In regions where temperatures drop below freezing for extended periods, you'll need to move the container into a protected spot. Why? In the garden, soil may freeze, but it acts as a natural insulation that protects the bulbs, and it doesn't get as cold as the air temperature. During a cold spell, the air temperature may dip into the teens or single digits (or colder), but the soil won't get nearly that cold. However, in a container, the mass of soil is small so the cold air can penetrate more readily. If the soil temperature drops too much the bulbs may be damaged.
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 over the top, such as straw or leaves.
- 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.
Finally, in early spring once nighttime temperatures stay above freezing, remove any protective mulch or unearth the container, then move it to where you can enjoy the flowers to come.
In regions where temperatures don't drop below freezing, planting bulbs in containers is easy. Simply pot them up, planting them at the same depth you'd plant them in the garden.