watering advice needed for trees started from seed / tiny seedlings etc

Hi:
I have started several trees from seed, and have several other LITTLE seedlings I planted last Fall.......
But now I have no idea how much to water for their first year in the ground....
Germinated from seed....apple, pinyon pine, kei apple, carob, Jerusalem cherry, elm...
4inch seedlings...already beginning to grow.... variety of pines / cedars / spruce, service tree, yellowhorn, bay, manzanita, hazlnut, loquat, rugosa rose, olive, pomegranite...
Also I planted some "small trees" [11/2 ft]...Toyon, madrone
I have several trees / plants that are entering their 2nd year....I gave them a gallon of water / week once the land dried last year.........Do I just leave them "to it", or give a little drink every couple of weeks?
bald cypress, Arizona cypress, peach
deodar cedar, fig and elderberry had some / lots of "die back", but seem to be OK now.....
I also planted 2 cherries last year that failed at the graft...The root stock has sprouted and is doing great...Possibly plum??...... I figured I'd give them a couple of years or so to see if they would bear or not....Now I have all these growing I'm not sure what / attention they need.....
Thanks. Julie