To overwinter Canna City of Portland bulbs in colder climates, follow these steps:
•Wait until the first frost has killed the foliage.
•Cut the stems back to about 4-6 inches above the ground.
•Carefully dig up the bulbs, taking care not to damage the roots.
•Gently brush off excess soil and let the bulbs dry for a few days in a well-ventilated area.
•Store the bulbs in a cool, dark, and dry place, such as a basement or garage, with temperatures between 40-50°F (4-10°C). Place the bulbs in a container filled with peat moss, sawdust, or vermiculite to help retain moisture.
• Check the bulbs periodically for signs of rot or mold and remove any affected bulbs to prevent the spread of disease.