Gardman Large Water Saver for Large Garden Pots This large Water Saver garden pot insert helps capture and retain moisture for larger garden pots. FREE POSTAGE £9.49 This large water saver garden pot insert is ideal for saving water for larger garden pots. Flexible rim for a range of pot sizes from 25cm to 35cm. Catches water run-off and turns ordinary pots into self-watering pots. Reduces water and nutrient wastage.