Clay soil and ground elder - a good combination?

Ground elder... The perennial weed that (along with bindweed and horsetail - both of which are very much at home in the garden, thank you), when he was asked on BBC Radio 4's Gardener's Question Time how to deal with them, prompted Bob Flowerdew to advise, "Move house!"

That option not viable, for the past three weeks, I 've been bottom up in a flower bed, grubbing up the tall green stalks (which had reached a rather unexpected 24 inches high) and long white stringy roots.  It's given me plenty of time to consider the extraordinary properties of the clay soil in which they are buried and the relationship between them (but more of that below).

First, clay. As I slowly advanced to the back of the border, removing the leaf cover and without heavenly precipitation, the soil dried out to something resembling hardcore - all hard, dry, misshapen lumps. Impossible to plant in, miserable to weed. I had to lean on the handfork to penetrate the ground.

Two days' watering, fifteen minutes at a time, and on the third day it had magically restored itself to its best condition - moist, easily broken up, easy to handle. Very easy to weed.

Now, after severe drenching (and I'm sorry, all this rain is obviously because I wielded a hose), it's thick and sticky, clinging like cake mixture to the gloves and hiding the roots in its glutinous grasp. Weedable, but not enjoyable.

Now, ground elder... My theory is that it hugs the heavy ground. It mats itself most in the areas where the soil's been left to its clayey ways. Those areas where I've piled on compost do see ground elder creeping in, but it seems not to advance with gusto and is much easier to keep on top of.

Of course, it could be that the improved areas are more visible and easier to weed anyway, so I'm removing a lot more than I think, but my theory is that it actually enjoys breaking up heavy soil. In New Age parlance, the presence of ground elder in clay is the soil healing itself, the roots strong enough to run through it, breaking it up, creating passages for air and water.

Too fanciful? Whether this is true or not, the remedy to this infestation (because we all know the ground elder will return. Oh, yes) is still to improve the soil. More organic matter, aerating the tiny clay particles, will keep it open in wet weather and less prone to imitating concrete in dry.

I'll be spreading a compost mulch and leaving it. Ground elder is often given as a reason not to adopt No-Dig gardening. But, as I surely know after the last few weeks, its roots mostly run no more than an inch or two below the soil's surface. The worms will draw in the mulch, creating a better soil, and the roots just lift out. It's actually quite fun. You can't beat the satisfaction of removing a root 24 inches long (it happens).

However, my theory (and I'd love to hear what others think of this) is that improved soil will also discourage ground elder because the weed will no longer be immersed in the heavy clay that it so obviously relishes.

That's my theory. You may call it wishful thinking.

March 2015: And here's an update on how I was getting on a couple of years later.

Comments

[kininvie]

Interesting - I have exactly the same combination of heavy wet clay and ground elder. But I fear your remedy of improving the soil will only encourage it - it will move its roots up into the nice stuff and just keep going. If you can't use weedkiller, I've found that burning every shoot and leaf as they emerge, with a weed wand does a lot to discourage it. But you have to burn every week,as a minimum.

[Helen]

Hi, Kininvie I hear what you're saying, and improving the soil seems counter-intuitive. But I'm banking on the idea that once the soil's in good condition, the roots lift out much more easily and can be kept in check. Charles Dowding, the no-dig expert, says this, so I'll give it a go. Hate weedkiller, but I did try Round-up on the ground elder once. It merely thumbed its nose at me and laughed. Hadn't thought of burning, though - wouldn't have to bend down so much to do that, which would be good.