annoying neighbour

If it was me I would be able to use my Super Power." I'm sorry I can't hear what you are saying, I am deaf." Then I would just continue and ignore him. It is a great excuse and my actual level of deafness varies by how much I want to engage with folk.

Grey rock is your friend here. No reaction at all, keep doing what your doing and if he says anything go ' oh sorry, I'm so busy wasn't really listening'. He will get bored and move on if he gets no reaction.

Ooh I'd like to flash him a big smile and say, "Thank you for your help, I'll certainly bear it in mind."
Send him home happy, then carry on as you were 😁

Why people like this think you need their opinion always amazes me.

Can you say something like, "This is the way I've been advised to do it. When I want your advice, I will ask for it."

I hate folk like that,,,,they give their opinion whether you want it or not, or they say....now, what you should have done is..bla bla...

he is married i feel sorry for his wife his view on every subject is the right one in his eyes,

Ask him if he's very lonely and suggest a men's club.

Tell him straight that you don't want his advice. It's your garden and luckily there are no laws to stop you making it how you like.