PURPOSE: To provide system designed to efficiently grow plants without suspending the circulation of a nutritive liquor to raising beds and without the need for preparing additional tanks.
CONSTITUTION: The electrical conductivity of a nutritive liquor 8 to be used for plant raising is determined by an electrical conductivity meter 12; when the resultant electrical conductivity value is out of a specified range, an acid- alkali feeder 3, liquid fertilizer feeder 9 and water feeder 4 are selectively actuated respectively for a specified time so that the electrical conductivity value fall within the specified range through a controller 2, and concurrently, electrical conductivity control is performed to check its value at every specified time so that such value does not get out of the specified range; a nutritive liquor is replenished under the above actions.