Why Is My Lawn Yellow?

Why Is My Lawn Yellow?

A yellowing lawn is one of the most common problems faced by homeowners and garden enthusiasts. When lush green grass begins to fade to yellow, it’s a sign that something isn’t quite right, either in the soil, with the turf itself, or in how the lawn is being managed. The good news is that most causes of yellow grass are treatable with the right diagnosis and response. Understanding the reason behind the discolouration is the first step toward restoring your lawn’s health and colour.

Lack of Nutrients

One of the most frequent reasons for a yellow lawn is nutrient deficiency, particularly a shortage of nitrogen. Grass needs nitrogen to produce chlorophyllthe pigment that gives it a rich green colour. If nitrogen is lacking, grass begins to pale and eventually turns yellow. This is common in lawns that haven’t been fed regularly, especially in spring or summer when growth is most active.

Applying a balanced fertiliser, or a high-nitrogen spring-summer feed, will usually help restore green colour within a week or two. Always feed when the grass is actively growing, and avoid over-fertilising, which can cause more harm than good.

Overwatering or Poor Drainage

Too much water can be just as damaging as too little. A lawn that stays waterlogged for long periods is likely to turn yellow due to root suffocation and nutrient leaching. Grass roots need oxygen as well as moisture, and saturated soil deprives them of both. If the lawn feels spongy or shows signs of pooling, drainage may need improving through aeration or levelling.

Watering should be infrequent but deep allowing the soil to dry slightly between watering encourages stronger root growth and better colour.

Scalping or Mowing Too Low

Mowing the lawn too short can quickly lead to yellowing. Cutting grass below its ideal height removes too much leaf area, reducing its ability to photosynthesise and triggering stress. This is especially noticeable during dry or hot periods when the grass is already under pressure.

For most UK lawns, it’s best to keep the mower blade high and only remove the top third of growth at any one time. If the lawn has already been scalped, allow it to grow out for a few weeks before resuming regular mowing.

Dog Urine and Localised Spots

If yellow patches appear in isolated spots, often with a dark green edgethen dog urine is a likely cause. Urine contains high levels of nitrogen and salts that burn the grass when concentrated in one place. Over time, these patches can become more widespread if the dog returns to the same spot repeatedly.

Flushing the area with water immediately after your dog wees can help dilute the concentration. Damaged patches can be reseeded once the soil has recovered.

Compacted Soil

In high-traffic areas, yellowing can be caused by compacted soil. When soil becomes compressed, air and water struggle to reach the root zone. This weakens the grass and can make it more prone to yellowing or browning. Aerating the lawn helps relieve compaction, allowing the roots to breathe and the grass to regain strength.

Compaction is especially common along footpaths, play areas, or anywhere heavy items like garden furniture sit for extended periods.

Disease or Fungal Infection

Sometimes yellowing is caused by fungal issues, such as red thread or fusarium. These often appear during mild, damp weather and may be accompanied by patches of thinning or dead grass. Fungal problems are more likely to affect lawns with poor airflow, excessive thatch, or overfeeding.

In most cases, improving lawn health through proper mowing, aeration and feeding will help grass recover without the need for chemical treatment.

Final Word

A yellow lawn can be caused by a variety of issues, from nutrient deficiencies to overwatering, poor mowing or pet damage. The key is to assess the symptoms carefully, treat the underlying cause, and support recovery through consistent care. With the right action, your lawn can return to full health and regain its vibrant green colour in just a few weeks.