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Fire caused by smouldering dry peat in a terracotta plant pot

How this fire happened


A smouldering fire started in dry peat contained in a terracotta plant pot that was kept in the bathroom of a residential flat.

This plant pot had been left in a part of the bathroom where it received direct sunlight on a daily basis for approximately two months.

Consequently, it is believed that frequent and sustained exposure to direct sunlight caused sufficient heating of the dried peat in the pot to start a smouldering fire.

We are not entirely sure of the exact mechanism which led to combustion in this case - however, we believe being left in direct sunlight was a factor and either pyrophoric action* from continuous low level heating or some sort of spontaneous combustion was involved.

We would really appreciate if anyone has any similar stories (other Fire Investigators or members of the public) - to let us know.

It was known that the occupant was a smoker and this was considered as a possible cause during the investigation.


However it was ruled out in this case, as no remains of a cigarette were found and the occupant stated that she would not have stubbed out a cigarette in the pot.

*Pyrophoric action: The chemical decomposition of wood due to the continuous or intermittent application of heat.

The plant had died two months previously and since this time, it had been left unwatered in a corner of the bathroom that received direct sunlight.

On the day of the fire, at around 09:30 in the morning, the occupier noticed a smell she described as being similar to "burning paper".


Over the next 30 minutes, this smell became progressively stronger. As a result, the occupier searched the flat for the source of the smell and upon entering the bathroom, saw that it was filling with whitish-grey smoke.

As soon as she saw the smoke in the bathroom, the occupier took her daughter, exited the flat and called the fire service.

The fire service arrived and used a thermal imaging camera (TIC) to identify the heat source, which was found to be the peat in the plant pot.

The effect it had


"I was shocked because I never imagined a plant pot could catch light, I never thought in a million years that could happen.


The plant had died and, because it was my son's memory plant, I didn't have the heart to throw it away, so the soil was dry.

I went into the bathroom and saw it was filling up with smoke. When I saw all that smoke, I thought it was a fire but I had no idea where, because you couldn't actually see where the smoke was coming from.


Straight away I got my daughter, ran out my flat, and called 999.

I realise that, basically, you need to make sure that things like this aren't left in direct sunlight. I never thought this could happen"

Safety message​

We are not saying that plant pots should not be left on window sills, as this is clearly not appropriate or indeed practical!

However, this again demonstrates that fire can start at any time, anywhere for reasons you do not expect!

Fortunately, as soon as she realised there was a fire, the occupant did all the right things by immediately getting out with her daughter and calling the fire service.

Our safety message in this case would be:

  • Make sure that you have suitable working smoke detectors.

  • Make sure that you have a pre prepared action plan (this should also include considering what you will do with your pets - you should not be placing yourself at any risk).

  • Make sure that exit doors are easily openable and that you don't have to search for keys etc.

  • If you live in a block of flats (purpose built or converted) it is important that you are aware of relevant matters that should be identified in the premises Fire Risk Assessment. In particular, whether the general policy in case of fire is "Stay Put" or total evacuation (note: you should always evacuate if the fire is in your own flat). Further guidance and advice will be available on the "Fire Safety Order" by visiting your local Fire & Rescue Services web site.

Do not stub cigarettes out in plant pots, as whilst this was not found to be the cause of fire in this case - it has been found to be the cause in other fires where flower pots were involved.

Further home safety advice can be obtained from your local Fire & Rescue Service.

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