Watering with plastic watering cans is an effective way to water a small garden, indoor plants and outdoor potted plants. Plastic watering cans are usually more economical than metal watering cans, however they are more likely to crack and break. They therefore need replacing more often. If you have a plastic watering can, there are some tricks to making the most out of your hand watering so you don't have to water as frequently.
Add mulch, such as wood chips, to your garden and potted plants to help retain water, especially since you are watering your plants by hand.
Bury coffee or similar cans into the soil next to your plants planted outdoors in the ground, especially plants with deep roots (e.g., tomatoes). Poke a couple holes in the bottoms first so the water will drain out the bottom. Use a sharp knife (e.g., utility knife) or Phillips head screwdriver to make the holes.
Water outdoor plants in the morning hours when the air is coolest and the water will not evaporate as much.
Fill your plastic watering can with water. Leave about 2 to 3 inches of space at the top of the watering can so you do not spill it as you move it.
Water slowly around the base and under the canopy (leaves) of your plants with about 1 to 2 inches of water. Water potted plants until the water drains out the drainage holes and stop. Also, if applicable, fill the buried cans with water to help water the deeper tap roots.
Put your plastic watering cans away, or in an area that does not receive high winds. Plastic watering cans are light and will blow around in the wind. Also, plastic fades in the sun, so keep it out of the sunlight if you do not want it to fade.