I got the idea for this project from a post by ShirleyE who uses a small water bottle to water houseplants and seedlings. Thank you Shirley!
Mine is not an improvisation, more of a variation. It is ideal for containers a bit larger than those for most houseplants. There is a low, common wall between my neighbor's home and mine. I use this wall to grow many small plants, raising them in concrete mixing tubs.
I have three tubs of spinach seedlings. Some of them are so small, pouring water on them directly from a jug really disturbs them. I found a way to provide water more gently.
Use a clean plastic gallon jug. Make sure it has a screw on lid, not the snap on type. With hammer and a small nail, punch holes in the lid. You decide the number and size of the holes. Add one hole to the jug handle where it starts to curve into the neck. This vent hole will allow air to enter the jug as it is emptying. By covering or uncovering the hole, you can control the rate of water flow.
Fill the jug with water, screw on the cap, and water your tender seedlings to your little ol' heart's desire. Add a bit of fertilizer to the water, if needed, and do foliar and soil feeding at the same time.
Thanks to my long time friend and farmer neighbor for demonstrating the watering jug in use.