Planting Rings are available in 16 20 and 24-inch diameters (outside) and are the prefect product for water conscientious gardeners and landscapers who want a no-fuss perfectly round border around trees shrubs roses or vegetables. Unlike most edging Planting Rings do not require bending staking or tools to create a round border. Planting Rings are non-eroding watering basins that retain water and fertilizer until they can funnel to the deep root zone where it is needed most. The patented V-Groove anchors the Planting Ring into the soil so it stays securely in place. The naturally UV resistant 100 recycled polypropylene protects trunks from weed whackers and provides a clean border between grass trees and shrubs. Planting Rings reduce surface evaporation cut down on invasive weed growth and prevent hillside erosion. Planting Rings can also be adapted to couple irrigation systems.Planting Rings Sizes are 16 diameter for 1 gal. plants (holds 2 gal.)20 diameter for 5 gal. plants (holds 3 gal.)24 diameter for 15 gal. plants (holds 5 gal.) Easy to install Eliminates surface evaporation Cuts down on invasive weed growth Prevents hillside erosion Funnels water to the deep root zone Provides protection from mowers and weed whackers Can be adapted to couple with drip irrigation