Remove leaves, cut the bottom end off and remove any tough strings from the rhubarb stalks 

Wash the stalks and pat dry

Chop the rhubarb stalks into 1/2-inch to 1-inch pieces (or whatever size you normally cook with)

Measure 2 cups of chopped rhubarb and put in a resealable freezer bag (or use vacuum sealer bags).

Remove as much air from the bag as you can to prevent freezer burn and seal the bag. 

Label the bag and store in the freezer for up to 1 year. 

Prepare a rimmed baking sheet by lining it with parchment paper. Parchment paper isn't necessary, however, it makes transferring the frozen rhubarb pieces very easy. 

Lay the rhubarb pieces in a single layer on prepared baking sheet. 

Put the baking sheet in the freezer for several hours. 

Transfer the frozen pieces into resealable freezer bags and remove all the air to prevent freezer burn. 

Label the bag and store in the freezer for up to 1 year.