Britons can make small tweaks to their homes and gardens before listing a property as these can make it more valuable. Experts warned of an invasive plant that could slash the value of your home. Japanese knotweed is a pest for any homeowner and it can grow up to three metres tall at this time of year. Unfortunately, it is difficult to remove, but if you don’t do this it could knock the value of your home by five to 20 per cent, according to experts at Stokemont. The average UK property price is £373,493 this month, according to Rightmove data released today, which means a 20 per cent price dr…