Posted: May 14, 2012
Although fresh rhubarb is at its peak through May and June, harvesting can continue through the summer if plants have adequate water and don’t wilt from the intense heat of July and August. The quality is best if it can be pulled from the garden and used before it has a chance to dry. Choose rhubarb stems that are bright pink, crisp, and free of disease or insect damage. Pull the stems from ground level instead of cutting them. At any given time, harvest less than one-third of the stalks from any one plant. Rhubarb leaves are poisonous and should never be eaten.
To can rhubarb, select young, tender, well-colored stalks. An average of 10½ pounds is needed per canner load of 7 quarts; an average of 7 pounds is needed per canner load of 9 pints. Trim off leaves. Wash stalks, and cut in ½ to 1 inch pieces. Use the hot pack method of canning for rhubarb. In a large saucepan, add ½ to 1 cup sugar for each quart of fruit. Stir to coat rhubarb with the sugar. Let stand until juice appears. Heat gently until mixture boils. Fill jars immediately leaving ½ inch headspace. Remove air bubbles. Wipe jar rims. Adjust lids and process pint or quarts in a boiling water bath for 15 minutes at altitudes 1000 feet or below. (Process 20 minutes at altitudes of 1001 to 6000 feet and process 25 minutes above 6000 feet.) Note: It is not safe to add any type of thickening to rhubarb before canning because the starch will interfere with the transfer of heat to the center of the jar during processing. If you desire a thicker rhubarb sauce, add a little cornstarch, tapioca, or modified starch when you open the jar prior to serving.
Rhubarb freezes well. Rhubarb can be packed into containers or freezer bags raw or pre-heated. Raw rhubarb gives a good quality product without added sugar. According to the National Center for Home Food Preservation, heating rhubarb in boiling water one minute and cooling promptly in cold water helps retain color and flavor. (Cut stalks in lengths to fit freezer containers or bag before heating.) This step is similar to blanching vegetables. Watch the time closely as overcooking will cause it to lose its shape. A dry pack simply involves putting either raw or blanched rhubarb into containers without sugar leaving ½ inch head space. Individually quick freezing also works well with dry pack rhubarb. Spread a single layer of cut rhubarb on trays, freeze until firm (1 to 2 hours), then put in air tight bags or containers.
Rhubarb may be frozen with sugar or syrup if desired. For a sugar pack, mix 1 part sugar and 4 parts rhubarb and allow to stand until sugar is dissolved before packing into freezer containers. A syrup pack involves covering the rhubarb with syrup made by combining 1 cup sugar with 2 cups water and allowing adequate head space for expansion—½ inch for pints and 1 inch for quarts in wide top containers. In general, up to one-fourth of the sugar may be replaced with corn syrup or mild flavored honey. When cooking with rhubarb that is frozen in syrup, remember to include the sugar as part of the recipe.
Freezing already cooked rhubarb dishes saves time when serving. Plain sweetened sauces or those thickened with tapioca or ThermFlo® freeze well. Making a large recipe, using part of it immediately and freezing part for future use saves food preparation time. Breads, cakes, cobblers, and some pies freeze well, but don’t freeze rhubarb custard pies.