Use Pathclear or the like. Not normally a problem for dogs/ mogs but to be safer make it up as directed, put it in an old washing up liquid bottle and make sure it goes only into the gaps between the slabs. That will knock off weeds and keep them away for at least a couple of months, usually longer. However, the long term solution is - repoint the slabs
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The one weed that seems to survive Pathclear AND which will force it's way back through cement pointing is Mares Tail/ horses tail
Guess which one mum has in her garden ????
5 Precepts of Buddhism seem appropriate. Refrain from taking life. Refrain from taking that which is not given. Refrain from misconduct. Refrain from lying. Refrain from intoxicants which lead to loss of mindfulness