How to stop weeds in block paving

Weeds in block paving

Block paving is a popular choice for driveways and patios in Preston and the UK. Its robust, great looking, load bearing and not too expensive. But weeds often grow through block paving and ruin the look. They need digging out time and again. This is a chore that we can all do without.

Even weed proof membrane can only do so much. The weeds grow in the gaps between the blocks. So how to we stop weeds growing through our block paving? How do we reclaim the Saturday afternoons wasted on this unrewarding chore?

The top three methods used on block paving in Preston are:

  1. Weed killer
  2. Salt
  3. Block paving sealant

Weed killer

Round up weedkiller

Summary: Can work well but you need the right type and regular application.

There are hundreds of different variations of weed killer available to the public. Weed killer can be an effective way to keep the drive clean but will need to be redone on a regular basis. There are more powerful weed killers which are more permanent but they have very negative effects on the environment.

Different types of weed killer will be effective in different situations. Here is a quick breakdown of the most common types.

Contact weed killer

Contact weed killer will work if you have a flourishing array of weeds in your block paving. Glyphosate is a common example of contact weed killer. It works when absorbed through the leaves of a plant but is ineffective in the soil.

Systemic weed killer

The most common type of weed killer, systemic weed killer works its way through plants to kill each part of them including the roots.

Residual weed killer

Residual weed killer can be a good idea on block paving but you need to use it with care. Residual weed killer poisons the ground and stops weeds growing until it is washed from the soil. Just be aware that if you spray the block paving then walk into a grass area or near other plants it can kill those too.

Selective and non selective weed killer

All of the above types of weed killer come in two varieties: Selective and non selective. You can probably guess what this means but just to confirm: Selective weed killers will only work on specific plants. Non selective weed killers will kill everything they touch.

When choosing weed killer it is important to consider the effect you want to have and the potential negative side effects. There is no point spraying block paving with contact weedkiller as it will have no effect. Make sure that you will not contaminate unintended areas with herbicide.

Weed killer can take some time and up to 3 applications to completely kill off weeds. This can take up to a month depending on how stubborn your weeds are. The name of the game is persistence and patience.



Summary: Very cheap but can easily contaminate surrounding areas. Needs regular re-application.

Is using salt solutions to kill weeds in block paving just an old wives tale or can it be effective?

Salt has been used to stop things growing throughout history and it is no less effective today. A high salt content can make earth unsuitable for weeds and plants alike. Salt can be a cost effective way of keeping the weeds at bay due to its extremely low cost.

How should salt be used?

Salt can keep the weeds away for months or even years however it is non-selective and will kill everything. Make sure if you use it that you do not let it leach into other areas.

Salt will wash away with rain over time so it is advisable to re apply a solution to your block paving every 6 months.

How should salt be applied?

Some opt for road salt, this is effective but is applied as grit which you may not want. Another way is to make a saturated salt solution and use a watering can to apply.  

Salt is a kind of cheap but scatter gun approach to weed killing. We would advise against its use in close proximity to things you don’t want to kill. However block paving is usually separated from plants so it’s one of the few surfaces that salt can work well for.

Block Paving Sealant

Resin sealed block paving

Summary: Most expensive but most effective.

Of the three weed treatments mentioned here, sealing is the only one which may come close to permanent. Weeds grow in block paving because seeds/spores fall into the sand in the block paving gaps. They take root and begin to flourish into the annoyances that they are.

Sealing the block paving can stop this happening.

But sealant is also fairly risky and may be ineffective if you go for a cheap sealant. Always test any sealant you get on a small area before applying to the area. We have seen a few block paving disasters in Preston because of sealing with bad quality sealant.

Polyurethane sealants are what we recommend for block paving. There are many other types available but they are poorer quality and not as effective. The extra price you pay for polyurethane is justified as it solidifies the sand joints and create a long lasting seal on the surface.

This is the closest you can get to permanently stopping weeds growing through your block paving.

Warning: polyurethane sealant should not be used on clay blocks.


Weeds in block paving 2

Stopping weeds growing where we don’t want them is a challenge to every house proud homeowner. Above we covered the three most common methods for weed prevention in block paving.

They are all popular and effective but with different implications. For those that value their time a high quality block paving sealant will be the best option. For those that don’t want to spend their hard earned cash, salt may be best. For the people who are somewhere in the middle, weed killers may work best.

We hope you have found this short guide useful. If you would like a quote for block paving sealant, please get in touch.

Services: paving, block paving

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