Weeding out plants with running roots

To oust, evict, remove, eradicate an invasive perennial, groundcover or suckering shrub

It's the same as any weed war.
1) Observe the plant's method of multiplying, then
2) be persistent.

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Here's our method:

To get rid of an unwanted plant that spreads by underground runners, use this method of following the plant outward from its origin. This strategy improves your chances of finding all the root pieces, not only those that have already sent shoots to the surface:

  • Start at the epicenter of the weed plant's area.
  • Use a spade (a rectangular blade shovel, better for severing roots than a pointy digging tool) to slice down through the plant to make an "X".
  • While the spade is in ground for each cut, lean back on the tool's handle to loosen the soil and roots.
  • On the last cut of the X, lean way back on the tool handle. This will raise the cut clod so you can get your hands under it.
  • Now crouch down and grasp that section. Lift it and trace its roots outward.
  • Use a garden fork to go under the clod and loosen further out. Hold the weed's roots in one hand and bounce the soil ahead of you so the dirt falls away and you can follow the roots.
  • As the running roots fan out, separate the clod you've been holding so you can trace each section. When you have followed one whole quadrant of the weed colony, go back to the X and clear the next quadrant.
  • If any weed root snaps, note that spot. Set aside the handful of roots you've been using as "reins" and chase the bit that broke.
  • Where weed roots dive through or under a desirable perennial, lift that other plant, invert its root ball and extract the weed roots from the bottom.
  • Divide the desirable perennial into smaller sections to be certain that you put back only its roots when you replant it.
  • Mulch the weeded area and note your calendar to go out in one week to look for resurgent sprouts.  Pull, break off or apply herbicide to bits that emerge from the smothering layer. Surviving weeds will have expended stored energy to return to the sun. Remove them right away and that weakens them further.
  • Keep checking, loosening and removing survivors each week until the day comes when you find the area is clean. Then, mark your calendar to recheck in two weeks, and then three. Be sure to do a late fall and an early spring check up after waging this war on a plant.

Why to ride herd on survivors

Plant shoots that are forced to work their way horizontally, then grow up through thick darkness and then are broken off as soon as they reach the light will not be able to harness much solar energy. They will not replace as much starch/stored energy as they expended in reaching the sun. So the plant has a net loss and you come closer to a final win.

Weeding under trees

If the presence of woody tree or shrub roots prevents tracing weed roots, or you see that there are deeper levels of running roots you are not able to remove, weed as well as you can with this method. Remove desirable plants to a holding bed or plan to inspect them closely and often. (In a holding bed you will also monitor them closely for weed shoots emerging through their crowns.) Then cover the infested area with overlapped newspaper sections and a thick layer of mulch. Do the regular checking described above to nip survivors as soon as they emerge.

Surviving weeds will be forced to expend even more stored energy to run under the paper to a seam. When you pull, break off or apply herbicide to bits that emerge from the smothering layer, you will be battling a weakened foe.

Last, best advice...

...that is not usually heeded until it's too late, after the beast has moved in and shown its true colors:

Avoid planting invasive plants, as our own garden plants often become our own worst weeds. These words from experts who have been there, make the case:

Some plants are real demons, but are so pretty there's a lot of demand for them. We growers have to carry them. So we sell them with a warning!

- Karen Bovio -


Invasive? Sure, it can be. We told you that. But isn't it otherwise all that you asked for?

- Janet -


When I had a small yard I had to be so careful of what I let loose in there. I tell people if someone offers you a perennial, ask them 'Why?" If they say 'because I have so much of it,' well there you go, there's your warning!

- Deb Hall -