Garden centres are becoming much more than just stores selling plants and outdoor furniture as they look to fill the gaps left on our high streets. Bosses of popular sites across Kent have revealed plans to build mini golf courses, activity centres, and larger cafes to create a “destination” shopping experience and compete with online retailers. The new manager of Hawley Garden Centre, near Dartford, which was bought by Strood-based paving manufacturer Castacrete six months ago, Mike Oliver said he is diversifying to step up and fill the void left on the high street. The firm plans to expand t…