Establishment of trees in the range as part of a silvopoultry system is considered to improve poultry welfare as well as provide wider environmental benefits. However one issue with these systems is a lack of understorey vegetation. This paper outlines the results of a trial on an organic poultry unit in southern England. The trial aimed to identify an understorey sward mixture able to establish and persist in a commercial poultry unit. Three sward mixtures (a standard grass and legume mix, a grass only mix, and a diverse sward mix) were sown in replicated 15 year old mixed broadleaf plots and compared with a natural regeneration control. Chickens were excluded for the first 3 months to allow sward establishment and then introduced for a 6 week period at two densities. Growth and establishment of the sward mixes along with the presence and abundance of unsown plants and unpalatable weeds was assessed. All mixtures established well under trees and didn’t show significant differences in cover after 6 weeks. Sward cover increased after 4 weeks suggesting minimum establishment period and higher weed suppression potential after this. Sowing any of the sward mixtures reduced the abundance of unpalatable weeds compared to the control. The commercially available standard sward mixture performed well compared to the other mixes, showing significantly higher biomass production by week six. Following the introduction of chickens, the sward mixtures survived only in the block with lower chicken pressure, measured by distance from house. Results from this trial demonstrate that establishing a sward under trees is possible but that the challenge is to maintain the sward in the presence of chickens. Excluding chickens initially to aid establishment and then optimising chicken pressure appears to be the key to maintaining a sward.