An ode to the founding fathers of RHP 

30 june 2021

In recent years, we have lost three important RHP veterans. All three made a major contribution to the establishment and development of RHP. An ode to the founding fathers of RHP.

Jan de Maa

Jan de Maa was one of the potting soil manufacturers from the very beginning. After having fulfilled various positions in horticulture, he started a potting soil company for Comtu in the 1960s. Jan quickly saw that something was going wrong in the sector, due to a lack of knowledge in the preparation and use of substrates. He was one of the first to enter the Dutch “Proefstation” (research station) to draw attention to this problem. He did this with the knowledge that substrates could become very important in horticulture. After all, at that time people mainly worked with ordinary soil,

sometimes with an organic matter as an addition. In practice, Jan became the man behind many initiatives aimed at raising the sector to a higher level. Thanks to his vision for the future and bold approach, he succeeded. He embraced the initiative to set up a scheme for potting soil companies, with the aim of producing high-quality growing media and also having these checked. Jan made a major contribution to this and wanted to make this initiative a success. For his efforts, Jan was highly appreciated by colleagues, partly because he let the general interest prevail. Jan was very active in the establishment of the VPN and RHP. He also held board positions in both organisations.

Ad Hidding

Ad Hidding was best known in the substrate sector for his role as chairman of the Technical Committee of RHP. Ad held this position for more than 34 years! In 1967 he was asked to chair the Technical Committee. At that time he worked for the government as a consultant for soil issues in horticulture, and later as director of the IKC (Knowledge Center for agriculture and horticulture). The Technical Committee then drew up guidelines for potting soil companies. Hidding was known for his broad knowledge and insight. Research results from the research stations were translated by him and other committee members into

guidelines and later on RHP standards. This approach still forms the basis of RHP. He combined his work with visiting potting soil companies, which he liked to do and with which he could occasionally escape his office work in Wageningen. These companies were looking forward to the annual visit that Hidding paid in his position of chairman of the TC. He was seen as an authority, but he himself had little interest in this status. His high-level contacts within the government ensured that the potting soil sector was not unknown there. In this circuit the potting soil sector was also called “the hobby of Hidding”. From 1980 to 1992, Hidding presided over the Substrates Working Group of the International Society for Horticultural Science. Hidding was also a gifted speaker and knew how to mix serious subjects with his humour into beautiful presentations. 

Gerrit Boertje

Gerrit Boertje started his career in 1958 at the “Proefstation” (research station) in Naaldwijk as a researcher. In 1961 Gerrit became responsible for research in substrates. This was at a time when practice lacked knowledge and demanded it. Gerrit carried out many growth tests to get a grip on, especially, chemical aspects. In the early years, this was truly pioneering work. Much of the knowledge built up then, still forms part of the current basis. Years later, the physical aspects also got more attention. Gerrit developed himself as a peat and potting soil expert and gained a lot of respect at home and abroad. His knowledge was eagerly used in the “Regeling HandelsPotgronden”, which was co-created by the “Proefstation” (research station) in Naaldwijk (The Netherlands) and which was the predecessor of the current RHP. In 1975 Gerrit was entrusted with the secretariat of

the Technical Commission of this scheme. In the period from 1975 to 1986, Gerrit and a colleague became responsible for monitoring the scheme. For this he regularly visited the potting soil companies in the Netherlands, but also the locations of the raw material abroad. In 1987 Gerrit became technical director at a Dutch potting soil company. In addition to his role as a TC member, Gerrit held various other board positions in the sector. Gerrit was very serious and an example of a very honest person. Gerrit continued to be interested in the sector until long after his retirement. He knew how to assess new developments well and always asked the right questions.


Sources: Marco Zevenhoven and ‘Chronicle of 50 years of Potting Soil’

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