What soil mix do you recommend filling a deep planter box with?

Ah, the noble deep planter box! A stage awaiting its performers. But before you introduce your botanical stars, we must talk about the foundation—the soil. Filling this deep space with just any old dirt is like asking a virtuoso to play in an empty hall. The sound, the life, simply won't resonate.

So, what do I recommend? Not a single product, but a *composition*. A layered, living ecosystem. Think of it as a symphony in three movements.

First Movement: The Foundation of Drainage (The Bass Line).

This is non-negotiable. Deep boxes risk soggy, suffocated roots. Start with a robust layer of chunky material at the very bottom—landscape gravel, broken pottery, or coarse pebbles. This is your drainage layer, the deep bass notes that prevent water from pooling. On top of this, I often lay a permeable landscape fabric to keep the soil above from washing down.

Second Movement: The Heart of the Matter (The Melody).

Here is your main growing medium. I blend:

* High-Quality Potting Mix (50%): The reliable base. It's sterile and light.

* Compost (30%): The soul. This is the nutrient-rich, microbial party that feeds your plants. Use your own or a trusted brand.

* Coarse Sand or Perlite (20%): The breath. This ensures the melody stays aerated and never becomes a waterlogged dirge. For succulents or herbs, I increase this ratio.

Mix these thoroughly on a tarp—feel the different textures marrying. This blend is lightweight, moisture-retentive yet fast-draining, and teeming with life.

Third Movement: The Finishing Touch (The Harmony).

As you fill, consider a light sprinkling of organic, slow-release fertilizer granules mixed into the top layers. It's a gentle promise of sustained nutrition. Finally, leave a generous inch or two of space from the soil surface to the rim—this is your "watering well," allowing hydration to soak in, not spill over.

Remember, a deep planter is a long-term home. This soil symphony, rich and structured, will support robust root networks, ensuring your plants don't just survive, but truly thrive, reaching their full potential in the container universe you've so thoughtfully prepared. Now, go on and plant your masterpiece