All our mother stocks are produced and housed in four different levels from A to D. The plants are all built from Elite material.
A high standard of cleanliness is maintained at all levels including the regular sterilization of all tools and utensils. The entire stock is checked regularly for viruses.

 Level A
This is the highest level and contains only Naktuinbouw SEE certified material. Varieties at this level are cultivated, produced and controlled by a designated, specially trained, non-smoking staff. These workers wear special clothing, shoes and gloves and use disposable knives. Regular controls are carried out by the PPIS and all the varieties can be supplied with a signed "Special Quality" certificate.



 Level B
All mother plants are from in-vitro Elite material. Production and regulations at this level are the same as in level A, however the material is not supplied with a "Special Quality" certificate.



 Level C
The foundation stock is taken from Cohens´ Bank of in-vitro material early in the year. All varieties are checked to be true-to-type and free from viruses.  From this foundation stock we produce Elite cuttings for the building of mother plants. Production is done by staff who wear gloves and robes and use tools that are sterilized before the production.




 Level D
After checking that the current stock is true-to-type and free from principal viruses, cuttings are taken to produce mother stock for the season to come. Production procedures and hygiene are similar to those of level C.