This is the finding of an ongoing project by Hadlow College BSc commercial horticulture student Elizabeth Spackman.
She is using the three alternative media - Fytocell, EkoFibre and coir-peat - to see if there is a viable replacement for rockwool in hydroponic cultures.
Spackman said: "Sustainability issues are at the forefront of today's fresh produce sector, which may lead to rockwool becoming obsolete due to its high energy use in the manufacturing process and its end-of-life destination as landfill."
She said that Fytocell is a polymer of urea and formaldehyde and is created "cold" - meaning that no energy is used in its creation.
EkoFibre is made from 100 percent lignin cellulose wood fibres that are harvested from Forest Stewardship Council-certified sustainable forests.
Coir-peat is organic and - in its unprocessed form - is a waste product in its countries of origin as it is manufactured from the outside layer of husk that surrounds the shell of coconuts.
Fytocell, EkoFibre and coir-peat can all be composted at the end of their usage, so growers have a by-product in the form of compost.
Spackman said: "To date, no reductions in yields have been observed on the three growing media when compared to using rockwool."
The peppers grown in the media are delivered to local farm shops and restaurants. The college is working towards an Assured Produce accreditation so that it can supply local stores of major retailers.
Next year - the third year of pepper production at Hadlow - will see a further doubling of the scale of production with a view to supplying major outlets.