Gardening Methods

how much water is saved by watering a garden at night compared to during the day, I’m after actual figures.

I don’t know that you ’save’ any water at all. If you water for a certain amount of time, you will use the same amount.
If you water until the ground is really wet, you will still use about the same amount.
The difference is going to be how fast the water evaporates due to the surface temperature of the soil. This will determine how much gets to the roots for the plant to absorb.

I don’t think anyone has actual figures or has ever done a test on this. I would guess that it takes twice as much watering during the day to give the roots the same amount of available water, but it depends on the soil type, soil temperature, relative humidity, and depth of the roots.

building a self watering container