How to treat lawn turning yellow after fertilising?

Vismay

Hi everyone,

I’m after some advice regarding my lawn, which has recently started turning yellow in patches. I suspect it might be due to over-fertilisation. I used the Seasol 2 x 2L Ready-to-Use Lawn Fertiliser from Bunnings (link: https://www.bunnings.com.au/seasol-2-x-2l-ready-to-use-lawn-fertiliser-twin-pack_p2990044).

The product seemed straightforward to apply, but within a few days, I noticed some yellowing. The lawn was healthy and green before application. I’ve attached a couple of photos for reference — you can see the discolouration starting to appear.

Has anyone experienced this before with Seasol or other liquid fertilisers? Is it likely over-fertilisation, or could it be something else like watering issues or a reaction to weather?

Any tips on how to recover the lawn would be much appreciated!

Thanks in advance.

EricL

Hello @Vismay 

Based on the image and your description, it does look like your lawn is showing early signs of stress, particularly with the patchy yellowing that has appeared after applying the Seasol Ready-to-Use Lawn Fertiliser. While Seasol is generally a gentle, seaweed-based product designed more for root stimulation and overall health than strong feeding, it does contain some nutrients, and when applied in excess or unevenly—especially on already healthy turf—it can cause minor burning or leaf discolouration. This is more likely if applied during hot or sunny conditions, or if the lawn wasn’t watered in properly afterward. Another possibility is inconsistent application, where overlapping passes with the sprayer delivered too much product to some sections of the lawn.

It’s also worth considering environmental factors. If the weather was particularly warm or dry following the application, that can amplify any fertiliser effects and lead to patchy stress. Likewise, if the lawn wasn’t watered consistently in the days after application, or if your soil drains unevenly, some areas may be drying out faster than others. However, since the lawn was healthy and green beforehand, over-fertilisation or uneven spraying remains the most likely cause.

To help your lawn recover, avoid adding any more fertiliser for now. Instead, focus on deep, infrequent watering to flush excess nutrients through the soil—aim for a good soaking every few days rather than light daily watering. This encourages deeper root growth and helps leach out any excess. You might also consider mowing lightly and regularly, ensuring your mower blades are sharp to avoid further stressing the grass. Over the next few weeks, the healthy areas should bounce back, and the yellow patches will likely green up as the roots recover. If they persist, a gentle topdressing with compost or a light lawn soil mix can help encourage even regrowth. Keep an eye on the weather and watering habits during this recovery period, as consistent moisture and mild temperatures will be key to a full rebound.

If you need further assistance, please let us know.

Eric