Cut the zucchini into the desired sizes and shapes for freezing. Place a large pot on a stove. Fill it with well-salted water, and bring it to a full rolling boil. Blanch the cut zucchini in small batches for two to three minutes. The water should remain at a full boil the whole time. If it doesn't, you've put in too much zucchini. Remove them and start over once the water returns to a boil.