Question of the Week: January 5, 2017
“Neil, I have beds of Asian jasmine and mondograss that are both taller than I would like. Can I trim them down some? How and when?”
I actually have two different answers for those specific plants.
For Asian jasmine, yes, you can trim it down to 5 or 6 inches. That will probably remove all of its leaves, but the stems and bases will sprout out verdant new shoots come spring. You could try doing this with your mower set to its highest setting, but do so in a less-visible part of the bed in case you don’t like the results. Mowers often don’t cut high enough. You remove more than you really intended. You could also try a line trimmer, but it may pull the runners out of the bed.
My own preference, unless I’m mowing jasmine that has been frozen completely back to the ground, is to use a gasoline-powered hedge trimmer. It’s tiring, but it does a nice, even job. You can roll the cut jasmine mat out of the way as you go.
As for the mondograss, that’s a bigger challenge. If it’s been growing for several years it is probably 7 or 8 inches tall. It’s also quite dense. Your lawn mower might have a difficult time cutting through it, plus it will leave it tattered and browned a week after you mow it. But if you wait until mid-February to do it, the “ugly” time will be minimized and the new growth will quickly fill in. Set the mower as high as it will go. Again, start with a less visible spot as your test.
If you do decide that mowing is an option, mow it annually so the next time it won’t be such a shock. That’s what I see commercial landscapers and botanic gardens doing with their mondograss beds. They maintain them at 4 or 5 inches with these mowings. I prefer the untrimmed look in my less formal garden. The only time I’ve ever mowed mine was following a prolonged icy spell several years ago when entire beds turned brown from the damage. That’s one time in 39 years.