All charcoal is fired in kilns. The biggest difference between horticultural charcoal and activated charcoal is the nitrogen, argon and other chemicals added during manufacturing. Orchid growers choose horticultural charcoal because it's cheaper, and fired without chemicals. Both types of char add oxygen and absorb bacteria in standing water.

Horticultural charcoal is usually made from fruitwood, bamboo, or coconut shells that are kiln-fired in a low-oxygen atmosphere called: pyrolysis. The oxygen reduction process changes the structure of the charcoal, making it more porous.
Activated chacoal is great stuff. It can be made from soft coal, wood, bamboo, or coconut shells. It's usually kiln-fired "in reduction", but slowly and to higher temperatures, making it more expensive. High quality activated char is used in hospitals to absorb toxins in the body. I buy activated charcoal capsules at the grocery store, and keep them at home for emergencies. Mixed with water, activated charcoal paste removes toxins from bee stings, mosquito and spider bites (so does epsom salt). One can use activated charcoal in orchid cultivation, but growers should know it may be made from soft coal, and likely has a cocktail of undisclosed chemicals added.
Horticultural charcoal is terrific for keeping water clean. We suggest using it in plant medium, and in trays. We change our "tray char" twice a year. It adds oxygen to the hydration water while filtering bacteria, rot and fungus.
Fertilizer burn from charcoal? No, contrary to old school thinking; charcoal doesn't cause 'salt burn'. In fact, it absorbs excess fertilizer in the tray, and stores it until the grower can replace it.
When it comes to high nitrogen in any plant food; I'm a big believer in the 'less is more' method. Over time, 'fertilizer salts' build-up in the sponge-like medium. Eventually, tender roots and pseudobulbs get chemical burns when more fertilizer-water is applied and re-hydrate the concentrated (dried) fertilizer "salts".
Leading members of NWOS always suggest washing drip trays as often as you fertilize, and hydrating the orchid medium with plain water berore fertilizing to avoid salt burn issues. 


Orchid growers have used horticultural charcoal as a water filter for years.
We suggest using it with gravel in hydration trays or inside our raku orchid pots'
built-in drainage ring.

We always suggest fertilizing with care. Less is more when it comes to fertilizers high in nitrogen.
Fertilizers can build up when the water evaporates, then re-hydrate when mixing with the new application of fertilizer. Horticultural charcoal in drip trays helps remove excess fertilizer in water.

We suggest dipping the entire raku orchid pot and plant plain water before fertilizing to help avoid 'fertilizer burn', or 'salt burn'.

Dry potting medium and any unglazed pottery need to be hydrated or fertilizer will concentrate there and chemically 'burn' air roots. Washing trays as often as you fertilize also helps growers avoid 'salt burn' issues.


We fire our unglazed orchid pottery in an oxygen reduction kiln using an old method called: raku.
O-Pots are naturally carbon-infused to help keep water clean.

We sell our pottery online to orchid growers all over the USA.
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