Device for germ-free and microbiome controlled growth of plants

A device (1) for growing plants (18) under controlled microbe conditions comprising an upper compartment module (2) having a first cavity (8) and being adapted for housing above-ground parts of a plant (18), a lower compartment module (3) having a second cavity (12) and being adapted for housing below-ground parts of a plant (18), and a middle barrier module (4) arranged between the upper and lower compartment modules and adapted to house a seedling or a seed for germination within an internal third cavity (13). The middle barrier module (4) comprises a filling material (17) in which a seed or seedling may be positioned and fixed and which allows growth of said seed or seedling, said filling material (17) substantially isolating the first cavity (8) of the upper compartment module (2) from the second cavity (12) of the lower compartment module (3), such that the first cavity (8) and the second cavity (12) are not in any fluid communication with each other.