RNA folding in vivo is driven by a diverse set of interactions with cytoplasmic components. Of these interactions, the screening of negatively charged phosphates on the RNA backbone by cations is critical for folding to the native structure. Given their high intracellular concentrations, the positive charges of Mg2+ and putrescine (totaling 100mM and 60mM respectively) neutralize a large fraction of negative charges possessed by structured RNA. Using an experiment analogous to equilibrium dialysis we observe the competitive interactions of putrescine and Mg2+ in an RNA ion atmosphere for both native and intermediate states of RNAs. These interactions are related to a folding free energy landscape for three different RNAs. In the presence of Mg2+, putrescine is found to be either stabilizing or destabilizing depending on the fold of the RNA. RNAs that chelate Mg2+ become destabilized in the presence of putrescine while non-chelators become more stabilized by putrescine. For some RNA molecules putrescine has an apparent synergistic effect on excess Mg2+ while other RNAs show an antagonistic effect. These results can be attributed to a difference in the manner in which putrescine and Mg2+ populate the ion atmosphere and affect RNA conformation.