Where temperatures drop below freezing for extended periods, you'll need to move the container into a protected spot. Why? Because in the garden, soil may freeze but it doesn't get as cold as the air temperature. During a cold spell, air temperature may dip into the teens or single digits (or colder), but the soil won't get nearly that cold. In a container, on the other hand, the mass of soil is small compared to the soil in the garden, so the cold air can penetrate more readily.
If the soil temperature drops too much the bulbs may be damaged.
Protecting Your Fall-Planted Bulbs in Containers
Here are a few ways to protect your bulb-filled containers:
- Move the pots into a shed, unheated garage or another place where temperatures remain cool but don't dip too far below freezing.
- Dig a hole in the garden large enough to accommodate the container. Place the pot in the hole, fill in around it with soil and add a blanket of loose mulch, like straw or leaves, over the top.
- Use chicken wire or hardware cloth to build a cylinder around the pot, then fill it with straw or leaves to insulate against the chill.