Now's the time to cover your garden for the winter!
Benefits to covering the soil:
It protects the soil organisms from the cold
It helps to prevent erosion
It covers the weed seeds in the soil so they don't immediately sprout in the Spring
It helps to retain moisture
Pull all your annual plants, then cover the soil so it's not bare.
Some options for covering the soil:
Leaves/grass clippings
They'll settle with the rain and snow and some might blow away, so you want to put on at least 6 inches or so. The goal is to have at least 3 inches once they settle.
Cardboard
If you're using boxes that were left out for recycling, be sure to take the tape off first so you're not just adding plastic to your garden.
Depending on the thickness of the cardboard, you can put down a few layers. It breaks down faster than you might think!
Overlap the pieces of cardboard. The more you overlap, the fewer gaps there will be for weeds to get through.
Straw
Make sure you don't get hay! Hay has seeds in it, which can become weeds in your garden. Straw is just the stalks, so there shouldn't be any seeds in it.
Similar to leaves, straw will also settle with the rain and snow. Put on at least 6 inches so it'll settle down and you'll still have at least 3 inches of cover.
Tarp
Make sure it's UV rated so it won't disintegrate and spread plastic bits in your garden.
Put down enough weights so it doesn't blow away!
In the Spring, take off the tarp when you're ready to plant. If you used leaves, cardboard, or straw, you can just make a hole and transplant right into it. That way, your garden is mulched for the new season already!