Weed control with TopControl

Weed control in pot and container cultivation is a challenge for many growers. Due to the limited application possibilities of pesticides, a lot of time must be spent on weeding weeds and moss during cultivation and delivery work.

Nowadays there are more and more different covering materials on the market to protect against weeds and moss. Which covering material is chosen depends, among other things, on the cultivation system, the method of fertilisation and the customer's wishes. In 2019, the Delphy Tree Nursery Research Center set up a trial with eight different types of covering materials. The TopControl covering material from Van der Knaap was also included.


TopControl consists of pressed flax grains that fall apart after contact with water and form a covering layer. After a single irrigation, the compressed pellets take on their original volume. The fibres interlock, creating a uniform covering layer. This layer remains intact, even if the plants topple over by wind. The material will darken after a few months. The TopControl layer is moisture- and air permeable and dries very quickly. Weed seeds have no chance to germinate, due to the rapid drying. There is also no chance for moss formation on the cultivation layer.

The trial

During the trial, various covering materials were applied immediately after potting according to the instructions for use of the manufacturer or supplier. Thuja were potted in March and grown in a lava container field until the finished product was available in November, equal to the situation in practice. The weeds that managed to root were regularly removed during cultivation to test the performance of the covering materials. The (fresh) weight and type were recorded.

Results / conclusion

Three observation rounds were conducted. This showed that all covering materials are very effective and the results showed no significant differences between the tested materials. On TopControl, the researchers reported a stable product with a beautiful natural appearance. “It sits nicely on the pot and the material darkens over time. Because it is delivered in dried and pressed form, a large surface can be covered with a relatively small volume”, says the Nursery Research Center.

More information

TopControl is suitable for virtually all crops and can be used in various growing systems. It is easy to process, both mechanically and manually, and is easy to apply even after potting. In addition, it reduces evaporation, which makes it possible to save on irrigation water. For more information, please contact one of our cultivation specialists at sales@vanderknaap.info or 0174-525050.

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