Hey Mopower,

There is no one-size-fits-all amount of water for your trees. Same goes for timing. All kinds of variables determine how much and when you should water. You may need to water half or twice as much as the guy down the street with a little different soil profile.

You can make the determination yourself, however, for your specific situation. You need to find out how soil moisture works in YOUR yard. Read the article, linked below, and pay particular attention to section 12 (it addresses your question).

Planting a Tree or Shrub

I understand that, but heres the deal..My hose wont reach where the trees are, so i want to take buckets and drill a small hole in the bottom of them and put water in them and set them beside the tree so it will slowly water the trees when they need it, BUT, im not sure how much water to put in each bucket per watering for trees this small? They were bare root plantings about a foot tall..
Just pouring water around the tree, it seems it only needs about a quart to really moisten the soil 3 inches down...

Unless your soil is really, really, really slow draining (in which case, growing most trees there may be a problem anyway), I'd just go ahead and fill the whole bucket up. When I water small trees on my farm, I always use at least four or five gallons of water. Longer (deeper), less frequent watering is much better than shorter (quick), frequent watering.....and I really doubt that 5 gallons of water (trickling out slowly) will be too much water.