Technical Abstract: Peat and perlite have served as industry standards in greenhouse substrates for over 50 years. Expanded perlite has long been used as an amendment in container mediums because of its ability to add air space to container substrates without adding to bulk density or affecting substrate pH and EC. However, due to increased restrictions on the harvesting of peat, as well as fluctuations in fuel prices necessary for shipping, the future availability of peat is a largely unknown factor in greenhouse production. Additionally, growers consider perlite to be a general nuisance due to the lung and eye irritation problems. These studies evaluated three possible substrate alternatives for use in greenhouse products, including fresh sweetgum (SG), hickory (H), and eastern redcedar (RC). Three greenhouse annual crops (petunia, impatiens, and vinca) were planted in varying ratios of these three wood species mixed with peat. Plants grown with SG and H as amendments did not perform as well as a traditional peat:perlite mix with respect to flower number, growth indices, SPAD values, and PDW. However, plants grown in RC tended to be equivalent to those grown in a traditional mix. Data showed that 2 greenhouse producers could amend their standard greenhouse substrate with up to 50% eastern redcedar with little to no differences in plant growth and overall aesthetic quality.