely understand how you fell under its spell, and I can picture you strolling innocently through the nursery and stopping dead in your tracks when you saw its deep purple-edged green leaves, scooping it up without a second thought.

After planting, it spread slowly, providing a nice, well-behaved ground cover. You slept peacefully. But around year three or four, it lost its mind. Underground runners spread sideways and sprouted in every direction, and you started spotting baby plant “volunteers” 5 feet away. Maybe they invaded the lawn. You pulled them up, but others replaced them.

Unless you dig out every last piece of root — and sift the remaining soil to ensure you don’t inadvertently leave behind a broken bit, you will lose this war.

Although I reserve the use of chemicals for extreme circumstances, make no mistake: This plant is virtually impossible to eradicate in the conditions you have without them.

As you know, Roundup’s active ingredient, glyphosate, will destroy everything it touches. To protect the plant’s bedmates — your phlox and sedum — and prevent them from becoming collateral damage, you’ll need to very precisely target the invader.

Use a small foam paint brush to apply the weed killer to leaves, taking care not to allow the product to contact other plants. The planticide likely will require several attempts, and may need to be followed up with some hand-digging.

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Alternatively, depending on how densely planted the area is, you might consider temporarily moving the desired plants to another bed and applying weed killer to the entire area, carefully adhering to package instructions, then returning the plants to their homes at the end of the season. If you decide to go that route, be very careful not to move any chameleon roots with them. Good luck!

DEAR JESSICA: I read your April 16 column on lesser celandine with great interest. I consider them flowers and have transferred them from the wild to my property over the past 20-plus years. Is there anything I can do to promote their growth? I have noticed that some of the oldest patches no longer have yellow flowers. In the newer areas where they have spread, the flowers are a vivid yellow. I have not mowed as of yet and will not until the yellow blooms are gone. What can I do to get the older plants to bloom again? — Elliot Zolin, Roslyn Heights

DEAR ELLIOT: Although considered a weed by some, many gardeners welcome the golden waves of spring color that lesser celandine brings to lawns and beds in March and April. Bright yellow buttercup flowers stand 2 to 6 inches above glossy green foliage during daylight, and close up for the night. The ephemeral perennial ground cover grows quickly, blooms and goes dormant during a two-month period, after which it disappears underground without a trace until next spring, when its roots send up new plants.

You seem to be familiar with them, but, still, I do need to warn you that lesser celandine is invasive and may eventually become a nuisance, or worse, as they will spread far and wide.

To encourage blooming, apply a water-soluble fertilizer that's high in phosphorus every two weeks during the growing season, and ensure plants get ample sunlight and water.