Technical Abstract: Shortages of peat for use in the greenhouse industry are already a problem, and greenhouse producers are faced with continued shortages, as well as increases in its price. In this study, three hardwood alternatives (sweetgum, hickory or eastern redcedar) were evaluated as amendments to a standard peat/perlite mix. These hardwood species are currently valued as ‘trash trees’ to the industry that could potentially be employed as economical and viable amendments, or even alternatives, in standard greenhouse substrates. The data indicated that Plants grown with sweetgum or Hickory treatments differed significantly from the growers standard and are not recommended as amendments for annual plant production with current greenhouse practices. However, greenhouse producers could amend their standard greenhouse substrate with up to 50% eastern redcedar with little to no differences in plant growth or flowering.