<p>The trajectory of marsh development in created marshes is highly variable, with development of plant productivity, organic matter storage and nutrient cycling important for achieving restoration goals. The paradigm of slow development of biogeochemical processes was examined for nutrient and gas exchange in marshes created from materials dredged from the upper Chesapeake Bay. At Poplar Island, marshes created from fine-grained sediments benefit from high soil nutrient concentrations and rapid growth of high and low marsh plant species. Marsh development occurred over a number of years, with multiple individual wetland segments, or “cells”, providing a broad view of the pace of wetland development. Using flooded cores, the fluxes of O₂, N₂ and nutrients were determined under both dark and illuminated incubation conditions. The rapid development of edaphic algal productivity in marsh and creek environments produced surficial organic matter enrichments that accelerated nutrient cycling processes. Comparisons of young (&lt; 2 y) and old (5–7 y) wetland cells showed that overall rates of soil respiration, photosynthesis, and denitrification were similar, suggesting rapid development of biogeochemical cycles. Rates of marsh and creek denitrification averaged 11–14&#xa0;g N m^− 2 y^− 1, larger than most published rates in other wetland restoration projects. These data suggest that microbial denitrification occurs at high rates early in the development of the wetlands, likely a function of nutrient-enriched substrate and a marsh surface with minimal vertical drainage.</p>