Hello Hechmo,

You'll need to moisten the soil volume from the planting containers plus a little surrounding soil as well. Keep in mind that one gallon of water moistens about 1 cubic foot of soil.

Your 36" box tree has about 27 cubic feet of container soil, so you'll need at least 27 gallons of water. The 24" box tree has about 8 cubic feet of soil to moisten - so at apply at least 8 gallons.

The frequency will depend on the time of year and when you planted. The schedule from page 14 of Landscape Watering by the Numbers recommends the following for plants installed in fall through spring.

Weeks 1 & 2 - water once every 3 - 4 days
Weeks 3 & 4 - water once every 6 - 7 days
Weeks 5 & 6 - water once every 7 - 10 days
Weeks 7 & 8 - water once every 10 - 14 days

By week 8 it will be the first of February and you can stay on the 10 - 14 day schedule until the end of that month or even mid March, depending on the weather. When temperatures begin creeping up, you'll need to increase the frequency gradually so by summer you are watering twice a week.

Here is a link that might be useful: Landscape Watering by the Numbers

Have no experience with Ash, but Jacarandas, once established, are extremely drought tolerant, and a fine choice for the VOTS. I water mine once per week through summer for 90 minutes/2gph emitter. I swap to a 1 gph emitter and water about every two weeks through winter, though they can survive (if not thrive) on far less.

Forgot to mention that you'll need to protect your Jacaranda on cold nights. They are very frost sensitive when young so wrapping the trunk and covering the tree (if possible) will insulate it.

Here is a link that might be useful: Frost Protection

Good to know, thanks! My well established 25' tree took considerable damage when we dipped into the high teens two winters ago, but it bounced back nicely. I've no doubt a young tree with a 2" trunk would have been killed.

One more little Jacaranda tidbit -- try to avoid pruning if at all possible. These trees will routinely produce copious numbers of unattractive vertical suckers in direct response to pruning.