How To Kill Tuberous Rhizome Weeds

Tuberous rhizome weeds have thick, exploratory roots capable of sprouting new growth. Each time you pull up one plant, a new plant could still appear from any roots left in the ground. This makes them especially tedious to control in the lawn or garden. You can successfully kill tuberous rhizome weeds but only with a long-term approach.

You'll know you're dealing with tuberous rhizome weeds if you dig them up by the roots and see potatolike bulges (tubers) growing from rhizomes (modified underground stems).

Nut sedges (​Cyperus​ spp.) represent a particularly hard-to-kill weed. One fresh sprout can produce new rhizomes within six weeks, and over 6,000 tuberous rhizomes have been traced back to a single tuber, called a nutlet. Florida betony (​Stachys floridana​) is another example of a tuberous rhizome weed often encountered in lawns, gardens and fields around the United States.

Broadleaf herbicides do not always work on tuberous rhizome weeds because of their extensive and expansive underground network of tubers and rhizomes. Broadleaf herbicides often accidentally kill desired plants instead. Given the environmental and health impact of herbicides, it's best to avoid this approach.

If you're dealing with a relatively small infestation of tuberous rhizome weeds, it's best to dig them up by hand. Do not take an aggressive approach like tilling or otherwise hacking into the dirt because this can divide the roots. Each section of root has the potential to sprout a fresh weed, so you don't want to leave anything behind.

Use a hand tool designed to remove weeds to uproot the main plant. Then use a hand rake to move dirt away from the lateral rhizomes until they're revealed and can be removed. Alternatively, you can shovel dirt on top of a soil sifter. Push the dirt around on the screen until all the soil crumbles through the holes, leaving the roots behind.

Expect to repeat this procedure throughout the growing season for several years in a row to completely eradicate these weeds. Even if you don't have time to dig up a fresh sprout, keep an eye on it and cut the stem before it has a chance to flower or go to seed. Put these weeds directly into a yard waste container; do not compost them or otherwise allow them to linger in a pile in your yard.

The best way to battle a large infestation of tuberous rhizome weeds involves starving them of sunlight. The plants have a significant amount of food stored in their roots and tubers, so they can survive for some time without sunlight. Eventually, however, they will die.

For best results, do not use regular landscape fabric. Instead, use a heavy-duty product called bamboo barrier or rhizome barrier. Made of polyethylene, this barrier is much stronger than typical landscape fabric. Place it anywhere you know these weeds currently exist as well as anywhere you don't want these weeds to appear.