Raspberries should be fed in smid spring (May/early June) . For an organic food, I’d suggest Espoma Bio-Tone mixed into the soil around each plant. Raspberries produce one crop. each year you’ll see two types of canes, the ones that will flower and produce berries and those that just grow but don’t flower. After the berries have been harvested, the canes that produced them should be cut to the ground. Leave any canes that didn’t produce flowers. They are the canes that will flower during their second year and then they get cut away. in other words, cut away all post berry canes…they will never bear berries again but leave non fruiting canes for the next years crop.