3. Cover with soil and mulch with 8 to 10cm of loose, clean straw. This will control weeds and temperature and retain moisture.
Garlic not a good match for containers
Because of its relatively deep roots, garlic is not very suitable for containers. If you don't have any other options, choose a very large container that is at least 20cm deep, and insulate it from the cold with straw, mulch or soil.