“Knowledge of soil organisms is key in ideal potting mixture”

Otwin van Geest of VG Orchids, De Lier, the Netherlands:
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“Knowledge of soil organisms is key in ideal potting mixture”

Bark, the main ingredient of orchid substrates, is steamed at high temperatures. This kills off all the impurities and pathogens. But unfortunately it also spells the end of a lot of good things. What remains is a sterile medium – and try growing a resilient crop in that. After all, a healthy plant starts with a healthy root package. So VG Orchids does the logical thing: it has soil organisms added to its substrate.

Adding additives to substrate restores the natural symbioses and creates a healthy environment for the roots. This brings Phalaenopsis growers one step closer to the ideal potting compost.

Over the years, family business VG Orchids, which has two branches in the Dutch town of De Lier and includes the innovative brand VG Colours, has grown from 2,000 m2 of cut Phalaenopsis to 12 hectares of pot orchids. The plants are supplied in 6 and 12 cm pots. Cultivation manager Otwin van Geest has been working exclusively with the new Infigo substrate from BVB Substrates at their main branch for a year now. In addition to bark and pH buffering peat, this mixture contains several additives to ensure stable soil life and good resilience. An important part of this is the microorganism Trichoderma harzianum T-22 (Trianum) from Koppert’s NatuGro package.

Reducing chemicals

A good substrate forms the basis for healthy roots and a resilient plant. But the way in which this knowledge is used varies from grower to grower. For VG Orchids, the choices they make in this area are key to successful and sustainable Phalaenopsis cultivation.

The company therefore follows developments closely, working with their substrate supplier as a regular partner. They too are constantly pushing the boundaries: innovation is a vision both companies share. Van Geest: “We want to progress, and as long as we can see improvements happening, we’re happy to sit down with the customer and come up with solutions. Our ultimate goal is not the mixture per se but rather to reduce our use of chemicals. Crop protection products often stunt plant growth. Besides, as a grower you want to cut down on the amount of chemicals you use. So we are looking for other ways to keep the crop healthy. A resilient plant can solve a lot of problems itself, so we’re fully behind this development.”

Natural resilience

The cultivation manager likes to make the comparison with people. “If a person is regularly exposed to good and bad bacteria in their immediate living environment, they develop a healthy immune system. Then, if they are exposed to increased levels of a pathogen, they will be less likely to fall ill than someone growing up in a sterile environment. And so it is with plants too.”

That is why the environment around the roots is so important, he believes. “There must be enough oxygen and soil organisms in the pot to ensure optimum uptake of important elements and nutrients. And when you can no longer be certain that that is the case – if the substrate is sterile – you have to add those components artificially. In our current mixture, for example, the peat helps the organic elements bind together well and Trianum protects the roots against harmful fungi.”

Thoroughly trialled

The search for the ideal potting compost is a continuous process in which new information and knowledge is constantly being incorporated into solutions. VG Orchids facilitates a think tank that meets regularly to exchange experiences. It is attended by the cultivation manager, a specialist from Aqua Terra Nova, a microbiologist and cultivation specialist from BVB Substrates, a specialist from Koppert and adviser Peter Klapwijk.

“Following these meetings, which we hold once every ten weeks, we usually set up five substrate trials here,” says Van Geest. “Important aspects we test are the proportions of bark, coir, sphagnum and peat, with and without various additives. Previous cultivation trials have shown that the Infigo mixture is best for our company in terms of crop steering. As a result of the research conducted by the think tank, further improvements have been made to this mixture in the form of plant strengthening additives. The results are positive. The pots are full of healthy roots and leaf surface has increased by 20 to 25 percent.”

Continuous measurement and refinement

This collaboration is also worth its weight in gold to the substrate supplier. Orchid specialist Robin Camphens: “We are an innovative company and we want to stay ahead. With this in mind, we recently hired a microbiologist. His expertise is very enlightening and gives a real boost to our work developing new potting compost mixtures. You only need to look at VG Orchids, where he advised on the successful additives for the substrate. Soon, when our new research centre with phytotrons comes into operation, we will be able to focus even more specifically on orchid solutions.”

Camphens’s colleague Richard Bremmer regularly visits the orchid company to monitor the trials. He also checks the performance of the “standard” substrate, of course, and takes soil samples for a complete chemical analysis once every six weeks. The peat in the mixture makes this research possible. Koppert also carries out plant sap, Trianum and soil nutrient web analyses. Once a week, the grower monitors growth in plant height and width and measures the pH and EC. The results are discussed, following which any necessary adjustments are made to the growing formula or new trials are set up. In short, it’s a continuous process of measurement and refinement.

Successful teamwork

The two partners hope to be able to observe more effects of the new substrate in the near future. Bremmer: “We expect a more resilient crop to lead to fewer losses. And of course the quality should be better too: a healthy plant branches better and produces lots of buds. I am gradually seeing an upward trend. Of course, resilience depends on several factors. Your crop protection strategy must be right, you must get your hygiene right – that sort of thing. But the main focus is still on the root environment, and our grower-specific potting compost mixture is an important step in this direction.”

Van Geest appreciates the supplier’s input. “Their knowledge is pure added value for us. We have every faith in their people and their product. The quality is consistent year round, and orchids appreciate that; inconsistency leads to stress and stunted growth. And as a grower, that’s something you want to prevent at all costs. A resilient plant can do so much more.”

Summary

The Dutch pot plant company VG Orchids has switched to a tailor-made substrate for Phalaenopsis. Standard potting composts are often too sterile and VG Orchids hopes to create a healthier climate for the roots with additives like peat and Trianum. A good mixture is the basis for a strong root package and, ultimately, a more resilient crop. This resilience should reduce stress and offers growers an opportunity to reduce their use of chemicals.

Text: Jojanneke Rodenburg.
Images: Studio G.J. Vlekke.

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