Drip irrigation with mineral water bottle is an easy way of watering plants. No cost involved in making this. No power or piping required for supplying water. It is very easy to make. Take an empty mineral water bottle. Then make 4 or 5 small holes
With summer just around the corner, consider automatic plant watering tools like these Aqua Spikes to save water in your garden. Aqua Spikes are designed to fit onto recycled soda bottles, and disperse water only when your plants need it!