AbstractMany state highway departments in the USA must use native plants for revegetating roadsides. We conducted two field studies in West Virginia to assess native plant establishment under two different conditions. On newly‐constructed sites, native species were seeded alone or combined with non‐native species. On older roadsides, native species were seeded in disturbed existing vegetation. In the first study, we used four seed mixtures comprised of seeds of native and non‐native species, and two N‐P‐K fertilizer treatments at three newly‐constructed sites. Native, warm‐season grasses were slow to establish and only contributed 25 per cent cover in some plots after three years. Indiangrass (Sorghastrum nutans [L.] Nash), big bluestem (Andropogon gerardii Vitman), Brown‐Eyed Susan (Rudbeckia triloba L.), and wild senna (Cassia hebecarpa Fernald) were the only seeded native species found. Fertilizer at 150 kg ha−1 of 10‐20‐10 showed little influence on increasing plant cover. In the second study, we disturbed three different‐aged established stands of vegetation composed of tall fescue (Festuca arundinacea Screb.) and crownvetch (Coronilla varia L.) by mowing, herbicide, or tillage, and native plants were seeded with and without fertilizer. Native cover was <10 per cent in all plots during the first year, but greatly increased by the second year to as much as 45 per cent in tilled plots, indicating that disturbance was necessary for natives to become important contributors within 2 years. Only switchgrass (Panicum virgatum L.), little bluestem (Andropogon scoparius Vitman), partridge pea (Chamaecrista fasciculate Michx.), and Brown‐Eyed Susan were observed in plots. Fertilizer at 300 kg ha−1 of 10‐20‐10 did not increase native plant cover on these sites. Based on our results, introducing or increasing the cover of native species along roadsides requires (1) reducing competition from non‐native species, and (2) longer time periods for these slower‐establishing species to be observed. Copyright © 2008 John Wiley & Sons, Ltd.