In mid summer, some of our beds remained empty because of the seeds that failed to sprout. Instead of saving these beds for fall crops, we decided to try covering them to kill off all the weeds and prevent new ones from growing over the winter.
For most of the beds, we laid trash bags over them. We then pinned the bags down with the same U-shaped pins we used when installing the new hose. For one bed, we used an old tablecloth that had been used for live science demonstrations. The tablecloth will likely work better since it does not let as much sunlight through as the trash bags. You can see through the trash bags a little, but not through the tablecloth. Also, the trash bags rip and blow around easier, leaving a chance of them blowing away in a storm.
Both the tablecloth and trash bags will kill off the weeds by denying them water and sunlight for months. When we uncover the beds in the spring, they should therefore be bare, which will leave less prep work for us.