Coco coir substrates have become increasingly popular for organic farmers and horticulturalists, thanks to their sustainability and ease of use, becoming even more popular still thanks to the rise of hydroponic farming . Coco peat, also known as coir pith, is very fine and fibrous, made from the soft, spongy material between the coconut husk's outer layer and inner shell . It holds moisture better than peat moss, while draining better than normal soil, helping keep the plant hydrated but also safe from root rot . Unlike rockwool, coco peat is very easy to handle, biodegradable, and quite cheap when compared with expanded clay pellets . Coco peat is also reusable through a combination of washing it to remove salts and contaminants, rehydration through soaking it in water, sterilization if necessary, and potentially adding fertilizers or compost for new crops .

The most effective coco peat formulations combine different particle sizes for optimal performance. Coco fiber is the long, strong strands from the outer husk used in making ropes or mats, while coir chips are larger pieces of the husk used for drainage and aeration in gardening . The best mixers for coco peat are perlite for plants needing good drainage and vermiculite for water-loving plants . Coco peat needs to have a moisture content of around 20-30 percent when packaged, otherwise it may dry out, or inversely become too wet, or even start to develop mold . Premium coco coir products are washed and buffered to ensure a pH of 6.0, similar to the soil acidity of a forest floor, and contain no fertiliser to give growers ultimate control over fertigation . RHP-certified coco coir is certified free from contamination with heavy metals, radioactivity, weeds, seeds, insects, plant and human pathogens .

Coco coir substrates are becoming increasingly popular worldwide, with global demand growing year-on-year in Europe, North America, and parts of Asia . Coco coir is often preferred in hydroponics as a substrate over things like Rockwool because it holds water well and provides aeration for plant roots . The sustainable nature of coco coir is a major advantage, as it is renewable, being a byproduct of coconut harvesting . Crops that respond best to coco coir include tomatoes, cucumbers, peppers, lettuce, strawberries, and various herbs . Even the waste from coco peat can be very useful, with dust and small pieces of coconut being recycled and put to use in mattresses and various other absorbent products, with even more of the wastage used in bioenergy .

Rockwool growing medium is the dominant grow media in commercial greenhouse vegetable and herb production worldwide . Rockwool is made by melting volcanic basalt rock and spinning it into mineral fiber cubes, slabs, and plugs . It provides exceptional water retention alongside excellent aeration—a difficult balance to achieve in any growing substrate . Commercial tomatoes are grown in 'pillows' of rockwool drip fed with nutrient solution that is re-used . Rockwool arrives with a naturally high pH and requires pre-soaking in pH-adjusted water (5.5–6.0) before use . It does not biodegrade, which requires disposal planning at end-of-life for commercial operations . Commercial hydroponic systems often use rockwool for propagation, with starter plugs for propagation, grow cubes for vegetative transplanting, and production slabs for drip-irrigated commercial systems .

The choice between coco coir and rockwool often depends on specific application requirements. While rockwool offers uniformity and proven commercial performance, coco coir provides sustainability and handling advantages. Coco coir production provides jobs and income to many coconut-growing regions, supporting local economies and helping diversify the agricultural industry . The industry is working to address concerns over potential over-harvesting of coco peat . As the demand for sustainable growing media grows, both coco coir substrates and rockwool growing medium will continue to play essential roles in hydroponic cultivation.