Yes, you can grow a small elderberry bush in an outdoor plant box! Elderberries (Sambucus spp.) are versatile plants that adapt well to container gardening if given the right conditions. Here’s how to ensure success:

1. Choose the Right Variety: Opt for compact or dwarf elderberry varieties like ‘Black Lace’ or ‘Adams’ for better container growth.

2. Select a Spacious Plant Box: Ensure the box is at least 24 inches deep and wide to accommodate root growth.

3. Use Well-Draining Soil: Elderberries thrive in fertile, slightly acidic soil with good drainage. Mix compost for added nutrients.

4. Provide Full Sun: Place the plant box where it receives 6-8 hours of sunlight daily for optimal berry production.

5. Water Regularly: Keep the soil consistently moist but not waterlogged, especially during dry spells.

6. Prune Annually: Trim dead or overcrowded branches in late winter to promote healthy growth.

With proper care, your elderberry bush can flourish in a plant box, offering beautiful blooms and nutritious berries!