Renovating just half a lawn? Futile?

Hi,
Im renovating my small front lawns but just realised something. One of them I share with my neighbour. (see picture, mine is on the right) is it pointless for me to de-weed and de-moss and over seed etc if his grass is still connected to mine? will his weeds just come back over my garden?

 

Are you on friendly terms with the neighbour? If so, I'd suggest pooling resources and both of you doing both sides at the same time. Otherwise, I think you'd be ok just doing your side as long as you keep on top of it.

 

I agree with Clueless - and that way the whole garden will look neater with no seams!

 

Ive just asked him, he doesnt fancy it