This is a very cheap self watering solution. All you need is a plastic bottle with screw cap, a watering tray with high rims, a knife and water.
Make a square hole in the side of the bottle from the bottom and 1 to 2 centimeter high and wide. Make sure the hole isn't higher than the tray rims minus 0.5 centimeters. Otherwise the water will overflow the tray.
Fill bottle with water through the hole (with the cap on).
Put the plants on the tray.
Place the bottle standing on the tray so that the water runs out. It will only run out until the water blocks the hole.
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