Yes, elderberries can be grown in a container that is at least 2 feet deep and 3 feet wide. A half wine barrel works well. Be sure to use potting soil so that it drains well but add a bag of compost to the potting soil mix to pamper the plants. In May add a slow release plant food like Osmocote to the top of the soil and work this in following label instructions. Plants that bear fruit like Elderberries need micro nutrients as well as nitrogen and so a complete fertilizer with trace elements like Osmocote will work wonders. Best wishes for good health to your little granddaughter. Keep growing, Marianne Binetti