When starting an urban herb garden, one of the most common questions is about container depth. The good news is most culinary herbs are perfectly suited for container life and don't require extremely deep planters.
For the majority of popular herbs like basil, cilantro, oregano, thyme, mint, and parsley, a planter box depth of 6 to 12 inches is perfectly adequate. This depth provides enough room for their root systems to establish and access sufficient water and nutrients.
Some herbs have specific preferences. Mediterranean herbs like rosemary, lavender, and sage develop deeper root systems and will perform best in the deeper end of that range, around 10-12 inches. Conversely, many creeping herbs like thyme and oregano can manage in surprisingly shallow containers, sometimes as little as 4-6 inches deep.
The key factor for success is often not just depth, but proper drainage. Ensure your planter box has adequate drainage holes to prevent waterlogged soil, which is detrimental to most herbs. Using a well-draining potting mix rather than heavy garden soil is also crucial.
For a mixed herb planter, aim for a depth of at least 8-10 inches to comfortably accommodate a variety of herbs. This urban gardening approach allows you to enjoy fresh flavors right from your balcony, patio, or windowsill with minimal space.