How to Get Rid of Invasive Bishop’s Weed (Goutweed)

Bishop’s weed also known as goutweed or Aegopodium podagraria is an invasive perennial plant that can quickly take over gardens and landscapes. Originally introduced as an ornamental plant, bishop’s weed has now naturalized across much of North America and is considered a noxious weed in many areas. With its aggressive growing habits and difficult-to-remove root system, getting rid of bishop’s weed can be a challenge for gardeners.

What Makes Bishop’s Weed Such a Problem

There are a few key characteristics of bishop’s weed that make it highly invasive and hard to control:

• Fast spreading rhizomes – The plant spreads rapidly via underground rhizomes. These white, segmented rhizomes creep horizontally through the soil, putting up new shoots and roots as they go Just a small piece of rhizome left in the soil can generate a whole new infestation.

• Rapid growth – Bishop’s weed grows quickly, spreading out to form dense patches that crowd and shade out other plants It can spread at a rate of about 1 foot per year

• Difficult to remove – The extensive underground rhizome system makes it nearly impossible to fully remove bishop’s weed by digging it out. Any remnants left behind will resprout.

• Shade tolerance – Unlike many weeds, bishop’s weed is quite shade tolerant. It flourishes not just in full sun but also in partial shade beneath trees and shrubs.

• Few insect or disease problems – With no native insect pests or diseases in North America to keep it in check, bishop’s weed grows unimpeded.

Identifying Bishop’s Weed

Being able to accurately identify bishop’s weed is the first step in controlling and removing it. Here are some key identification features:

• Grows 1-3 feet tall on upright, hollow stems.

• Leaves are triangular shaped with coarsely toothed edges. They are 2-5 inches wide.

• Produces clusters of small white flowers in early summer. Flowers have 5 petals.

• Spreads rapidly to form large, dense patches.

• Leaves and stems emit an unpleasant odor when crushed.

If an unknown plant in your yard seems to match this description and is spreading aggressively, chances are good it is bishop’s weed.

How to Get Rid of Bishop’s Weed Organically

For gardeners who want to avoid using herbicides, controlling bishop’s weed organically is possible but requires persistence. Here are some of the most effective organic methods:

• Repeated hand-pulling – Grasping plants at the base and gently pulling to remove as much of the roots as possible must be done vigilantly to weaken the plant over time. Any roots left behind will resprout.

• Smothering – Covering areas of growth with mulch, cardboard, or landscape fabric will block light and can kill bishop’s weed over one or more seasons. Edging around the areas helps contain spread.

• Solarization – Solarization uses heat from the sun under plastic sheets to weaken and kill plants and seeds in the soil. Covers must remain in place for at least a full growing season.

• Digging – For small areas, digging out bishop’s weed completely including all roots and rhizomes can provide control. Perennials should be lifted and isolated until the area is clear.

• Competition – Planting species that aggressively fill space and shade the ground may help compete with bishop’s weed over time. Options include ivy, vinca minor, or native groundcovers.

While these organic options all require substantial effort, they can be successful over time if implemented properly and consistently. Preventing any growth and flowering is key to depleting bishop’s weed’s reserves.

Using Herbicides on Bishop’s Weed

For large infestations, most experts recommend using glyphosate (Roundup) or other systemic herbicides for the most effective control:

• Glyphosate is a non-selective systemic herbicide that translocates throughout the entire plant when applied to the leaves. This kills the entire plant including the roots and rhizomes.

• Glyphosate products should be applied when bishop’s weed is actively growing in early summer. At least 2-3 applications per season may be needed.

• Adding a dye or colorant helps identify covered plants and avoid drift onto neighboring plants.

• Glyphosate has no soil residual so planting or seeding can be done soon after treatment.

Always carefully follow label directions when using any herbicide product. While glyphosate will damage or kill any plants that come in contact with the spray, it can provide necessary control when dealing with a major bishop’s weed infestation.

Preventing Bishop’s Weed from Returning

Getting rid of existing bishop’s weed is only half the battle. Preventing it from taking hold again in the future takes vigilance:

• Inspect gardens routinely, especially edges, and immediately remove any young bishop’s weed plants. This prevents rhizome establishment.

• Clean tools, shoes, and tires that have been used in infested areas to prevent spreading rhizomes.

• When bringing in new plants, inspect root balls and avoid introducing any weeds. Quarantine new plants outdoors in pots for a few months to watch for hitchhikers.

• Maintain healthy garden soil and planted areas. Bishop’s weed opportunistically invades open, disturbed soil.

• Solarize soil in fall to killseeds and rhizomes in areas prone to bishop’s weed.

While challenging to control, bishop’s weed can be successfully removed from landscapes through persistence. Paying close attention to preventing new introductions is key to keeping it from retaking root. A vigilant gardener can reclaim their space and deny this aggressive invader any footholds.