Water until established, how does one know it is established?

[ericmark]

So I have made a box to take plants to hide the wood used to build some steps, around 8" deep, around 250 litres of compost to fill the box, so wife goes out and gets the plants, which are planted out, same day.

This was Tuesday, and clearly been hot since, so watered every day, and the water has been absorbed by the soil/compost, the drive has remained dry even when full watering can of water added, hose pipe first day.

I will clearly have to continue in this dry weather to water them, but at what point can I say they are established and I can stop watering every day?

 

[StephenStephen]

If you've not lined the sides with plastic, I would urge you to do so - the water loss through the gaps in the wood will be making a huge difference.
Mulch the top of the soil with bark or well rotted manure, to slow down evaporation.

You really do need to be getting the water to the bottom of the soil, not the top. Otherwise the roots will grow up to the top of the soil where they're more vulnerable to drying out.
So either put in 2 or 3 downpipes or similar (cover them when not watering to prevent evaporation), or water the bed until you know it's reached the base (ie; water is running out of the bottom).

Watering little and often is a bad idea. You need to be watering fully and deeply, but less often.

If that was my new bed, I'd be putting on 4 or 5 cans of water every 3 days or so in this weather.

You'll start to see the plants turning their attention away from the roots and towards top growth after a few weeks - this tells you that the roots are established.

 

[ericmark]

Thank you, some good points, once we get rain water will be fed to the bottom, but from what you are saying should slowly increase the time between watering them.