There is an ever-increasing demand for sand to support projects like beach nourishment and dune restoration, but dredging and mining sand causes environmental damage. Demonstrating the environmental and ecological compatibility of crushed and ground glass known as cullet to support coastal restoration projects could simultaneously divert waste from landfills and decrease the need to mine or dredge sand. Here we present results from the first field-based experiment to assess how cullet performs as a supplementary sediment source and as a medium for plant growth in a coastal sand dune. American beachgrass, a plant commonly used in dune restoration, did not thrive during a growing season (May to August 2024) when planted in 100% cullet, but it grew well in on-site dune sand, as well as in a 90% sand 10% cullet mix. Laboratory-based incubation experiments showed that cullet is chemically reactive when exposed to solutions of high ionic strength (e.g. seawater), wherein the highest reaction rates occurred among the finest cullet grain sizes. Granulometry and geochemical data showed that while raw, sand-sized cullet is physically representative of natural sand (in grain size and shape), it varies substantially in chemical composition. Future work is required to determine the underlying cause of plant mortality when grown in cullet in saline environments. Small-scale, field-based experiments are recommended in advance of broad implementation of cullet in restoration projects to catch any potential unexpected environmental consequences.