segments 44 are constructed of sheet plastic and may be flexible in order to form an arcuate configuration with the flanges being reversely formed and oriented at approximately 15 u00b0 in relation to the plane of the remainder of the panel 44 when in a flat condition with the assembly of the pipe 52 in relation to the flanges being by a longitudinal sliding movement and the assembly of the locking pipe 58 also being by a longitudinal sliding movement the panels may have a top length of just over 20 inches and extending through an arc of approximately 40 u00b0 with a radius of approximately 36 inches and the radius of the inner edge 48 may be approximately 26 inches to produce a vertical height of each tub of approximately 10 inches as indicated these dimensions may vary depending upon the plants to be grown and the quantity of soil or growth supporting medium 60 to be positioned in each tub 18 the pipes 52 and 58 as well as the panels 44 are preferably constructed of polyvinyl chloride with each tub including eight sections with the locking pipes 58 extending above the top edge 50 as at 62 for providing a support for vines to provide a more effective support for foliage which may result from the plants growing in the tubs the irrigation assembly 20 includes a vertically disposed supply pipe 64 oriented generally parallel to the retaining tubes 14 and spaced.