Mulching eases battle against nutgrass

Getting rid of nutgrass is an almost impossible job for every garden. It requires not only patience but also strategy. Today, I had a new experience in weeding nutgrass, which came as one of many benefits of using mulch - When reading about mulching to eliminate weeds, I doubted that mulch would do much help with nutgrass. What I have just experienced proved this to be true - just not as immediate as killing other kinds of weeds.

The mulched area is in the pathway of my vegetable garden. The constant moisture required when growing vegetables meant the soil under the mulch remain soft. After two-days' rain, the soil was like a sponge mud cake. It required little effort to dig to the depth where most nutgrass' root systems extend.

a "string" of nutgrass

Tools

When digging nutgrass, I like using a narrow, pointed propagating hand trowel. I found it better than a normal weeder as the trowel allows loosening soil around the roots before pulling - which is important because nut grass has thin and fragile roots that separate from the leaves easily and stay in the ground when the soil is compact.

Strategies

Instead of pulling nutgrass one at a time, I often track along the long roots to the next clump, loosen it out and keep tracking carefully without breaking as far as I can. If I am lucky, I will reach the end of the entire system. (The end is often showing a partially developed white shoot.) Without digging the entire system out, it only takes a couple of days for the leaves to come up again, and extend further in their root system.

new shoot on a "nut" that
marks the end of one plant

Benefit from mulching

With digging being a big part of getting nutgrass out of the soil, having soft soil around their roots reduces a lot of hard work. There was a significant colony of nutgrass within the lawn, which was very difficult to kill as the ground was too hard to dig even one nut out.

13 months ago, this area was converted from grass to a shallow no-dig-garden with roughly 10cm of organic layers on top of the original sod. Extra layers of newspaper/cardboard and sugarcane mulch have sometimes been added when necessary, ie. where some grass was still actively growing, or the layers needed a top-up due to heavy traffic and washing-out.
The above-ground result has been little fertiliser (I got so busy with children that I hardly had time to remember to use any fertiliser!) but still having strong and healthy crops growing. Underground, it has become so soft that 90% of the nutgrass could be dug up without loosing their roots. As I dug, I saw nutgrass shoot through half-decomposed newspaper layers and out through the mulch - all soft materials to handle.

soft soil under a patch of
well-mulched nutgrass

As I think back about how mulch was said to have the power of eliminating weeds, I now have to agree with it. The annual weeds I have around certainly die down as soon as mulch is on, thick enough. Nutgrass doesn't die just like that, but in a few months when the soil under the shelter of the mulch becomes so beautifully fluffy, nutgrass then finds no where to hide its roots.