Plug production is an integral part of today's floriculture industry. However, if seedlings are held in plug flats for too long, they may not return to a normal growth rate after transplanting. Stunting may render plants unsuitable for sale. Common bedding plant and cut flower species were grown in 288-plug flats to determine how long plugs could be held in the flats and still regain a normal growth rate and desirable growth form after transplanting. Species surveyed included: Antirrhinum, Begonia, Brassica, Callistephus, Celosia, Consolida, Dianthus, Eustoma, Gazania, Helianthus, Impatiens, Lycopersicon, Matthiola, Tagetes, and Viola. Ten randomly selected plugs were transplanted to 15- or 17-cm pots every 1 or 2 weeks for 10 weeks, when root balls were sufficiently developed to hold together after removal from the flat. Overall plant height was recorded for all species every 1 or 2 weeks. Plant diameter was recorded every 2 weeks for Begonia, Celosia, Eustoma, Helianthus, Impatiens, Lycopersicon, and Tagetes. A plug was considered to be stunted if it died after transplanting or did not resume a normal growth rate. Species that exhibited stunting included Brassica, Callistephus, Celosia, Consolida, Dianthus, and Tagetes. For example, Consolida seedlings held in the plug flat for 7 weeks after optimal transplanting time were six times smaller than those that were transplanted at the optimal time. Several factors were investigated to determine how they affected the degree of stunting, including: light quality, root obstruction, nitrogen enrichment prior to transplanting, gibberellic acid addition prior to transplanting, teasing of the root ball prior to transplanting, and length of drainage column.