Question: Patchy lawn in colour and growth

I received this excellent question in July 2019. A patchy lawn is a common issue and the possible causes of this case are worth exploring further.

Alex wrote:

Hi Kris,

I laid my lawn (turf rolls) almost exactly a year in July 2018. I prepared the surface and placed a rooting fertiliser before laying the turf. It was laid on topsoil provided by the developer who built our house (new build) and although not the best soil it seemed fairly good.

I fed the lawn in May with an all in one feed/conditioner and since then the growth and colour of the turf is all over the place. Some patches grow super fast and lovely thick green grass which grows at three times the pace of the rest, whilst other areas are pale green and others very dried out looking and straw-like down to the soil.

I’m not sure if I should scarify or rake or aerate the soil so any advice to get a consistent looking turf would be appreciated.

Alex

Thanks for the question Alex. There are a couple of issues going on here and the current look of your patchy lawn may be down to a combination of all of them.

Weed and feed problems

You state that the lawn is on poor quality soil. This does not appear to have been the main problem. A year on, the lawn does look like it has taken evenly. Laying turf is not ideal as the grasses in turf are often inferior species and can lead to problems further down the life of the lawn. For more details have a look at my post comparing seeding and turfing your new lawn. But overall, I would say the soil isn’t your main problem in this case.

You say that the lawn was fed in May 2019 with an all-in-one lawn feed. This looks like it could be the main cause of the patchiness. All-in-one type feeds tend to be of poor quality and are often very high in nitrogen. This stems from the market requiring “quick results” and “green up in 4 days”. The only way you can achieve these high claims from a lawn feed is to make them very strong. Almost dangerously so. Just a small amount of over feeding can cause major problems to your grass. They also come with the added difficulty of being very difficult to spread without the right equipment.

I think that patches of fast growth will be due to a larger amounts of lawn feed being dropped in those areas. I wouldn’t worry about this too much it does not seem to have damaged the grass. It will reduce in time. Just try to be more careful next time. Keeping the lawn well watered from now on will help to even out growth by washing the excess nutrients through to the subsoil.

For future lawn feeding, I recommend that you use better quality lawn feed and try to avoid all-in-one products. Ideally get in touch with your local independent lawn care service. They will be able to tailor a feeding programme for your grass using professional products not available in the shops.

A compacted patchy lawn

Another issue with your lawn could be soil compaction. However, this is difficult to tell from photographs and would need measuring on site. Different levels of compaction in soil produce different speeds of grass growth. This is because grass on a soft soil can put down a healthy, deep root run. On compacted soil the grass plant struggles to penetrate and the roots stay small. Healthy roots are the key to a healthy lawn.

I recommend aerating the lawn. Even if the problem does not turn out to be caused by compaction, an aeration treatment will always be beneficial. It will also help to reduce the likelihood of future compaction problems.

You do mention raking the lawn. I would only advise to do this in the autumn and only if it is needed. Your first step should always be aerating, especially on a lawn only a year old.

Fungal disease can cause a patchy lawn

I also believe that your lawn is infected with a fungal disease. During the summer a fungus is one of the main causes for a patchy lawn. Fungus infects grass leaves and reduces growth. It can also make the lawn look discoloured and untidy.

Fungal infections can be very common in the summer. Some grass species are much more susceptible than others. Fescue grasses and grasses which produce a large amount of thatch seem to be particularly vulnerable. Turf often contains a large proportion of these grass susceptible species. This is because they knit together and are easier to be lifted and moved. Unfortunately the stress of moving and their susceptibility mean that turf lawns often become infected with a fungus after they are laid.

From your pictures it is difficult to confirm which fungus is causing the problems. It could even be a combination of them. Pink patch and red thread certainly look to be the cause in your second picture. Compare this with a confirmed fungal infection pictured here.

The third photo looks a little more like a fusarium infection. This disease does make its way to the base of the grass plants and can kill the grass. Fusarium can do more damage than pink patch or red thread, but the treatments to remedy are the same.

Treating a fungal infection

To treat a fungal infection I would start by giving the lawn a balanced feed which contains good proportions of Nitrogen (N) and Potassium (K). Ideally do this after aerating. For example, an autumn feed. This will help to strengthen the grass and help it fight off the infection. If the lawn is no better after 3 weeks, then consider applying a professional fungicide. This will clear it up quickly. A fungicide treatment will need to be applied by a professional so contact your local lawn care service for help with this.

Many problems with lawn care stem from not being able to correctly identify problems. I hope this is helpful and you can take steps to bring your lawn back to its best.

Thanks for reading and let me know how you get on!

Kris Lord
The Lawn Man