A system (1,31,61,71,81) for determining at least one control parameter for at least one device (11-16, 41) controlling an environmental condition in a plant growing environment, said system (1,31,61,71,81) comprising: at least one communication interface (3,33,63,73,83); and at least one processor (5,35,65,75,85) configured to: - obtain one or more target values for said environmental condition, - use said at least one communication interface (3,33,63,73,83) to receive information relating to control of a further environmental condition in said plant growing environment, wherein said further environmental condition relates to a different physical property of the environment than said environmental condition, - determine, from said information, data which represent an anticipated influence of said control of said further environmental condition on said environmental condition, wherein said anticipated influence relates to a side-effect resulting from controlling said further environmental condition, which side-effect is anticipated to influence said environmental condition, - determine said at least one control parameter for said at least one device (11-16, 41) controlling said environmental condition based on said one or more target values and said data, and - output or store said at least one control parameter. at least one communication interface (3,33,63,73,83); and at least one processor (5,35,65,75,85) configured to: - obtain one or more target values for said environmental condition, - use said at least one communication interface (3,33,63,73,83) to receive information relating to control of a further environmental condition in said plant growing environment, wherein said further environmental condition relates to a different physical property of the environment than said environmental condition, - determine, from said information, data which represent an anticipated influence of said control of said further environmental condition on said environmental condition, wherein said anticipated influence relates to a side-effect resulting from controlling said further environmental condition, which side-effect is anticipated to influence said environmental condition, - determine said at least one control parameter for said at least one device (11-16, 41) controlling said environmental condition based on said one or more target values and said data, and - output or store said at least one control parameter. - obtain one or more target values for said environmental condition, - use said at least one communication interface (3,33,63,73,83) to receive information relating to control of a further environmental condition in said plant growing environment, wherein said further environmental condition relates to a different physical property of the environment than said environmental condition, - determine, from said information, data which represent an anticipated influence of said control of said further environmental condition on said environmental condition, wherein said anticipated influence relates to a side-effect resulting from controlling said further environmental condition, which side-effect is anticipated to influence said environmental condition, - determine said at least one control parameter for said at least one device (11-16, 41) controlling said environmental condition based on said one or more target values and said data, and - output or store said at least one control parameter.