There are many weed species found in domestic gardens, but nothing rivals the robust nature of Nutgrass (Cyperus). Cyperus is often a weedy species throughout Australia but most commonly cyperus rotundus, cyperus esculentus & cyperus bifax will be the species you will have to deal with in your residential landscape, depending which climatic zone you are in.
This persistent grass-like plant species has a unique way of ensuring its survival. Hand pulling or your standard glyphosate poisons will not stop it in its tracks. I have seen problem garden bed areas mulched with layers of carpet & lino in an attempt to kill this nocuous weed, only to see it successfully penetrate through the layers & continue to spread.
This grass germinates from a small tuber and via underground stems (rhizomes), creeps its way through the subsoil setting more tubers and establishing upright tufts of leaves to about 10-20cm long. Seed heads occur during Summer & Autumn but usually do not mature to allow further infestation. Because Nutgrass reproduces vegetatively, eradication can be difficult.
Standard herbicides will kill the plant attached to the nut, only to see the nut regerminate. It can be very frustrating but there are specific poisons available at Hardware & Produce Stores. These specific herbicides kill the plant and the attached nut in the ground. It works via the foliage, so the process is still a little arduous with respraying required every 6-10 weeks when additional dormant seeds germinate. As always it is important to adhere to strict health and safety measures when using poisons including not spraying weeds when in flower to reduce the effect on our bee populations.
If using a poison is out of the question, the best approach is to remove a deep section of the soil and replace with fresh weed free soil. This isn’t always a practical approach for large garden areas but essentially all the nuts need to be dealt with and disposed of ensuring your battle with Nutgrass is won once and for all.