Yes, you can grow sumac in an outdoor plant box! Sumac is a hardy and versatile plant that adapts well to container gardening, provided you meet its basic needs. Here’s how to ensure success:

1. Choose the Right Variety: Opt for smaller sumac species like Fragrant Sumac (Rhus aromatica) or Smooth Sumac (Rhus glabra), which are better suited for confined spaces.

2. Select a Spacious Plant Box: Sumac roots need room to spread. Use a large, sturdy plant box (at least 18-24 inches deep) with drainage holes to prevent waterlogging.

3. Soil and Sunlight: Plant sumac in well-draining soil mixed with compost. Place the box in a sunny spot—sumac thrives in full sun but tolerates partial shade.

4. Watering and Care: Water regularly to keep the soil moist but not soggy. Sumac is drought-tolerant once established, so reduce frequency over time.

5. Pruning and Maintenance: Trim back aggressive growth to maintain shape and prevent overcrowding. Sumac is low-maintenance but benefits from occasional pruning.

With proper care, your outdoor plant box can support a healthy sumac plant, adding vibrant foliage and seasonal interest to your garden or patio. Happy gardening!