Bonsai Soil Mix

Sybotanica lists these ingredients and volumes for its current Bonsai Mix. Use the same scoop to measure the main ingredients; the smaller additions do not have published fixed ratios.

• Coco coir: 2 parts for moisture buffering and fine-root contact
• Worm castings: 1 part for a modest nutrient fraction
• Perlite: 2½ parts for a light, open texture
• Pumice: 4 parts for durable mineral structure and drainage
• Small additions: Activated carbon and lava gravel; the supplier also lists organic nutrients
• How to mix: Use the same scoop for each numbered fraction, then incorporate the small additions evenly.
• Customisation: For trees demanding a leaner root zone, consider a higher mineral share; for moisture-sensitive fine roots, choose a suitable grading and monitor drying.

Use this mix for a bonsai substrate that supports fine roots, quick drainage and precise watering control.

• When to repot: repot when roots circle the pot heavily, when soil stays wet too long or when the structure has clearly broken down.
• Root work: gently comb out old soil and prune dead or overly long roots with sharp, sterilised scissors. Rinse only where compacted soil cannot be removed safely by hand.
• Pot preparation: choose a bonsai pot with ample drainage holes, cover holes with mesh if needed and add enough Bonsai Soil Mix so the tree sits at the right height.
• Positioning the tree: spread roots radially, then backfill with mix, working it carefully between roots with a chopstick or similar tool.
• Settling the substrate: tap the pot and lightly firm the mix to remove hidden air pockets without compacting it.
• First watering: water thoroughly until runoff is clear; this helps settle the mix and rehydrate pumice and perlite.
• Ongoing watering: allow the surface to dry slightly between waterings but do not let the entire root ball stay bone dry for long periods, especially in full sun or wind.
• Feeding: because bonsai live in limited soil volume, use regular, moderate fertilisation on top of the nutrients already present in the mix.

• pH: approx. 6.9.
• EC: around 1.1.
• NPK (mg/L): roughly 285 – 12 – 133.
• Organic matter: about 31 %.
• Dry matter: about 69 %.
• Water retention capacity: around 26 %, tuned for frequent but controlled watering.
• Structural stability: typically 3–4 years indoors; coconut-based and other organic ingredients gradually change over time, while mineral components stay stable.
• Bioactive? Yes – compatible with bioactive bonsai or open planted containers.
• Pet considerations: No – contains perlite, fertiliser and activated carbon and is not intended for ingestion by pets or children.