Application of seed-containing plant material is a successful technique to transfer plant species onto restoration sites. However, this restoration method is almost confined to semi-natural open habitats. Plant material mown from understory and edge vegetation of a secondary Japanese black pine (Pinus thunbergii Parlat.) forest was taken in three different dates (September, October and November) to assess the ability of propagule recruitment in such closed habitats. Both the number of seed-produced species and the amount of seed were small in September compared with those in October and November. This is due to the fact that most species were under early stage of their flowerings, suggesting that September is inappropriate for harvesting seeds from plant community in this study site. Although many grassland species were recorded in both understory vegetation and edge vegetation, the number of produced seeds was clearly smaller in understory vegetation for most of grassland species, demonstrating that understory vegetation was inappropriate for the seed-containing plant material, due largely to the shortage of photon flux density.