Abstract: A selected number of troughs containing small plants therein are placed in a parallel relation with each other at one end of a soilless growth chamber. Tubular screw sections having helical grooves therein are employed for advancing the troughs from the loading end of the chamber to the unloading end thereof, the helical or screw pitch being considerably greater at the unloading or harvesting end in order to accommodate for the increased size of the plants as they reach maturity. In other words, the pitch of the helix is correlated with the rate at which the plants mature. Tubular screw sections having different pitches can be substituted when the growth rate differs from one species to another.

Abstract: A selected number of troughs containing small plants therein are placed in a parallel relation with each other at one end of a soilless growth chamber. Tubular screw sections having helical grooves therein are employed for advancing the troughs from the loading end of the chamber to the unloading end thereof, the helical or screw pitch being considerably greater at the unloading or harvesting end in order to accommodate for the increased size of the plants as they reach maturity. In other words, the pitch of the helix is correlated with the rate at which the plants mature. Tubular screw sections having different pitches can be substituted when the growth rate differs from one species to another.

Abstract: An apparatus for intermittently pushing a plurality of aligned carts along a predetermined path. The apparatus includes a pair of oscillating pusher bars having a plurality of aligned lugs thereon, which engage a portion of the undersurface of the carts and push them forward as the bars move in a forward direction. As the pusher bars move in the opposite direction, the lugs disengage from the cart, so as to permit the cart to remain stationary.