Blackberry Pie Filling Canning Recipe – The Taste of Summer in a Jar - Not thorns in my finger tips or the 100 degree heat can keep me out of my blackberry patches this time of the year. Armed with a big straw hat, jeans, boots, a long sleeve shirt I headed to the blackberry patch for a marathon session of picking.  In just a couple hours I had the two gallons that I needed for my canned blackberry pie filling.