Weeds on driveway

[Slugsie]

My driveway (which is built with paving slabs) has been somewhat neglected over the past year, and as a result has a major problem with weeds (some as big as triffids ;) ) growing up between the slabs. I'm planning on tackling it in the near future, and wanted to get some advice.

My plan is as follows:

1. Remove the bigger clumps of weed
2. Lift the slabs
3. Put down some very strong weed killer
4. Check the level of the base (allowing for run-off) which I think is currently just sand on hardcore.
5. Re-lay the slabs, and 'grout' them.

Any advice on what weedkiller to use, and the best (read easiest) way to 'grout' the slabs to stop anything growing back for as long as possible?

TIA

[Peter Ashby]

I had similar triffids in full flower in our back yard (concrete slabs) earlier. I adopted the following strategy.

1. blitz them with glyphosate, blitz them good and proper, wet them all over.
2. Wait a week for the glyphosate to kill the roots then get a tool like I have. It is basically a flat piece of aluminium in a strong hook shape and a handle. You insert said tool between slabs and scrape out both plants and accumulated soil.
3. Sweep it all up regularly.
4. scrape the gaps regularly to prevent soil buildup and especially at the start of spring.

Peter

[Peter Ashby]

For the plant to die properly yes. but read the bottle, 7-10 days is enough to kill the roots, then its safe to remove things like dandelions without fear of root remnants sprouting.

Peter

[chris French]

In message , Slugsie writes

Other than the weeds, is the drive ok, or could it do with relaying anyway?

If it is otherwise ok I wouldn't bother with lifting the slabs, as someone else has said, glyphosphate (such as Roundup) will do the job of killing the growing weeds - this is a systemic weed killer - it is translocated through the plant and kills the roots as well. So it kills perennial weeds such as Dandelions etc.

Most of the weeds that are going to grow in this situation will be killed with one application. sometimes a big old Dandelion root may take a couple of goes.

It doesn't stop new weeds growing of course, but a further application is easy enough.

You could use Sodium Chlorate as this is a persistent weed killer, but I don't think ti would really get down into the ground- but note that if it gets into the soil where you want to grow anything else then it can take 6 months of more before stuff can grow there.

As for 'grouting' if the slabs have been tight laid (like pavements) there is little to do. You can try brushing in the sand they use for block paving, but I don't think it's make a lot of difference.

You need say about 10mm gap between the slabs so that you can mortar in between them. This will stop pretty much all of the weed growth as long as it stays sound.

If you do lift the slabs and relay them I wouldn't bother weed killing the ground. The weeds don't come up through the slabs, they germinate in the gaps and grow down into the soil.

For advice on the paving see Cormaic's site:

[Scott Mills]

In my experiance all weedkillers that are selective, or 'specially formulated for your driveway' are expensive and crap. I relaid my patio after moving in as year ago as it suffered the same problem. I ripped up the weeds, lifted the slabs, chuned the base, levelled it, poured loads of sodium chloate down and then put down bin liners (covering the whole area with no gaps) and relaid the slabs on top using some sand where necessary to level. "Grouted" with a sand / cement mix. I then oiled my spurs and went off into the sunset on my horse.

It does take a while, for me it was something like 8 slabs an hour but I'm slow, get bored doing things like this and it was hot... It is hard work but you only do it the once.

Nothing has grown back in over a year now and I've not done anything to it since either. I guess the bin liners stop any water getting to the roots (and washing the nasty weedkiller away).

Scott

[Chris Wilson]

Spray with a weed killer sprayer every 3 months using a Roundup copy (much, MUCH cheaper, usually more concentrated and just as good) and that should sort it, or even get some Dairy Hypochorite from a farm supply place (bleach) and water the slabs with that, diluted. Cleans the slabs like new, stops green mould and stops weeds growing. Be careful with it, but it has a multitude of uses, IMO.

[chris French]

In message , Slugsie writes

Shouldn't be to hard then to get that out and repoint it.

[The Natural Philosopher]

There are better thungs than Glyphosate for totall kill. Sodium Chlorate is one, and there are others (2-4 summat?)

Agreed totally., Just scrape out the much, or use a pressure washer as well.

Or, as in my case, mae a 6:1 sand cement mixture and brush in to the gaps. tamp down hard.

It goes off eventually.

Now tyou can simply pressure wash the area any time it gets 'seedy' :-)

After a few years rain frost and cars, it needs doing again. But not as often as weeding if you don't...

[Peter Ashby]

That sounds like a good idea. I thought of regrouting with sand on my slabs but being a biologist I realised it wouldn't take long for the sand to become an ideal growing mix. But with cement it would take a lot longer.

How hard would it be to scrape this out and redo after a few years?

Peter

[Frisket]

I know I'll regret asking but... couldn't sodium chlorate be added to the filling mix or would it just get washed away? Only asking as I have the same problem on the patio but the gaps between flags are too small to use a traditional "grout" - 3-4mm so a dry mix brushed in would seem ideal. Regards, Richard

[Paul Mc Cann]

Speay the interstices once a year with Simazine weedkiller. Unlike Roundup which works on growing weeds, Simazine lays on the surface and remains active in stopping weed growing.

Alternatively Jeyes fluid can be sprayed more regularly and will also help control moss .

Paul Mc Cann