What is happening to my lawn

We had our lawn installed a few weeks before Christmas, and it took off quickly. We watered daily, as advised by our landscaper, which made sense given the dry Australian summer. Eventually, we reduced watering to every second day.

About a week and a half ago, we did the first mow, followed by a second mow a week later. However, as you can see in the pictures (current, after the first mow, and before mowing), the grass has turned dry and yellow.

Our landscaper applied Seasol new lawn fertilizer a few weeks after installation, but we haven’t fertilized since—I’m worried it might burn the grass and make things worse.

How can we tell if the lawn needs more or less water, fertilizer, or if it’s dealing with a disease? Any advice would be greatly appreciated…

I’m in the US, but my professor had a great saying about watering: grass is like children. If you feed and water them every day, they won’t grow their own roots. They need to venture out to find water. Start watering deeply but less often now that it’s established. This will encourage deeper roots, making for a healthier plant overall.

About the yellowing, you took off a decent chunk when you mowed, which stresses the plant that’s already struggling from the cut and the heat of summer. Keep watering every other day until it greens up and try to mow more often so you don’t take off too much at once.

For watering, aim for damp but not muddy or standing water. About 20 to 25 minutes every other day should work for your yard size, depending on your temperature a and soil type. Early morning, between 4 and 6 am, is the best time to water; avoid nighttime watering as it can lead to disease due to lingering moisture.

I’m not super familiar with the grass types you have there, but if it was installed by a local company and you’re concerned, it might be good to call them. Ask the owner or manager to swing by for a check-up. As a landscape business owner, I would be more than willing to drop by and see if you need help. Maybe offer them a beer or something for their trouble.

I think it’s probably fine, just a bit stressed from the first cuts and the heat.

It looks like a mower scalp. Stick to the 1/3 rule and mow more often. A lot of water and fertilizer means it’s growing more, which leads to more mowing!

New sod or grass doesn’t handle a hard cut well. As someone mentioned, check with your landscaper. Ease up on the mowing and raise the mower deck a few inches.

Do you have a lot of weeds in the before-mowed picture? You definitely waited too long to mow and probably scalped it, which could be causing more yellowing.

Ashton said:
Do you have a lot of weeds in the before-mowed picture? You definitely waited too long to mow and probably scalped it, which could be causing more yellowing.

There were definitely weeds along the edges which I pulled out, but no weeds elsewhere.

From what everyone has said, I can definitely see where we went wrong. This is our first home and garden experience, so it’s a learning process, but hopefully, some education and consistency will help us as we move forward.

It looks like the edges in the first picture are drying out.

This looks a lot like a disease issue. Also, be careful not to over-fertilize your sod.