A) It takes 2-3 years after planting for a tree/shrub to be considered "established", so you will HAVE to water this year, not so assiduously next year, and in long, dry spells the third year. You need to water more frequently in the first few weeks after planting as the roots are still recovering from their planting.

B) You need to water for the equivalent of an inch of rain per week, applied in a slow watering, so the water gets to the bottom of the root ball. This can be done by: setting a hose to a slow trickle and leaving it there for long enough (which depends on your soil - sandy needs more, clay needs less but slower)); getting a "tree-watering" soaker hose section to connect to a hose and leaving it for an hour or more; or by drilling small holes in the bottom of a 5-gallon bucket (or 2 buckets), filling them and leaving them at the up-hill side of the tree to empty themselves. I am assuming that you left a "lip/moat" on the downhill side to catch water and direct it to the roots?

C) You can only tell how much water is enough by checking the soil - check the root ball for the first few weeks, and then the soil next to the root ball. The weather, the soil you have, all these things affect how long the soil will stay moist. Check by sticking your finger into the soil up to the second knuckle - if the soil is moist at that level, check again the next day. If it is dry, water. A pointed length of dowel will also serve - you just need to check down about 2 inches.

D) If you haven't, mulch. Use any good mulch - since it is on a slope, avoid pine bark as it will wash away in heavy rain - it floats. Spread it as widely as you can, at least 3', no deeper than 4", and put no mulch in the inch or so next to the trunk. Do not put any plastic or landscape cloth under the mulch - it inevitably comes to the surface, roots grow into the cloth, and it doesn't deter weeds very well. And check UNDER the mulch when checking for watering needs.

Thank you very much for the detailed response. I put a soaker hose around the plants, about 2-3" around the trunk. I also added a light layer of leaf mulch around each. I plan on adding some bark mulch on top of that in the next week.

I tried the soaker hose, but since these shrubs are on an awkward slope, some bushes got more water than others. Plus, there was ALOT of runoff in areas between the bushes where there is no lip to hold in the water. I was thinking of using a hose with a small hole right at the trunk of each bush. Low water pressure. Do I need to tie some fabric over the hole to disperse the stream? Does this sound like it would work?

Thanks again
Shelli

Shelli, that sound like it would work. Just check to see that all the trees in the line get enough water - it may be that the ones at the end will need larger or smaller (more or fewer) holes than the ones at the beginning of the line, to be sure all of them get enough. I don't know what the needed pressure would be to get to the end of the line - it MAY be that the beginning will need something to disperse the force of the flow, and maybe not. I would have the hole be as far up the hill as possible, since you want to water the entire root ball, and not just the down-hill half. You can get hose for "spot-watering" set-ups - there is a name, but it presently escapes me - that uses light-weight black plastic hose, comes with a punch and emitters, and plugs for wrongly-punched holes. It's easy to set up - can be ordered (Peaceful Valley, Gardener's Supply, FarmTek, etc.) or bought from a good garden/nursery supply place - the big-box stores might have it as well, as a kit.

If you aren't using municipal water, or aren't on water restrictions, and if the water isn't doing any harm, you could just let it go. If any of that list apply, then you should deal with it somehow.