Organic matter decay in salt marsh soils is not well understood. We used the Tea Bag Index, a standardized litter approach, to test how decay changes with soil depth, elevation, and time. The index overestimated decay, but one component, rooibos tea, produced comparable rates to natural litter. We found that decay was higher at shallower depths and lower marsh elevations, suggesting that hydrological setting may be a particularly important control on organic matter loss.