Local ecological knowledge of culturally important plants informed food choices by Indigenous peoples across North America. Recovery of such knowledge through ecological and genetic studies of contemporary populations increases understanding of variation in seasonal availability and economic value, potentially enhancing interpretation of the archaeobotanical record. We compared habitat, seed yield, and nutritional value of seed in up to ten wild populations of net-seed goosefoot (Chenopodium berlandieri) from four survey regions in Manitoba, North Dakota, Missouri, and Ohio with evidence of pre-contact cultivation and domestication of C. berlandieri. We assessed cultivation impacts and variation in seasonal timing by growing seed from three Manitoban populations in two common gardens. Population density, plant size, and seed yield increased sixfold from north (Manitoba) to south (Ohio) in wild populations, with genetic differences between Manitoban populations remaining evident in gardens. However, cultivation (e.g., watering, weeding) in well-worked soil extended timing of seed harvest and increased seed yield beyond the range of wild populations. Nutritional profiles from five populations were similar across the survey regions but differed from domesticated quinoa in their higher fiber and slightly lower energy content. Our results suggest that both plasticity and genetic factors influence productivity of C. berlandieri populations as a seed source. Genetic variation in seasonal timing would have provided choice between populations and flexibility in incorporating C. berlandieri into a seasonal subsistence strategy. Simple cultivation techniques would have substantially increased yield, thereby enhancing reliability and economic returns.