Ask Tom: How can I eradicate ground elder from my garden?
Dear Tom,
I have ground elder coming into my garden under a fence from my neighbour. The fence is south-facing on my side so the ground elder is growing towards the sun, and it’s impossible to get rid of. I cannot access my neighbour’s side of the fence as he is elderly and living elsewhere. How can I get rid of the encroaching ground elder?
– Sarah
Dear Sarah,
Sadly, there is no silver bullet here; different garden situations and different philosophies will play a big part in what your preferred method will be.
Aegopodium podagraria, or ground elder, is a perennial weed that will persist year after year with an ever-increasing root system, if left unchecked. It’s worth mentioning that it offers several benefits to wildlife, particularly pollinators, which feed on the flowers. Ground elder is also grown for its medicinal and edible properties, and in the interest of balance, you can even buy a variegated version, if you’re so inclined.
To get on top of this patch of ground elder, I would try to isolate the elder in your border from the source under the fence. You could do this by installing vertical paving slabs (60 x 60cm), although they’re heavy, which makes them problematic for some. There will also be gaps between the slabs, despite your best efforts, so line your side of the slabs with landscape fabric for a thorough seal. To avoid having to handle heavy slabs, dig a trench 60cm deep, then line the trench with landscape fabric to act as a physical barrier, with a small amount protruding above the ground. Once you have isolated your elder, you can then look at treatment.
Firstly, there is the treatment of physical removal. Ground elder will grow constantly through the spring and summer, and it is possible to weaken the plant to the point that it no longer persists. A colleague of mine on local radio uses the mantra “never let it see a Sunday” to constantly weaken the weed, in order to reach the stage that the plant can no longer sustain itself with its root system.
Chemical controls are available, although not necessarily for everyone. Systemic weedkillers that contain glyphosate are absorbed by the leaves and then kill the plant off at the root. Be prepared that it will require several applications as the elder regrows, taking persistence to eradicate this perennial weed.
Consider changing the use of the area; perhaps cover the isolated ground with landscape fabric, top dress with gravel and add a few seasonal containers. Any shoots that appear should be removed as soon as you see them; there may be a few gaps that you’ve missed. You can leave this arrangement in place for a few years, allowing the elder to die off due to the lack of sunlight. In the absence of sunlight, the isolated ground elder should disappear completely, allowing you to be able to grow in the soil again; but leave the soil exposed for a few weeks to ensure that there’s no regrowth before you replant.
Alternatively, once you have isolated your border, line it with landscape fabric and then build a raised bed on top of the fabric. It is important to ensure that the soil in your raised bed is separated by a physical barrier at the base, allowing drainage, to prevent contamination from the elder. The south-facing aspect that you describe would be perfect for growing a wide range of plants, including fruit and veg.
With many pests and weeds in the garden, the secret to success is to be more persistent than your adversary.
