weedproof
/ˈwiːdpʊf/ or /ˈwiːdˌpruːf/Definitions
1. adjective
capable of preventing weeds from growing or being difficult for them to grow
“The company’s weedproof lawn treatment has been a huge success.”
2. noun
a surface or substance that is treated to prevent weeds from growing on it
“The weedproof coating on the patio has made it easy to maintain.”