Our breeding department has a number of exceptional varieties to its name. Sometimes specific varietal characteristics are desirable. For instance the mildew resistant varieties and the West-European pink onion with the quality of the yellow Rijnsburger. There is a rising demand for specific properties in the Allium assortment. An often repeated request from the market is for varieties with resistance to common diseases such as Fusarium and Pink Root. We are working on finding a solution.


Long term

Our operations are characterised by the long term prospects. Developing a new variety represents a massive investment - both in terms of time and money. We reckon on a period of ten years and an investment equally hundreds of thousands of euros to create a new variety. The conditions for breeding varieties must be optimal in every respect. We create the perfect conditions for breeding in our greenhouses - which cover a total of 5 hectares- using the latest equipment and IT applications.

Trial fields

Together with Bejo we work and look after our trial fields. These plots are situated in the length zones that our onions can be cultivated in. This allows us to test and develop the varieties further under the widely differing conditions in the regions for which they have been developed. We have trial fields in various parts of the world, all with widely different day lengths.


The researchers at Bejo are specialised in resistance breeding, tissue culture, cell biology, DNA marker technology and research into health-beneficial nutritional contents.

200 varieties

Following the inclusion of the first onion variety – the Grobol - in the Dutch Variety List, it has been joined by countless other cultivars and varieties. We started with just onions, today we also focus on shallots and garlic. The range of varieties we offer is comprehensive, so that growers all over the world can choose varieties developed by De Groot en Slot. We have proven our capacity to develop varieties that are suitable for a wide diversity of regions, match the requirements of growers, the needs of the markets and the particular tastes of consumers. In addition, we offer a wide range of organic seed onions. This has made us into what we are today: the most specialised Allium breeding company in the world.