# Biochar-Coconut Shell Mixtures as Substrates for Phalaenopsis ‘Big Chili’

## TL;DR

This study shows that mixing biochar and coconut shell improves the growth of Phalaenopsis orchids compared to traditional moss.

## Contribution

The study introduces a sustainable biochar-coconut shell mixture as an effective alternative to non-renewable sphagnum moss for Phalaenopsis cultivation.

## Key findings

- The 1:2 biochar-coconut shell mix improved root volume by 38.49% and root biomass by 42.47%.
- Plant height and crown width increased by 7.55% and 6.68%, respectively, with the optimal mix.
- The mix provided better porosity, aeration, and nutrient availability than traditional substrates.

## Abstract

Phalaenopsis is a widely cultivated ornamental plant of considerable economic value worldwide. However, traditional growing medium, sphagnum moss, is limited and non-renewable. It also decomposes slowly and is prone to environmental issues. Therefore, there is an urgent need to identify more environmentally friendly and efficient alternatives. Biochar, a sustainable material with excellent physical and chemical properties, has been recognized as an effective promoter of plant growth. In this study, we investigated the influence of biochar derived from three raw materials (corn straw, bamboo, and walnut) mixed1 with coconut shell at ratios of 1:2, 1:10, and 4:1, on the growth of Phalaenopsis ‘Big Chili’. Over a 150-day controlled experiment, we evaluated multiple growth parameters, including plant height, crown width, total root length, total projected area, total surface area, and root volume. Compared to the traditional growing medium, the optimal biochar-coconut shell mixture (maize straw biochar: coconut shell = 1:2) increased plant height and crown width by 7.55% and 6.68%, respectively. Root metrics improved substantially, with total root length increasing by 10.96%, total projected area by 22.82%, total surface area by 22.14%, and root volume by 38.49%. Root biomass in the optimal treatment group increased by 42.47%, while aboveground and belowground dry weights increased by 6.16% and 77.11%, respectively. These improvements were closely associated with favorable substrate characteristics, including low bulk density, high total and water-holding porosity, moderate aeration, and adequate nutrient availability. These findings demonstrate that substrate characteristics critically influence plant performance and that biochar–coconut shell mixtures, particularly at a 1:2 ratio, represent a viable and sustainable alternative to sphagnum moss for commercial cultivation of Phalaenopsis.