I have been weeding since I was a small child, even if sometimes the plants I pulled out weren't weeds! This has been a bit of an obsession. Lawn is particularly difficult to do weeding. For a while I have been weeding lawn by hand, which was a lot of work, even with a weeding tool. Unfortunately for some of the species of weed this was unavoidable, like this dark green grass growing like matchsticks out of the lawn:
The above grass was time consuming to remove, however fortunately it took up a relatively small amount of lawn. In fact, it's almost wholly shown there and was completely removed by hand since. It involved loosening the area with a pitch fork then digging right into the lawn with my bare fingers and pulling out by the root. Some grew back from the neighbours and so will need to be done again.
A lot of bindii used to grow in this particular lawn - no more. It was pretty much eliminated using selective weed killers from Bunnings.
The wintergrass is possible to kill using wintergrass weed killer, but it has to be poisoned in about April, when the weeds are still tiny shoots. This needs to be done repetitively about every 2 weeks, according to the instructions on the bottle.
Much harder to kill with poison are two species of weed - creeping oxalis and corn speedwell. For these weeds, our options are very limited. This is creeping oxalis.
This is corn speedwell. When flowering, it has tiny blue flowers. So far, I had been controlling it by pulling out by hand.
I did experiments and tried covering the lawn with black plastic and pouring on boiling water from a steel watering can. First, I did a small test. Here is the test area on 6 August 2021:
As you can see, it is heavily infested with creeping oxalis, with more creeping oxalis than couch grass! Not much lawn to lose here, so ideal for an experiment.
On the right I covered with black plastic, on the left closer to the fence I used boiling water and further from the fence I used Roundup. Taken 15 August 2021:
And just after removing the plastic six weeks later:
The wintergrass and creeping oxalis kept re-appearing, and so was treated with repeated applications of boiling water. Nonetheless, covering with plastic seemed to be the most effective option - as can be seen above, it nearly wiped out the creeping oxalis. Therefore, I proceeded to use plastic for the rest of the lawn. I kept the time I covered the lawn to about 2 weeks, finding that most effective for the late spring and summer period when sunlight is the strongest. This photo is taken 27 November 2021.
When I stuck to 2 weeks, the lawn generally grew back quite well. Generally, the creeping oxalis was hit much harder than the lawn. However, much to my dismay I found the lawn really struggled to regrow under the eaves of the house and near the large bushes. This photo was taken 5 April 2022, over four months later, with weeds starting to take advantage of where the lawn was weak. Elsewhere, the creeping oxalis was much less than before.
More unfortunate was near the carport. This was taken 12 April 2022, 11 weeks after the plastic was removed. Here, the lawn has fared worse off.
However, there is still hope! Remember what the lawn looked like before in my test area? This is what it looks like as at 20 December 2022, with no boiling water treatment since 29 October 2021 (selective weed poison has been used for the past five years or so, this was continued):
Therefore, I intend to try boiling water over the whole lawn.
If you want to try for your lawn, you can either do using a hot water urn and steel watering can (slow) or hire a contractor to shower boiling water on using a professional machine. Such machines do exist specifically for killing weeds, like from GreenSteam. When I asked one contractor they gave a disclaimer saying they do not know what the long term effects will be for the lawn. Admittedly, neither do I but I don't have much to lose.
You can try black plastic but I don't recommend using it where the lawn is in shade or near trees or large bushes.
If you have a situation like mine and don't have much to lose, why not give boiling water a go. It is a very old and proven method for killing weeds. It will set you back a few hundred $ for a contractor but based on my testing so far it has very strong potential. I would have it applied in the middle of summer and apply fertiliser to the lawn afterwards so it grows back the fastest. When I applied the boiling water in late winter, the weeds grew back before the lawn so I had to keep re-applying.
Have fun poaching weeds! 🔥🚿🌈