Maintenance - Best weedkiller?

[maryk]

Does anyone know the best weedkiller to use that will a) destroy existing weeds b) keep weeds at bay for at least 6 months and c) not stain the blocks (Marshalls Drivesett Duo)?

I used a general purpose weedkiller in a spray (think it was Roundup) and not only did it not kill the weeds but it also left horrible white staining on the drive.

I have heard that a sodium chlorate based weedkiller such as Deadfast (Growing Success) is the best. Does anyone have any experience of this and does it stain?

Is it best to clean the blocks with a pressure washer before or after treating for weeds? Is there any chance of the pressure washer reducing the life of the blocks or being too abrasive?

Any assistance gratefully received.

[Rich H]

I would use sodium chlorate (any brand is fine) first. This will kill everything over a few days, then jet wash, then reapply kiln-dried sand once it's all bone-dry. It won't harm the paving at all. However, if you have lawn or borders adjacent be careful not to get the sc on it. It kills all plant life stone dead and will do for some time.

Round-up is a totally different product which is absorbed into the plant and MAY kill it off at the root. It's not effective on some plants, particularly larger ones, and it has no residual effect at all.

[maryk]

Thanks for that. Should I reapply the weedkiller after redoing the sand or will there be sufficient residual from the first application to keep it weed clear for a while?

[Dave_L]

The residual weedkiller left will be fine. I sprinkle it on my patio and then wet it up slightly and brush it about, leave for a couple hours then wash down sparingly.