Where to buy Raspberry Tea Plant Food Fertilizers for Raspberry plants need to be are basic. Raspberry plant fertilizer should be a simple balance between NPK. For instance, the best fertilizer for raspberry plants is Raspberry plant food which all organic and a proper pH and balanced NPK. It is fast and easy to use. Just add water and set in the sun for a few hours. Use in place of watering and as often as you like as Raspberry Tea Plant Food has no chemicals therefore can't build up in your soil. Buy Raspberry Plant Food. Our Raspberry Plant Food is all organic and made right here at our farm. Throw a hand full into the trench where you are planting the Raspberry plant and mix into the soil. Give Raspberry Tea once new branches come above ground. And give Raspberry Tea about once a month.