For urban gardeners, the depth of your planter box is crucial for growing small root vegetables successfully. The general rule is to provide enough space for the edible root to develop fully without restriction.
For most small root vegetables like radishes, baby carrots, beets, and turnips, a planter box depth of 8 to 12 inches (20 to 30 cm) is sufficient. This allows for proper root development, adequate soil volume for nutrients and moisture, and ensures good drainage—a critical factor in container gardening.
Here’s a quick guide for specific vegetables:
* Radishes & Green Onions: 6-8 inches deep.
* Baby Carrots & Small Beets: 10-12 inches deep.
* Kohlrabi & Turnips: 12 inches deep.
Beyond depth, ensure your planter has drainage holes and is filled with a high-quality, well-draining potting mix. Deeper boxes (12+ inches) offer more buffer against drying out and temperature swings. By matching your planter's depth to your crop's needs, you'll harvest a bounty of fresh, home-grown roots from your smallest urban space.