Home made weed killers

  VNAM75 16:07 07 Sep 2009

Does white vinegar work? Also heard adding washing up liquid and salt helps too. It's for a stoned patio area and there are no plants around.

What would make a good patio and block pave cleaner? I find the products you can buy quite expensive. I was thinking of diluted bleach or is that too strong?

  Quickbeam 16:12 07 Sep 2009

The proprietary brands of weed killer aren't expensive if you apply them with a sprayer. That allows you to use the stuff in a stronger solution without much waste over spray.

  johndrew 16:18 07 Sep 2009

click here for everything and click here excluding grass.

I also found some that suggested a cider base (perhaps sacrilege to some), cooking oil, paint remover and petrol!! The latter may be interesing if you have a barbecue the same day!!

  Chegs ®™ 18:12 07 Sep 2009

I have used bleach to kill a very large thistle as I hadnt any proper weedkiller to hand,it initially looked like I was going to have to buy some weedkiller as the thistle didnt appear to be in the least bit perturbed by the bleach.....then we had some rain,& the thistle expired the very next day.The thistle was growing through a crack in the pavement and housewall and had resisted attempts by the council to kill it with their rarely seen "ghostbuster" (guy with a pressure spray on his back)

  Stuartli 18:23 07 Sep 2009

The other half read recently that pouring water which has been used to boil potatoes works as a weedkiller between flagstone cracks.

So I tried it.

The weeds are still thriving.

  Bingalau 18:35 07 Sep 2009

Maybe the water should still be boiling and contain plenty of salt.

  Forum Editor 18:42 07 Sep 2009

has said it for me as far as chemical substances are concerned - don't make your own weedkillers. The proprietary products will do the job better anyway.

Use a Jet washer to clean your patio and block paving, but be aware that it will wreak havoc with faulty pointing around the patio slabs, so replace that first, and allow a week's curing time before you fire up the Karcher.

Rake out all the old pointing and replace it with a mix of four parts of sharp sand to one of cement. Mix it dry - there'll be enough moisture in the sand when it comes out of the polythene bag, and brush the mix into the joints with a soft broom - a wallpaper brush is actually the perfect tool. When the joints are nicely filled, take a nine-inch length of plastic garden hose and draw it along the joints, applying a degree of pressure; you'll soon get the idea, and you can top up the joints with more mix as required. You're aiming for a fairly well-compacted result that leaves you with a neat half-round joint without any of the mess associated with trying to use a pointing trowel and wet mortar. Brush up any residual mix - it will be dry and easy to collect.

Then hope for a light rain shower within 24 hours. If you don't get one, spray the whole area with a fine spray - don't let too much water wash into the joints.

Go away and leave it for a week, and then do the jet wash. It will work wonders.

  VNAM75 20:37 07 Sep 2009

Thanks everyone for the advice, I will stick with shop products.

FE, you gave me similiar advice to the above regarding patio laying/pointing a while ago. I have recently finished the patio and have a picture here (click to enlarge)

click here

It took me ages because as a novice, I'd dug out too much soil at first which meant I had to put most of it back in again. I laid the slabs one by one on a layer of sand (no mortar). Seems stable enough as the slabs are heavy. For the pointing I used a dry mix of 3:1 sharp sand/cement. For some areas I had to use building sand because I ran out of sharp sand. After brushing it in I used my finger to press in the mix (did not think of a garden hose at the time)- I don't think I was thorough enough though.

There was heavy rain for the next 2 days, followed by hot weather. Some of the pointing began to flake and crumble which I removed and refilled with new mix, this time I gave it a light spray of water after brushing it in. What could have caused the pointing to crumble - hot weather, heavy rain, sand/cement mix, not pressing in the joints hard enough? I also find dried mix pointing does not set as hard as a wet mortar mix, though its about 10 times quicker and easier to apply (for me).

  robgf 22:57 07 Sep 2009

If your slabs have algae, or moss on them, a bleach water mix (50/50) will kill it. The cheap supermarket bleach is good enough.

Sodium Chlorate would have been the best choice for the weeds, as it has a residual effect. But unfortunately the EU numpties have banned it.
PathClear appears to be useless, so the only choice is Glyphosate, which will kill the weeds, but only those that are showing.
Personally I use a patio knife and a stiff brush.

Be cautious when using a pressure cleaner, they are okay on blocks, but can damage some slabs and often roughen the surface of older concrete slabs.
Avoid pulling out pointing (as much as is possible), by keeping the lance at a shallow angle, or using a surface cleaner attachement.

  Bingalau 23:23 07 Sep 2009

I cleaned my paving slabs with a power washer and within a few weeks they were worse than before I cleaned them. What's the reason and the cure for that? Was there a protective coating on the slabs that I have washed off?

  Forum Editor 23:38 07 Sep 2009

There are several possibilities. Sometimes people don't lay with the joints wide enough - you need at least 12mm between the stones. Sometimes the mixture isn't properly compacted, and if this is the case the first drop of rain will wash the cement down through the joint, leaving a sand-rich surface, which flakes and separates very easily.

The dry mix will cure as hard as a wet mix, provided it is not totally dry when applied, and is compacted properly. Sharp sand will give a far better result than soft building sand, which tends to be 'fatty' and breaks up more easily in this context.

It's essential to dampen the finished joints fairly thoroughly within 12 hours of filling, otherwise the curing process will occur without sufficient moisture to give maximum hardness. The object of the exercise it to dampen without washing the cement down through the joint.

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