Hi @Gchip,
You still have a nice lawn and, considering more than 50% of the lawn is still relatively good, repair would be better than replacing. My suggestion is to carry out a lawn renovation, which is the process of restoring a tired or damaged lawn by improving the soil and grass health through steps such as weed control, aeration, dethatching, topdressing, and fertilising, so the existing grass can recover and thicken rather than being replaced.
You appear to have couch grass, which is a warm-season grass. This means now is the active growing season. Ideally, a renovation on warm-season grasses would be done in Spring when the weather starts to warm up, as this is when the active growing season starts, but as there is still warm weather on the horizon, meaning your lawn will still be actively growing, it should be fine to do it now.
Start by treating the weeds. Either of the products you've shown will be suitable for the control of common broadleaf weeds such as bindii, clovers or oxalis; however, they will not control onion grass. Our supplier, Lawn Solutions Australia have a product called Proforce Duke 100WG, which can be used to treat onion grass. Unfortunately, our stores do not keep it in stock, so you'd have to speak with your local store's Special Orders team if you'd like them to get it in for you.
After treating the weeds, you would get stuck into the main part of the lawn renovation, which involves cutting the lawn low, aerating and opening up the soil, dethatching, top dressing and fertilising.
Start by cutting the lawn low. This is referred to as scalping your lawn, and it helps to remove as much of the dead grass as possible, freeing up space for sideways growth as well as helping water, air and nutrients to get down to the root layer where they can be put to use. Set your mower to the lowest or second-lowest setting and cut it right back. This will appear to kill your lawn, but don't fret, it is not going to be dead as the roots are still alive and well beneath the surface.
You would then follow up by dethatching and scarifying your lawn, which removes further dead material, opening things up for air, water and nutrients. This can be done manually with a thatching rake, or with a tool such as this Ryobi One+ 18V Brushless Cordless Scarifier. Check out How To Dethatch Your Lawn for some guidance on this process.
The combination of scalping and scarifying will greatly reduce the amount of dead grass in the lawn, which opens up the room for healthy, green grass to take its place.
You would then aerate your lawn. This can be done with hand tools like a garden fork or aerator, or if you'd like speed up the process, you could also hire a Lawn Corer. Aerating will relieve compaction, improve air, water and nutrient movement to the roots, and encourage deeper, stronger growth. Check out How To Aerate Your Lawn for some guidance on this process.
After aerating, you will topdress the lawn. This helps to level out your lawn, which will encourage more even drainage. It will also add valuable nutrients to the soil that the grass can use to spread and thicken. Check out How To Topdress Your Lawn for some guidance.
After topdressing, apply a quality lawn fertiliser and ensure you give the grass plenty of water to ensure it has everything it needs to bounce back from the renovation. It would also be worth limiting the amount of traffic on the lawn for a few weeks while it bounces back.
Let me know what you think and if you have further questions, please don't hesitate to ask.
Jacob
