The man is a pillock.
Why on earth should a postie be expected to barge through foliage or bend down to avoid his plants? In southern England it has been raining almost continuously for the past 24 hours. This bloke's hanging baskets will be soaking wet yet he expects his postie to make her way through the sodden leaves and blooms just to deliver his gas bill. Yes, the postie could bend down, but why should she, especially if she is carrying a sack of mail. Supposing she had to do that at each house?
Royal Mail are being too accommodating. His delivery service should be suspended forthwith and only restored when free and clear access to his front door becomes available again.