What will change in the RHP product certification scheme this year?

27 maRCH 2018

The RHP quality mark is a quality mark that is constantly in development and considers the market developments. The RHP product certification scheme is updated annually. From 1 May the new standards are effective. What are the most important changes?

Below the most important resolutions of the Central Board of Experts have been extracted. Certified companies must have implemented all changes of the RHP product certification scheme in their procedures and quality management system before 1 May.

Biostimulants in RHP certified substrates (module 300)

RHP has noticed an increase in the use of biostimulants in substrates. These products are said to often have an indirect fertilising value, by reducing abiotic stress or addition of micro-organisms that enhance nutrient uptake. There is a great need for a legal frame to market these products and it should be clear which claim the product carries. Biostimulants become part of the ‘EU Fertiliser Regulation’ and that is an incentive for the development of univocal standards and testing.

Biostimulants that are present at an ‘RHP site’ may not be a risk to the other products at the site and have to comply with at least the general product requirements and the general phytosanitary product requirements from the module General product requirements Horticulture (MOD 330).

Safe and controlled application
RHP advocates a controlled introduction and application of microbial biostimulants in substrates, retaining the RHP quality mark on the substrate. The policy here is:

  •  controlling risks
  •  proving product safety
  •  practical application

Biostimulants can be qualified as B or BE product. BE (B-exemption) is a new category of constituents under the RHP quality mark. These are products that do not carry the RHP quality mark but with a specific statement on the delivery note they are allowed to be processed in RHP products if they comply with the product requirements as stated in the product certification scheme. The supplier has to prove this with analysis results. Some products have received an exemption as BE product for processing in RHP substrates. You will find an overview of these products in the list of B products on My RHP (under Documents for RHP certification).

Bark (module 410)

In the module for bark the standards for phytosanitary demand have been added. Bark from Portugal is hygienised to mitigate phytosanitary risks. It is important that it is objectively determined that (steam)equipment, with which the hygienisation process is executed, functions well. The whole product stream that goes through the equipment, must be subjected to the right temperature and time. RHP performs a risk inventory at the concerning sites and a phytosanitary test. The phytosanitary test consists of an amount of dormant spores of the bacterium Bacillus globigii that goes with the bark through the equipment. Afterwards the remaining number of spores are measured. This shows the reduction of spores, i.e. the effectiveness of the system. This Bacillus-species is harmless to human, plant and animal and therefore can be used without risks in equipment. In addition to Bacillus also tomato seeds are led through the hygienisation process. The tomato seeds are supposed not to germinate anymore after the process. The phytosanitary test is a new 'tool' for RHP to control hygienisation processes and compare them to each other.

Mulch (module 715)

Mulches are used in for example the pot plant cultures to control weeds and to decrease evaporation from the potting soil. Not all mulches can be used like that without risk. To test mulch, RHP has developed a method with which the plant safety can be tested. In this new module for mulch it is described which products are permitted as mulch and what the additional process- and product specific requirements are. Mulches are products that consist of various raw materials from category A (RHP quality mark) and/or B  which are not an end product or RHP raw material yet. It has also been described in this module how to deal with counter samples and inspections.

Further changes in RHP product certification scheme




In this module for bark the standards for the sieve fraction has been added. The requirements for respiration have been cancelled.


For RHP compost the frequency of the chemical test of the Mn-active contents (method M18) has been changed to once a year (instead of once per 3.000 m3).

From this year putrescible raw materials for composting are allowed as raw material for RHP compost with Horticulture as the field of application if all other requirements are complied with.


For lime products an RHP method number (M33) for the chemical test of the neutralising value has been included. This refers to EN 12945.


This a new module for semi-finished products or a mixture of RHP raw materials, meant to be used in a substrate or potting soil. In the scheme the general, chemical, physical and phytosanitary requirements for semi-finished products have been described. Also the requirements for counter samples and inspection visits have been described in this module.

Notice all changes in the scheme

Not all changes are stated in this news item. All changes are marked in red in the RHP product certification scheme on My RHP. You'll find the changed modules in the table of contents; these are marked in red. Don’t you have a personal account yet? As employee of an RHP certified company you can easily create this yourself at my.rhp.nl.

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