Eradicating lesser celandine and bentgrass, and protecting arborvitaes
Lesser celandine, commonly called fig buttercup, can seem like an invasive weed. But if you wait it out, it'll disappear without a trace in six to eight weeks. Credit: Irene Rocco
DEAR JESSICA: My husband thinks these are weeds; I say they are flowers. I planted them before I had a garden journal, however, so I don’t remember what they are called. They are quite invasive, spreading onto my lawn and at the base of my hydrangea plant.
Please help us settle this disagreement and tell us how to stop them from taking over.
— Irene Rocco,
East Northport
DEAR IRENE: Technically, you’re both right: a “weed” is defined as a plant growing where it isn’t wanted. So if your husband doesn’t want it, to him, it’s a weed. Weeds, too, typically are invasive, growing wild and spreading without boundaries, which this plant appears to be doing. If you planted it deliberately, and want it to color your lawn in spring, then it’s not a weed; it’s ground cover and a pretty harbinger of the season.
This particular plant — lesser celandine (Ficaria verna), also known as fig buttercup, is an ephemeral perennial, which means it pokes out of the ground, grows quickly, blooms and goes dormant, all over the course of just six to eight weeks, after which it disappears underground without a trace until next spring.
There are ways to eradicate it, although its presence among grass means you’ll have to protect your lawn while doing so, and that rules out the use of nonselective weed killers, which I don’t typically like to recommend anyway, unless there is no other choice.
You can treat it with an iron-based broadleaf herbicide, such as Fiesta, which is actually specifically labeled for use on this plant, among others. This is best done very early in the season, before it flowers, as the plant is most susceptible at that time. You also can dig it out from under your hydrangeas and other plants, taking care to lift its long tap root out of the ground without leaving broken bits behind. But neither method is foolproof.
Or, you could just wait it out; it’ll be gone in a few weeks. That’s what I would do.
DEAR JESSICA: What is the best way to tie up my 15 arborvitaes, which are about 20 feet tall and are falling over from bad weather? If I use two-by-fours, the wood would not last too long. If I use pipe, it gets expensive. Also does tying a rope around the trunk hurt the shrub? Is there any special way of taking care of this?
— Joseph Ferraro,Dix Hills
DEAR JOSEPH: Arborvitaes are among the most popular evergreen landscape trees and shrubs on Long Island, commonly used on their own as screening, hedgerows or to soften fence lines. Unfortunately, many varieties, such as ‘Emerald Green’ and ‘Green Giant,’ don’t hold up very well when their branches are weighed down by snow or ice, becoming misshapen — sometimes permanently — or worse, cracking and breaking from the stress.
To protect trees from such damage, they can be wrapped in autumn with burlap, landscape fabric or even rope or bungee cords to keep branches upright and together.
Just don’t leave winter protection on too long: remove rope or wrapping as soon as the danger of snow has passed in early spring.
DEAR JESSICA: Several years ago, our lawn looked like a battlefield, and I had a nursery treat numerous areas of bentgrass with Roundup. It was aerated and reseeded with Kentucky blue and fescue. The affected areas are back with a vengeance. Short of repeating the process, is it possible to seed with a seed that will choke out the bentgrass? When I maintained our lawn, we never had this problem. We’ve been using a lawn service for the past 15 years and wonder if they infected our lawn.
— Frank Fuoco,Commack
DEAR FRANK: Bentgrass isn’t recommended for planting in mixed-grass lawns because it requires closer mowing than other varieties. Combined with bluegrass and fescue, it will stick out like a sore thumb and make your suburban patch look like the battlefield you described.
It’s entirely possible that seeds hitched a ride to your property on your landscaper’s mower, as you suspected, and now that it’s made itself at home, I can understand why it bothers you.
Unfortunately, there is no one grass seed variety that will outcompete bentgrass, but if left alone, over time, the bentgrass may outcompete the blue and fescue in your lawn.
If you’re determined to eradicate it, your only real option is to apply one of two herbicides. Spot treat each bentgrass patch with Roundup, extending the application a few inches beyond each for good measure. This must be done twice; you’ll know when the second is needed. Avoid treating during periods of extreme heat or drought.
Another product you can use is called Tenacity, which will not harm your other grass, but it isn’t as fast-working. Apply three times, two weeks apart, beginning in early July. Bentgrass will die and turn white shortly after each treatment.
Regardless of the product you choose, you should core aerate when the regimen is completed, as your landscaper has done, and then reseed over the whole lawn with your chosen grass blend, watering deeply immediately afterward. To ensure complete coverage, seed once a week and water lightly daily until the new grass reaches a mowable height.
