I live in zone 2 which has very cold winters and the saskatoons grow very well here. On our property we have lots of wild bushes and harvest them whenever we can. We have noticed that there are years when the frost comes at inopportune times and kills the blossoms. This means that there will be no fruit that year. So we try to have enough on hand to last a couple of years in order to compensate for years where there is no harvest.
Our favorite way to process them is to freeze them in bags so that they are easily removed when wanted. They make a great topping for porridge or granola.
Another great idea is to mix them with equal portions of stewed rhubarb, add some sweetener and then heat the entire batch until it bubbles. Then can them in jars. The resulting fruit is almost like pie filling. Topped with cream, this makes a delightful dessert!