Objective: This study aimed to clarify which older adults benefit most from a control-enhancing intervention; in particular, whether cognitive functioning or locus of control might moderate the benefit derived.

Methods: Nursing home residents were randomly assigned to two conditions: (1) a control-enhanced condition that provided the option of caring for a plant (n = 10), and (2) a comparison condition that monitored any change under the standard of care (n = 10). Comparison group participants were subsequently offered the intervention, which led to a total of 17 intervention participants.

Results: Cognitive function and locus of control were found to significantly moderate the effects of the control-enhancing intervention on residents' perceived health competency, but not depression or life satisfaction.

Significance of results: Interventions for nursing home residents could be tailored to fit specific needs. Screening for cognitive function and locus of control may help predict who is likely to benefit from control-enhancing interventions.