How do I get rid of heat related dead spots in my lawn?

Author: Stefan Palm   Date Posted: 2 January 2014 

If we’ve ever had a hot week, it’s the one just gone, with 7 days looking like this: 39, 40, 43, 43, 46, 40, 28. There is no doubt that weather to this extreme will test any ones garden.  Hot weather does two things; it dries out the soil and it can scorch the plant. Both these effects stress the plant to varying degrees, depending on what type of plant it is and how healthy it is.

When it comes to lawn, both these effects can stress it considerably. Cool season grasses such as Tall Fescue, rye and blue grass are the worst effected by heat and will need to be replaced when they get heat stressed and die down. Warm season varieties such as couch, kikuyu and buffalo won’t scorch so much but they will be effected by the drying soil. These lawns will go into dormancy rather than dying off if they don’t have enough water and tend to recover when conditions become more favourable. They will no doubt lose their colour but they generally don’t die which is good news in a hot climate like S.A.

The most common question we get asked during a heat wave is, “I’ve noticed a whole lot of dead spots come up in my lawn. They go a blue grey colour then die off – What do I do?”

In almost all accounts, the dead spots coincide with the hot weather and are a direct result of the heat. The next question quickly comes…  If the cause is hot weather / dry soil, why does the lawn dye in patches rather than the whole thing?

The answer is that soil does not wet evenly. Even if you put in a new soil when you laid your lawn, water will not soak into it uniformly. This results in an uneven root system. The roots will be short where the water pools on the surface and longer where the water soaks down deep.  When the hot weather comes, the lawn areas with the short roots will dry out first, the areas with the deep roots probably won’t be effected at all resulting in patchy dead looking spots . The other phenomenon to effect soils and cause this problem is called localised dry patch. This is where random patches of soil become non-wetting and repel water almost as if it were waxy. The same result happens. Because water doesn’t penetrate, the roots don’t go down deep and those patches dry out quickly.

The solution is the same for both problems – Apply a liquid wetting agent.

Liquid wetting agent breaks down the non wetting properties of the soil and allows the water (and nutrient) to uniformly and deeply soak in. It’s the elixir of life for a lawn suffering from water related stress and the first port of call for anyone wanting to deal with this problem. Apply it before a hot spell and reduce the likelihood of getting dead spots in the first place. Do it after a hot spell and you’ll speed up the recovery process. We have a Liquid wetting agent called Paul Munns Betta Wet. It’s available from our store at Hove or we can send it out to you with no delivery charge.

Of course this isn’t the solution to all dead spot related lawn problems but it will solve the majority of them. It’s the best place to start in solving heat related dead spots in your lawn.

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