What you can do is run a soaker hose (a rubber hose that "sweats" water) around the shade garden, either on top or burried under a few inches of soil. Leading up to the soaker hose you can bury a "leader" (I don't remeber the right word, but it is a simple plastic hose) under soil and/or mulch, and then attach it to the soaker hose. You can get soaker and leader hoses and everything you need to attach the two & set up your system just about anywhere that sells garden supplies.

Then, when you're ready to water, you can just turn the hose on and leave it on for an hour or so, you don't even have to stand there with the hose in your hand. Even easier, you can get a timer (they are not expensive) and set it to water as often and for as much duration as you choose.

do you yank those out in the fall? if you leave them, i suppose they'll freeze. i'm going to try this this year and see what happens. probably the tree (which is huge and really doens't need any extra pampering) will benefit the most. :)

thanks!

Don't pull the hose in the fall. I ran a hose along with burried electric line to my greenhouses. Every fall I just blow mostly all of the water from the hose with my air compressor. Then cap the ends and I just hooked everything up again this past week. A frost won't bother the underground line (3-4") but winter freezing will damage if water lays in the line. I've had an old hose feeding our first GH without replacing yet(11 years). If you go under your driveway or traffic areas run the hose thru pipe or conduit for that section.

For your shade garden you might consider a soaker hose or install emitters to water specific areas. I won't tell you what to do there. Some people can get away burying lines and reusing them. For others, rodents and the kids games shorten the lifespan of the materials. But you are usually replacing a few dollars worth of materials.

I use soaker hose in my garden.
Now I am redoing my grass as I killed it (long story, do not ask)
I look at irrigation systems and that's just seems like a lot of hassle ... but here is what I though ... could I burry soaker hose in lines under the grass?
Any thoughts?
I know if the water does not stay in the soaker hose, it will survive winter ... my did already 5 or so. My thought is then, it should also work to water the grass ... right? Rather than putting pipes, heads, and whatever else there ... why not just put soaker hose?
Any advice?
Or should I simply forget about this and use portable sprinkler for my grass from time to time as required by the weather?

Could you add water-absorbing granules to the soil under that tree, the kind made for flower pots? They absorb lots of water, then slow-release it.

Or is that ecologically unsound?

Instead of hose you might think of well pipe and make connections at both ends it will never rot and as long as gravity is in your favor never freeze.

I put soaker hose in raised beds, with "leader" hose segments underground beneath the beds, twenty years ago. I have never had a problem, except when I put a fork through the hose! I suppose you could run "leader" (non-porous)hose underground from the soaker hose in the shade garden to a point close to your water source and leave it buried all winter if you could be sure it would drain. If one end was even slightly lower than the other end, that should do it. If the water drained to the soaker hose, it would "soak" through and not be a problem. You could try blowing air though the hose to clear any standing water, or you could stop watering a few weeks before the first frost and hope that any remaining water would evaporate.