Freeze rhubarb by cutting the stalks into 1-inch long pieces, blanching them briefly in boiling water, drying them thoroughly and placing the pieces into a freezer on a baking sheet. After the pieces are completely frozen, place them in freezer bags, and keep them in the freezer for up to four months before using them.
Significantly improve frozen rhubarb shelf life by packing the pieces in a preservative-rich sugar solution in a wet-pack storage method. After completely freezing the rhubarb pieces, the next step in the wet-pack process is preparing a sugar solution. The simplest type of sugar solution is regular fruit juice. However, fruit juice imparts flavors to the rhubarb that can be either beneficial or undesirable depending on your preferences. Most wet-pack methods use a sugar solution produced by boiling water and sugar in varying ratios.
After using fruit juice or making your own sugar solution, mix the frozen rhubarb pieces with the solution, and place the combined mixture into a large freezer bag. Remove as much air as possible from the bag before placing it in the freezer. If you are using a vacuum sealer, freeze the combined mixture first, and then remove the air using the vacuum pump the next day. Sugar's preservative effects improve the shelf life of wet-pack frozen rhubarb, increasing it to as much as 12 months.