As winter approaches, urban gardeners need to prepare their planter boxes for freezing conditions to ensure plants survive until spring. Proper winterization protects both your plants and containers from cold damage.
Start by cleaning out annual plants and removing dead foliage to prevent disease. For perennial plants, apply a thick layer of mulch—about 3-4 inches—using straw, wood chips, or shredded leaves. This insulation protects roots from temperature fluctuations.
Move containers to sheltered locations against building walls or under eaves where they'll receive some protection from wind and precipitation. Grouping pots together creates additional insulation. For extremely cold-sensitive plants, consider moving containers to garages or sheds during the coldest weeks.
Elevate containers using pot feet or bricks to ensure proper drainage and prevent freezing to surfaces. Wrap containers in bubble wrap, burlap, or specialized horticultural fleece for extra insulation. This is particularly important for terracotta and ceramic pots that can crack when frozen.
Water plants moderately before hard freezes—moist soil retains heat better than dry soil—but avoid overwatering. For edible gardens, consider installing mini hoop houses with plastic sheeting over planter boxes. Remove protective coverings during warmer days to allow air circulation.
In early spring, gradually remove winter protections as temperatures stabilize. Your properly winterized planter boxes will reward you with healthy plants ready for the growing season.