The terms candied ginger and crystallized ginger are interchangeable. Both describe a type of ginger preserved with sugar. You can purchase candied, or crystallized, ginger, or you can make your own. If you don't have time to either run to the store or make your own, you can even substitute plain fresh ginger or ginger powder and sugar in most recipes.
Make Your Own
To make your own candied or crystallized ginger, you need only sugar, ginger and water. Bring a batch of simple syrup -- made from equal parts sugar and water -- to boil in a saucepan. For each cup of ginger, use about 1 cup of sugar and 1 cup of water for the syrup, with additional sugar for coating the boiled ginger. Peel and chop the amount of fresh ginger root that you want to crystallize.
Candying and Storage
Boil chopped ginger root in the simple syrup for about 20 minutes, then strain it and roll or toss the boiled ginger in sugar. The boiled ginger will be wet and sticky, so the sugar will stick to the ginger pieces and absorb some of the moisture, keeping the candied ginger dry and in separate pieces. Once the ginger is "dry" from its roll in the sugar, either use it in your recipe or store it in an airtight container for up to three weeks in the refrigerator or at room temperature.
Substitute Grated Ginger Root
If your recipe calls for candied ginger, you can substitute either grated ginger root or ground ginger. Use one-fourth the amount of candied or crystallized ginger that the recipe calls for, plus sugar to taste. For example, if your recipe calls for 1/2 cup candied ginger -- which is 8 tbsp. -- use 2 tbsp. of grated ginger root plus 2 to 4 tbsp. sugar, depending upon your taste.
Substitute Ground Ginger
Ground ginger has a more concentrated flavor than grated ginger, so use less. About 1 tsp. of ground ginger is comparable to 1/2 cup of candied or crystallized ginger. You can add sugar to the substitution as well, depending upon the recipe and your tastes. It is easy to add more sugar but difficult to correct a too-sweet recipe, so start small. For each tsp. of ground ginger, start with 2 to 4 tbsp. sugar and add more, if necessary, to bring the recipe to the desired sweetness.