Biochar for Houseplants
Blend charged biochar at 10 % of the potting mix when repotting. Improves aeration and extends the interval between deep drenches.
Last updated April 18, 2026
When to use biochar indoors
The best moment is repotting — when you are already mixing a fresh substrate. For a standard aroid, herb, or citrus potting mix, 10 % charged biochar adds pore space without changing drainage speed dramatically.
Rate and method
- Rate: ~10 % biochar by volume.
- Charge first: skipping charging indoors is more noticeable — interior plants take a couple of weeks longer to shrug off the initial equilibration. Soak in weak compost tea or fish emulsion for 24 hours before use.
- Blend thoroughly with the potting mix. Pot normally.
What to expect
- Longer interval between drenches
- Less soggy-soil during winter when plants transpire less
- A lighter potting mix weight when lifting larger pots
Coverage
One 6.5 L bag amends roughly 8–13 standard potting-mix repots at a 10 % blend. Plenty for an enthusiastic household collection.
Safety note
Wear a dust mask when blending indoors. Biochar produces a fine carbon dust if the bag is handled dry — the same caution that applies outdoors, more relevant in a smaller space.