A crop production system for controlled environment agriculture, comprising: one or more grow lines, each of the one or more grow lines comprising a grow conveyance mechanism and a tower shuttle system; and a plurality of grow towers, each of the plurality of grow towers vertically attached to, and moveable along, a respective one of the one or more grow lines; wherein each grow conveyance mechanism comprises: a common beam having a cam channel disposed in a channel of the respective grow line the channel extending in a direction parallel to the grow line; an actuator attached to the common beam, wherein the actuator is operative to move the common beam along the channel in a forward stroke and a back stroke; and the common beam having a plurality of cam members pivotally attached at select positions along the cam channel of the common beam, wherein each cam member is mounted to limit rotation of the cam member during the forward stroke causing the cam member to engage and push a first grow tower forward in a first direction during the forward stroke and to allow the cam member to slide over a second grow tower during the back stroke; wherein the select positions of the plurality of cam members are each configured such that in a forward stroke a respective cam member engages a first grow tower during the forward stroke and ratchets over a second grow tower adjacent to the first tower during the back stroke; and wherein each tower shuttle system comprises a track mounted proximal to and extending parallel to the grow line; a carriage attached to the track; an actuator configured to cause the carriage to slide along the track; and an engagement member attached to the carriage and configured to releasably engage a grow tower; and a control system operative to cause the engagement member to engage the grow tower at a load position and cause the carriage to slide the grow tower to a select position along the grow line. one or more grow lines, each of the one or more grow lines comprising a grow conveyance mechanism and a tower shuttle system; and a plurality of grow towers, each of the plurality of grow towers vertically attached to, and moveable along, a respective one of the one or more grow lines; wherein each grow conveyance mechanism comprises: a common beam having a cam channel disposed in a channel of the respective grow line the channel extending in a direction parallel to the grow line; an actuator attached to the common beam, wherein the actuator is operative to move the common beam along the channel in a forward stroke and a back stroke; and the common beam having a plurality of cam members pivotally attached at select positions along the cam channel of the common beam, wherein each cam member is mounted to limit rotation of the cam member during the forward stroke causing the cam member to engage and push a first grow tower forward in a first direction during the forward stroke and to allow the cam member to slide over a second grow tower during the back stroke; wherein the select positions of the plurality of cam members are each configured such that in a forward stroke a respective cam member engages a first grow tower during the forward stroke and ratchets over a second grow tower adjacent to the first tower during the back stroke; and wherein each tower shuttle system comprises a track mounted proximal to and extending parallel to the grow line; a carriage attached to the track; an actuator configured to cause the carriage to slide along the track; and an engagement member attached to the carriage and configured to releasably engage a grow tower; and a control system operative to cause the engagement member to engage the grow tower at a load position and cause the carriage to slide the grow tower to a select position along the grow line. a common beam having a cam channel disposed in a channel of the respective grow line the channel extending in a direction parallel to the grow line; an actuator attached to the common beam, wherein the actuator is operative to move the common beam along the channel in a forward stroke and a back stroke; and the common beam having a plurality of cam members pivotally attached at select positions along the cam channel of the common beam, wherein each cam member is mounted to limit rotation of the cam member during the forward stroke causing the cam member to engage and push a first grow tower forward in a first direction during the forward stroke and to allow the cam member to slide over a second grow tower during the back stroke; wherein the select positions of the plurality of cam members are each configured such that in a forward stroke a respective cam member engages a first grow tower during the forward stroke and ratchets over a second grow tower adjacent to the first tower during the back stroke; and wherein each tower shuttle system comprises a track mounted proximal to and extending parallel to the grow line; a carriage attached to the track; an actuator configured to cause the carriage to slide along the track; and an engagement member attached to the carriage and configured to releasably engage a grow tower; and a control system operative to cause the engagement member to engage the grow tower at a load position and cause the carriage to slide the grow tower to a select position along the grow line.