Select: Choose firm and crisp rhubarb stalks with a deep red color. Avoid stalks that are limp or have blemishes, as they may not freeze well.
Clean: Rinse the rhubarb stalks to remove any dirt. Trim off the ends and discard any leaves.
Slice: Cut the rhubarb stalks into ½ to 1-inch pieces.
Blanch (Optional): Blanching is not necessary for rhubarb but can help retain its color and texture during freezing. To blanch, briefly immerse the rhubarb in boiling water for 1 to 2 minutes, then transfer it immediately to an ice bath to stop the cooking process. Pat the blanched rhubarb dry.
Freeze: Place the sliced or blanched rhubarb on a parchment-lined baking sheet in a single layer, and freeze until solid.
Package: Place the rhubarb in airtight freezer-safe containers or freezer bags. Remove as much air as possible. Label and store the rhubarb in the freezer at a constant temperature of 0°F (-18°C) or below.