Resources / Soil basics
By Sawgrass Organics · Updated September 21, 2026 · 3 min read
Biochar is a porous, carbon-rich ingredient that can change how a potting mix holds water, exchanges air and retains nutrients. Its effect depends on the biochar and the complete blend. Seeing biochar on an ingredient list tells you something about the recipe, but it does not tell you exactly how often to water or feed your plants.
At Sawgrass Organics, our peat-free Potting Mix combines aged compost, coco coir and fine biochar. Here is what that ingredient means for container gardeners.
What is biochar?
Biochar starts as organic material, such as wood or crop residues, that is heated with little or no oxygen. This process, called pyrolysis, leaves a material rich in carbon. It creates a different product from ordinary composting, where microorganisms break down organic matter. Oklahoma State University Extension explains how biochar is produced.
How biochar affects water and air in a pot
Roots need moisture and oxygen. A potting mix must hold enough water while leaving room for air after excess water drains away. University of Maryland Extension describes why those spaces matter: water and air move through the spaces around growing-medium particles.
Biochar can alter those spaces and the amount of water a blend retains. The direction of the change is not universal: some combinations increase air space, while others decrease it. Feedstock, production conditions and treatment all affect the result. University of Georgia Extension reviews these differences in container mixes.
For a gardener, this means judging the finished mix and the plant together. Biochar on the label is not a reason to water on a fixed schedule or assume a pot cannot become too wet.
Does biochar hold nutrients?
Biochar can influence how nutrients are retained in a growing medium. That can be useful, but retention and plant availability are different things. A material may hold nutrients without making all of them immediately accessible to roots. Oklahoma State's biochar guidance emphasizes balancing biochar with plant nutrition. The whole growing system still needs an appropriate feeding plan.
Biochar, compost, fertilizer and charcoal: the differences
- Biochar: A carbon-rich material whose physical and chemical properties can influence a growing medium.
- Compost: Decomposed organic matter that contributes nutrients. Those nutrients are released over time and may not cover a plant's needs for an entire season, as Maryland Extension explains.
- Fertilizer: Used to supply plant nutrients. Biochar can contain nutrients, but its composition varies; it should not automatically replace fertilizer. Texas A&M AgriLife Extension discusses what to check.
- Cooking charcoal: Made for use as fuel. Choose a product intended for horticulture instead of substituting barbecue charcoal. University of Maine Extension explains the distinction between charcoal and biochar.
Should you add extra biochar to a ready-to-use mix?
Start with the mix as supplied and follow its directions. Adding a separate ingredient changes the recipe. There is no universal amount of biochar that suits every plant and growing medium. Its source material, production process, particle size and nutrient composition can all matter. Texas A&M's biochar guide recommends checking the material's analysis and stresses that blanket recommendations are unreliable.
If you enjoy making your own blends, use horticultural biochar with clear product information and directions. For straightforward repotting, a formulated mix removes the need to choose a biochar percentage yourself.
Our Sawgrass Organics Potting Mix is a ready-to-use blend for container growing. Choose a pot with drainage holes, follow the bag directions and check whether your plant needs a specialized growing medium.
Frequently asked questions
Will biochar prevent overwatering?
No. A mix containing biochar still needs suitable drainage and watering. Check moisture before watering and match your care to the plant's needs.
Does every peat-free mix contain biochar?
No. Peat-free describes the absence of peat, not a single recipe. Read the ingredient list to understand the blend. Our peat-free potting mix guide explains more.
How does biochar fit with coco coir?
They are separate ingredients in our blend. To learn more about coir and how it compares with peat, read Coco Coir vs. Peat Moss, or explore our gardening resources.