This Is AuburnElectronic Theses and Dissertations

Evaluation of Eastern Red Cedar as a Substrate Component for Container Plant Production


Peat moss, perlite and pine bark, being readily available and relatively inexpensive, have been the most popular substrate components of greenhouse and container nursery production for the past forty to fifty years. Increasing demand for peat has resulted in economic and environmental concerns; while shortages have also been noted in previous years due to severe weather conditions. Perlite manufacturing and handling concerns have developed from its dust, considered to be an eye and lung irritant. Increasing energy cost has led to the use of pine bark as an alternative resource of clean fuels. This increasing demand for pine bark coincides with the slowly declining timber industry. These, and other factors have led to an increased need for locally available materials as alternative substrate components. Research evaluating high wood fiber substrates to grow plants has been shown to have positive potential when minimal adjustments are made to greenhouse fertilization and irrigation practices. In previous studies, plants grown in up to 50% fresh cut eastern red cedar had little to no difference when compared to plants in a grower’s standard. In multiple studies, eastern red cedar was evaluated as a potential substrate in greenhouse annual production. Red cedar is a coniferous species native to east and central North America, primarily east of the Rocky Mountains growing between 12.2-15.2 m (40-50 ft) tall, and reaching spreads of 2.4-6.1 m (8-20 ft). It has become known as a “weed species”, indicating cedar may have potential to be an economical and viable amendment in standard greenhouse substrates. In the first study, processed eastern red cedar (Juniperus virginiana) (RC) was evaluated as an alternative substrate in the greenhouse production of four annual species (petunia, vinca, begonia, and celosia). Three screen sizes of RC were used including 0.6cm (0.25in), 1.0cm (0.375in), and 1.3cm (0.50in). Plants were grown in either 25% or 50% RC mixed with a peat moss:perlite substrate. Plant growth was similar for two of the four species grown in 50% cedar at 1/4 in. screen size; all screen sizes were similar to the control treatment of peat moss and perlite grown in 25% RC for all species. The next study evaluated locally grown RC as a potential alternative to pine bark in the nursery production of 10 ornamental species. Plant growth for 7 of the species grown in 100% RC performed as well as plants grown in the pine bark control treatment. Species that have lower pH requirements did not perform as well in substrates amended with high percentages of cedar. Premier blueberry did not grow well in cedar above 40%. Formosa azalea and Sargents juniper growth was comparable to pine bark in up to 80% cedar. This data concludes that cedar has potential as an amendment to pine bark in nursery production. In the last study snapdragons grown in up to 75% RC with a 2.37 kg•m-3 fertilizer rate were comparable to those grown in 2.37 kg•m-3 (4.0lbs∙yd-3) 100% peat substrate. Pansies grown in up to 50% RC with 2.37 kg•m-3 (4.0lbs∙yd-3) of fertilizer were similar to those grown in 2.37 kg•m-3 (4.0lbs∙yd-3) 100% peat moss. Petunia growth was similar for all substrates with up to 100% RC when amended with 1.19 kg•m-3 (2.0lbs∙yd-3) of fertilizer. In conclusion, data shows eastern red cedar has potential as an alternative to peat moss amended up to 50% with the addition of fertilizer. These studies have shown that eastern red cedar is a source of locally available substrate that is economical and sustainable.