Smilax ID and Control

It has wicked thorns, it laughs at herbicides and it always seems to come back, no matter how much you pull it out of your shrubs each spring. Nobody smiles when smilax vine appears

The pest is smilax (deer thorn, catbrier), one of the toughest perennial vines with which a gardener has to contend. The thorny vine with waxy, heart-shaped leaves wends its way through azaleas, English laurel and perennial flower beds with impunity. Smilax has berrylike fruit that birds enjoy — but this vine is no joy to control.

As the smilax begins to grow from seed, it sends up a single shoot and produces an underground bulb. As the plant matures, a large cluster of bulbs is created. Only a few shoots will arise from the root mass; the majority of the bulbs lie dormant. If you kill one shoot, that bulb may die, but adjacent bulbs may send up shoots within a few days.

Greg MacDonald, Extension weed specialist, says control of smilax should focus on early detection and control before more bulbs are formed. If you find this noxious vine, better to dig it up rather than chopping it down.

Try to get all the bulbs out of the ground. The only other option is frequent sprays of a weedkiller like Roundup or Brush-B-Gon. Eventually the root mass will be depleted, but the process may take months, even years.

Q: I have an evil force at work under my yard. There is a network of sticker vines which grow along a seemingly endless root system. I went on a rampage several years ago and tried to dig up the root system and ended up digging up the better part of my yard. Now the sticker vines seem to have mutated and are back in full force. I’m ready to try just about anything short of a full out nuclear attack! Please help me KILL THE EVIL ALIEN STICKER VINES!!!

A: I hear your frustration! Tough vines like wisteria, English ivy and kudzu are a headache to eradicate. My guess is that you have smilax, also called green briar, deer thorn and “that *^!!( %* !! sticker vine”. Smilax has a deep tap root that allows it to re-sprout no matter how many times you chop it down. Weed chemicals don’t easily penetrate its glossy leaves. Short of calling in a bulldozer, how can you control the vine or get an effective herbicide down to the root system?

Here’s an idea to try one warm spring day: Use the systemic herbicide Roundup ™ to make three gallons of diluted solution in a five gallon plastic bucket. Find the sticker vines in your yard that have grown several feet long. Pull them off the ground and drape as much vine as you can into the bucket. Let each vine soak in the solution for fifteen minutes or so. In this way you’ll let the vine soak up the maximum amount of poison.

Once all the vines have soaked, you’ll need to dispose of the surplus pesticide. Roundup has a good environmental safety record and is inactivated when it touches the soil. Dig a shallow hole in a spot where there are no plants growing nearby and pour the leftover chemical there. You could also use it to spray on other weeds if you can strain the trash out of the solution.

NOTE: I have gotten good control spraying Roundup twice, at two month intervals, on a smilax thicket on my mother’s property.

neighbor holding long smilax root