In order to study the organic wastes (tree bark, tea waste and rice hull) and a water fern "azolla" naturally grown in Gilan province, experiments were conducted in a randomized block with 4 replications and 12 treatments of different mixture for media using 6 plants of dwarf marigold cultivar " Golden Boy" as the experimenal unites. The mixture were planted to be used as a substitute for peat in ornamental planting and for other greenhouse culturing purposes. In the Department of Horticulture, College of Agriculture Tehran university and in autumn 1996. Tree bark, tea waste and rice hull were mixed with 0,25,75 and 100% azolla(by volum) and then were com posted in 1 cubic meter woody containers. After five month of composting, physical Properties as bulk and particle density, water and air volume percentage, water holding capacity, porosity, soilds and organic matter percentage, pH, carbon, nitrogen, phosphorus, potassium, and chemical properties such as EC, cation exchange
capacity and C/N ratio were measured. Control was a mixture of 50% peat and 50% perlite. Fresh and dry root and top weight of plants, plant height, number of lateral shoots and numher of opened flowers were all evaluated as the growth indices. The highest rate of growth was noted in plants grown in medium of 100% azolla and medium of 25% tree bark+ 75% azolla . Results indicated that under the present economical conditions tree bark and tea wastes composts were good substitute for peat in culturing of ornamental plants. Composted tree bark with %50 and %75 of azolla showed a notable reduction of C/N ratio and the compost produced was ranged "Standard" from the standpoint of C/N (C/N <35), while C/N ratio of tree bark could not be decreased down to standard level by 25% azolla.
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