The merits of hot water versus other methods of weed control

Different treatment methods for weed control

Effective and environmentally friendly – the best way to remove unwanted weeds is with hot water.

Why remove weeds?

Some plants are cultivated and ornamental, but weeds usually grow without any human intervention. For farming purposes, weeds sometimes need removing to protect crops, as they can get out of hand and take over growing areas.

Weeds can spread really quickly. In public areas in towns and cities weeds are usually removed to keep it looking clean and tidy. Weeds can also case damage to roads and can become accessibility hazards in pavements. They can also look unsightly and make a place feel unkempt.

Hot Water Hot Foam Hot Steam Hot Air Flame Devices Weed Brush Chemical Treatment
Low impact on environment
Low noise exposure for users
Can be used on all surfaces
High sustainability
High effectiveness
Low frequency applications required
Safe to use in public areas

Different treatment methods for weed control

Let’s compare the different treatment methods for weed control. In this instance we are comparing the usage of hot water, hot foam, hot air, flame devices, weed brush and chemical treatment.

Impact on the environment

Hot water, hot steam and weed brush have low impact on the environment but hot foam, hot air, air flame and chemical treatment certainly impact on the local environment.

Noise exposure

Hot water, hot foam and chemical treatment are certainly less noisy to implement over hot steam, hot air, air flame devices and weed brush.


Hot water, hot foam, hot steam and weed brush methods can be used on all surfaces. Hot air, flame devices and chemical treatment are, by their very nature, problematic and need to be treated with care.

Sustainability and effectiveness

The following methods of weed removal are classed as high sustainability and effective: hot water, hot foam and chemical treatment.

Frequency of applications

Hot water, hot foam and chemical treatment require fewer applications to control weeds than hot steam, hot air, flame treatment and weed brush.

Public spaces and safety

Of the weed control methods we are comparing, all are safe to use in public places, apart from flame devices and chemical treatments.

Can you really just use hot water for weed control?

There are a few ways you can kill weeds with heat. Though, as you can see from the table above, weed control with hot water is by far the most efficient in many ways.

Chemical herbicides do indeed kill weeds effectively, but the damage they cause is continuously being called to question by the public. It doesn’t impart a good public image to use these methods and a lot of companies and governing bodies are turning away from this method and looking for something more sustainable and chemical-free.

There are a few different methods on the market – but by far the most effective is hot water, taking in to account the different variables of each method, like how many applications are required, low cost and variety of surfaces and conditions it can be used on.

Morclean’s Weed Control System maintains a constant temperature, which allows the heat to penetrate the whole plant down to the root – unlike other treatments that use heat. Hot water is the only chemical-free method that can go all the way down to the root. The weed is, if not destroyed, severely weakened as it has essentially been cooked and the cells destroyed.

If hot water is applied, regrowth is discouraged and this means that the frequency needed to apply will decrease in the second year. Only three to four treatments are required through out the year, as a general rule. Some weeds you will find only need one application, but it does depend on the kind of weed.

Research shows that hot water of between approximately 42 and 95 Degrees Celsius will kill  weeds. Evidently the hotter the water then the more effective this process should be. Morclean’s range of machines are all thermostatically controlled up to 95 degrees and can apply constant hot water to the weeds for optimal performance.

For best results and minimal water temperature loss, the nozzle of the water application lance should be between 5cm and 15cm.

Looking at different methods of thermal weed control

Let’s take a closer look at some of the different methods of using heat to control weeds.

Steam weed control

Similarly to using the hot water method, steam treats weeds because of the high heat level. However, the steam rapidly looses heat to the atmosphere and struggles to retain the heat all the way down to the root of the plant. This leads to multiple applications needed for the same results. Due to the higher temperatures, more energy is required to heat the water in order to produce steam. Both these factors makes the steam system more expensive and time intensive, as it is a much slower process. It also cannot be used in all weathers.

Flame weed control

Flame weeding involves using an open flame and passing it over the unwanted weeds. This intense high heat burns away the weeds. Flame weeding is a method that has been used over many years, flaming  does offer immediate and visible results and can be relatively low cost.

Though, there are issues with the flame only burning the surface weed and not penetrating the roots below ground. This means that the weeds could be quick to recover and grow back, which therefore means more treatments needed, which increases costs.

Flame weeding can also cause damage to adjacent structures such as wooden fences, posts, sheds and buildings, where as a hot water based method of controlling weed causes no harm. There are also questions whether it is best for heath and safety with this method, and also it cannot be used in all weathers, and can be quite dangerous. Research shows that there is danger of dry areas catching alight in the summer months and it is generally  advised that when you are applying Flame Weed control that you apparently have a fire extinguisher or a water supply In the vicinity – which of course is not a requirement  for other methods such as hot water weed control. A safe distance between the flame and desirable plants, shrubs and trees must apparently always be kept by the operator. Additionally, the it would seem that the operator or contractor  must always confirm or not  with the local council if it is safe and permissible to run a flame weeder in the area, as it is not permitted  in some areas. Appropriate clothing to protect the operator from the heat and flames is always advised.

Hot Air Weed Control

Hot Air Weed Control is typically a burst of hot air is applied to the weed, which then decomposes naturally over a few days or so. Because the air is so hot, there is an apparent danger of scorching wooden posts and fences in the weed control  process.

Research demonstrates that this  method can also be quite costly due to the amount of power needed to heat the air to such a high temperature. This method also looses heat really quickly to the atmosphere, and therefore only applies the heat to the plants surface, and not deep inside the root. This seems to indicate  that the hot air method  won’t be particularly effective, and more applications would be required, again making the process more expensive

Hot Foam Method

The foam part of this method is designed to keep the heat in the ground, to allow the roots to be affected by the heat so it is not lost to the atmosphere. However, you are having to pay for an use the foam elements, which makes it more costly. It could also be seen as unsightly in public areas when first applied.

Research shows that there is also the impact of the foam on the environment – which is potentially more harmful than the extremely low impact that can be achieved by just water. There are also apparently questions raised on how effective the foam really is at keeping the heat in – as steam itself is lost to the atmosphere so quickly.

stages of hot water application to kill a weed

Morclean’s Weed Control System

  • Kills weeds with 100% hot water
  • No costly chemicals required
  • Natural product
  • Applies a consistent high temperature to penetrate the roots
  • Visible results instantly
  • No damage to the environment
  • No negative impacts on water, environment, humans or animals
  • Low cost solution
Close up of the hot water nozzle as it blasts weeds with hot water
hot water weed control machine
Demonstrating the control panel of the WCS/LH hot water weed controlling machine
Control weeds using hot water with this superb piece of Morclean Engineering kit!
Operatove applying chemical free weed control

Morclean’s Weed Control System using Hot Water

The heat exposure penetrates the surface of the plant and severely damages the plants cellular structure, all the way down to the root. This means in a few hours the pant looses all moisture and cannot retain any, and dehydrates and dies. It is easy to use, economical and safe in all locations.

The Morclean Weed Control System keeps a steady temperature, which means minimal temperature loss to the atmosphere. The plant is hit with a constant stream of very hot water, which penetrates the entire plant. This means not as many applications are needed – only if it is a particularly hardy weed. It also sterilises the soil and destroys any seeds in the process.

Why choose Morclean’s Weed Control System?

We believe that the hot water method is the clear winner in all aspects of weed control. Getting everything just right is a challenge, but we are confident that hot water ticks the boxes. This method remains gentle to the environment and surfaces, yet powerful in the way it can destroy the entire plant including the roots, therefore needing less applications in the long run. We can no longer depend on harsh polluting chemicals, and turn towards a more sustainable, yet efficient method of weed control.