We had some weeds in the garden (well more than some we had lots). To get rid of them we bought a weed killer and it worked really well on the paving slabs. Its took about 2 hours to completely kill the weeds. With this in mind I put the camera on one and sprayed it with the killer. Below is a 2 hour time lapse of the whole event. The plant also with some magic editing comes back to life!
P.S The weed killer is pet friendly so the birds should be fine.