Content assessment guideline

A substrate certified in accordance with the RHP quality mark will not pose any threats to either humans and/or the environment. The RHP quality mark not only applies to the final substrate but also to the raw materials used in the substrate manufacture since these can influence the quality of the final substrate to a large extent. The substrate are always provided with suitable user instructions.

Who is this for?

Manufacturers of the substrates and the suppliers of raw materials used in the manufacture of these substrates.

When is this needed?

Growers and propagators, both professional and consumers, require substrates that are of high quality and are safe to use. RHP certified substrates guarantee that the substrate, when used correctly, meets these requirements.

What to do next?

Companies interested in certifying their products need to contact both RHP and Kiwa. Kiwa can be contacted via telephone or e-mail as stated above. Alternatively, you can complete the attached application form and we will contact you as soon as possible. The relevant quality requirements that your product has to comply with can be downloaded from

Once a certification agreement has been signed then an initial evaluation of your company and the to be certified product is carried out. After a successful evaluation the RHP quality mark can be applied to your certified products. This information is then published on both the RHP and Kiwa websites.