A retaining wall system configured to substantially stabilize a slope formed from earthen material, the retaining wall system comprising: a stabilizing wall comprising a plurality of stacked courses formed from one or more substantially horizontally-extending mesh tubes (4200, 4202), each tube substantially filled with a plant growing medium; a plurality of modular tube retainers (1100, 4100, 4102) collectively configured to substantially resist tipping and bowing of an approximately planar major face of the stabilizing wall, the slope located distal to the major face; and wherein: each filled mesh tube has a substantially oval longitudinal cross-section; each tube retainer comprises a substantially open-backed, pre-bent interlocked wire mesh element that defines a substantially planar base portion that is integrally connected to a substantially planar face portion, the base portion configured to be in direct contact with and to substantially support a bottom of a tube from the one or more substantially horizontally-extending mesh tubes, the face portion configured to be in direct contact with a front of that tube, the base portion configured to extend substantially horizontally from the face portion into the earthen material for a distance that greater than a longitudinal cross-section dimension of the tube; each tube retainer defines a plurality of retainer apertures that are configured to substantially allow plant roots and the earthen material to pass substantially vertically therethrough in a zone within the retaining wall system that is distal to the major face; each tube retainer is substantially stabilized by at least one reinforcement strap that extends through a portion of the earthen material but does not loop or wrap around a corresponding tube; each reinforcement strap loops through an aperture bordered by a substantially horizontally-extending handle of a corresponding tube retainer; each handle has a diameter of at least 0.5 inches. a stabilizing wall comprising a plurality of stacked courses formed from one or more substantially horizontally-extending mesh tubes (4200, 4202), each tube substantially filled with a plant growing medium; a plurality of modular tube retainers (1100, 4100, 4102) collectively configured to substantially resist tipping and bowing of an approximately planar major face of the stabilizing wall, the slope located distal to the major face; and wherein: each filled mesh tube has a substantially oval longitudinal cross-section; each tube retainer comprises a substantially open-backed, pre-bent interlocked wire mesh element that defines a substantially planar base portion that is integrally connected to a substantially planar face portion, the base portion configured to be in direct contact with and to substantially support a bottom of a tube from the one or more substantially horizontally-extending mesh tubes, the face portion configured to be in direct contact with a front of that tube, the base portion configured to extend substantially horizontally from the face portion into the earthen material for a distance that greater than a longitudinal cross-section dimension of the tube; each tube retainer defines a plurality of retainer apertures that are configured to substantially allow plant roots and the earthen material to pass substantially vertically therethrough in a zone within the retaining wall system that is distal to the major face; each tube retainer is substantially stabilized by at least one reinforcement strap that extends through a portion of the earthen material but does not loop or wrap around a corresponding tube; each reinforcement strap loops through an aperture bordered by a substantially horizontally-extending handle of a corresponding tube retainer; each handle has a diameter of at least 0.5 inches. each filled mesh tube has a substantially oval longitudinal cross-section; each tube retainer comprises a substantially open-backed, pre-bent interlocked wire mesh element that defines a substantially planar base portion that is integrally connected to a substantially planar face portion, the base portion configured to be in direct contact with and to substantially support a bottom of a tube from the one or more substantially horizontally-extending mesh tubes, the face portion configured to be in direct contact with a front of that tube, the base portion configured to extend substantially horizontally from the face portion into the earthen material for a distance that greater than a longitudinal cross-section dimension of the tube; each tube retainer defines a plurality of retainer apertures that are configured to substantially allow plant roots and the earthen material to pass substantially vertically therethrough in a zone within the retaining wall system that is distal to the major face; each tube retainer is substantially stabilized by at least one reinforcement strap that extends through a portion of the earthen material but does not loop or wrap around a corresponding tube; each reinforcement strap loops through an aperture bordered by a substantially horizontally-extending handle of a corresponding tube retainer; each handle has a diameter of at least 0.5 inches.