Pick Your Own, it is a great resource for anything you might want to can. The process couldn't be much easier and you can use it for any kind of citrus fruit you might have. You can even mix different types of citrus together.
In the grocery store canned mandarins run about $4.00 per can. I'm actually thinking even with shipping I might be saving money by doing it myself.
How to Can Mandarin Oranges
adapted from Pick Your Own
1. Clean your jars, rings and lids. A dishwasher works great for this. I usually put them in a pot of boiling water and then place them in the oven on the lowest temperature while I prepare my fruit.
2. Peel your mandarins. Remove as much of the white pith as possible. These little Kishu Mandarins took no work at all to remove the pith, but their smaller than golf ball size did involve a lot of peeling.
3. Pull apart the segments. You can actually leave them whole if you prefer, but since I will mostly be using them for salads I decided it would be easier to separate them before the canning process.
4. Pack sterilized jars with Mandarin segments, leaving about 1/2 space at the top of the jar.
5. Prepare your syrup solution. It is up to you whether you want a light or thick syrup and adjust the amount of sugar accordingly. The sugar does not actually preserve the mandarins. Preservation is achieved through the canning process and water bath technique. You could just add hot water to the jars if you wanted no added sugar. I went with a 2:1 ratio of sugar to water. I found I used about 1/2 cup of solution for each pint of mandarins. I combined 6 cups of water with 3 cups of sugar. Place the solution over medium high heat stirring to dissolve the sugar. Bring solution to a boil and immediately pour over packed jars of fruit. Slide a knife down the edge of each jar to release any air bubbles. I found an offset spatula worked great for this step.
6. Place lids and rings on jars.
7. Place jars in a boiling water bath and boil for 15 minutes. You will need to adjust the time if you are living above 6,00 feet.
8. Ensure the jars are sealed. Any unsealed jars should go directly into the fridge. Sealed jars can be stored in a cool dark place for up to 9 months.