Can anyone advise affordable weed killer for patio

I have block paving to the rear of my house and need to get rid of the annoying weeds,could anyone advise me as to a product that wont break the bank I don't know if I should get a spray bottle or sachets which you add to the watering can,I tried the sachets years ago and they were pricey and did not cover half as much ground as they were supposed to,how long would I need to leave the weed killer to work before I could then use my jet washer and then apply kiln sand between grooves.
On a final note would using the jet wash dilute the weed killer and be counter productive although sometimes the weed killer can taint the blocks a little so I think it's a best idea to wash after and not before using weed killer

 

Hallo Alan
and welcome to Gardeners Corner. Someone will be along to offer advice - a bit late for most of them now but they will be around in the morning.

 

Depends how big an area you have, I've found bleach brushed over the area and left for a few hours as good as anything and it also cleans the paving.

Dilute the bleach - I do about 50:50 thick bleach with water, pour over the area with a watering can and then just give it a good brush.

 

Roundup - you would need to leave it for at least a week to do its job.

You can buy it in 5L in a pump bottle for less than £20

 

I second the roundup ... not cheap, but very good .... you need to make sure that after applying, there is no rain for at least 6 hours

 

When I do mine I pressure wash it first and then pour salt in the cracks. You could mix the salt into the sand and save a step. Then just spot salt when needed.

 

I may be wrong, but isn't 'Roundup' just a trade name for Glyphosate?

If you buy Bayer's Super Strength Glyphosate - which is pretty much Roundup by any other name, it comes pre-measured, just drop the soluble sachet in water, stir it about (follow the instructions) then apply. You can do it with a watering can or, as I do, with a Hozelock Killaspray. It works exactly the same as Roundup, i.e: ... don't apply if rain in expected in 6 hours: can kill some weeds in days, others take up to 4 weeks (although not in my experience): may need a second application: no need to exclude children or pets from treated area once it's dry and fully degrades in the soil.

It comes in 6, 12 or 18 size 8g packets: each sachet will cover 25 sq.m, so 6 sachets will do an area 150 sq.m: 12 sachets - 300 sq.m and 18 sachets - 450sq.m.

I've never bought anything larger than a 6-pack which costs £7 in Wilkinsons (the same thing is £9.50 on Amazon!). You can of course, buy 5 litres of Roundup in one of their fancy 'pump-and-go' thingies, but it'll cost between £12 and £18 and will still only treat 150sq.m - £7 or somewhere between £12 and £18? Your call.

 

Use a paint brush to apply it. Probably will use less and no drift onto other things either.

 

I've followed Bob Flowerdew's suggestion with success: "After you've made a cuppa, pour the surlpus hot water from the kettle along the cracks between the paving".

Works quite well and as you're using water that would only go cold, costs nothing!