It depends on whose knowledge it is. Skill that any seasoned grower could bring is general; knowledge of the company's own propagation protocol, developed and refined inside the organization, can be specialized. The petition must make that distinction on evidence, not adjectives.
The test is about the company's methods, not the employee's talent
L-1B does not reward excellence in a trade; it recognizes knowledge that is tied to the petitioning organization. The regulation defines specialized knowledge as special knowledge of the company's product, service, research, equipment, techniques, management or other interests, or an advanced level of knowledge of the company's processes and procedures. A grower who knows how to manage humidity, light and nutrients in general terms holds knowledge the U.S. affiliate could hire locally. A grower who developed the company's own climate-control thresholds, its substrate recipe and the sequence it uses to move plugs from germination to finishing holds knowledge that exists only inside the company. USCIS looks for indicators such as whether the knowledge is proprietary, how many others in the organization hold it, how it was gained and whether it can readily be transferred to another worker. Petitions that rely on words like unique and invaluable without those facts are routinely refused.
Hypothetical example: A manufacturer of commercial dishwasher racks wants to transfer the employee who devised its internal load-mapping method. The first review asks for the method itself, its revision history, the number of employees who can use it and the U.S. task that requires it. The decisive record is not a supervisor’s praise; it is the controlled material showing that the method belongs to the company and is not ordinary factory skill. If the affiliate merely needs an experienced production worker, the case should not be described as specialized knowledge. The employer must also establish the qualifying corporate relationship and the required year of employment abroad.