I have a 90X 90 m approx garden rented out. I’ve tried putting a plastic sheeting/membrane with gravel over the top, it’s been done twice and each time the grass grows through. Can anyone recommend a more long term approach to take where I don’t have to keep redoing it? What is the most low-maintenance way to keep the garden? Astro turf - expensive? Concrete? Grass - lots of maintenance? Thanks in advance! 