Rocks don't promote drainage, voids do. A trench filled with bigger stones has bigger voids which means in can hold more water. The idea is to make a place that can take on hold water until the soil has enough time to absorb it.

Big voids can also be a negative because it is easier for other material besides water to infiltrate and fill the voids.

Um--so big chunks would be OK?

What "other" things would get into the voids? Anyhting I'd want to be sure to avoid?

So, I'm doing further reading on drains--and french drains. The recommendations I'm reading say the drain can be installed 10" to 2 feet deep. Another said 2 feet below the substrate. What's the substrate? Hardpan?

I thought I had to go below the frost depth, which is why I called the cemetary. I'd like to avoid digging 6' for obvous reasons--so what depth should it be?

Oh and Laag--I get it now. Roots and stuff. We don't want big gaps for them to come in and choke the system. But nothing lives six feet under--does it? (Don't answer that. Just help me figure out the depth thing.)
Thanks.

Here is a link that might be useful: Useful French drain article

OK, this issue is far more complicated than I'd realised. I just read some past threads and the article linked below. So, my question is: what do I need?

I want to plant things near my house (leavng 18" to 2' between the wall and the mature size of the plant.

I want to water these plants.

I don't want the water to enter my basement walls. We have not had any major problems. (A major downpour/hailstorm a few years ago did fill the basement with 2-3 feet of water which pulling the plug in the floor quickly drained. Two blocks over, folks had to completely rebuild their basements and the roof of a local mall collapsed.)

I have clay soil. To my eye, the land is flat.

I am not "allowed" to connect any system I install to the city's storm sewer sytem.

What do I need--if anything?

Here is a link that might be useful: Drains by the Paving expert

Lolly: as the purpose of the the drainage around your house is to remove any build up of water along basement walls the depth should be governed by the depth of the basement floor. The depth of the floor should be at least to the frost level which is 4 1/2 feet here in Quebec. The typical scenario around here is to have the water that drains around the foundations directed to a pit inside and a sump pump to pump it out and away. I suggest you have this done professionally as I don't consider it a DIY project with the best will in the world.

Burying corpses and correcting drainage problems have little in common. If you have serious drainage problems with your foundation, it is not a DIY or forum project, you should call in a pro and have it assessed and corrected. Installing a 2 foot deep gravel filled trench near your foundation on flat ground when you have no idea what you are doing can actually collect and direct water TO your foundation, creating a problem that you didn't have before.

Otherwise, the grade should slope slightly away from the house so that surface water will run off away from the foundation. I have seen recommendations for 1 inch of drop per foot for the first 6 feet, and 6 inches of drop for the first 10 feet, of soil around a foundation. I have seen some that call for less, so maybe someone else can advise you on the correct slope. Different areas seem to have different recommendations.

Shrubs properly planted in conditions that suit their needs should not need such extreme watering that you will create leaks in the foundation.

Clay soil naturally retains moisture longer than sandy or loamy soil. Chances are that once your shrubs are established, they won't need any supplemental watering at all (if they are chosen well). Do not amend the soil before planting, but rather choose plants that will tolerate the conditions that exist, and let them adapt to the native soil.

Saypoint and Ink--you are lifesavers.

We currently have no seepage problems. None. No water collects anywhere, not even in the big standing hole I currently still have at the front of the house.

This is another case where reading gets me into trouble! All the books push "drainage, drainage, drainage" and reading plx's posts are somewhat alarming! So I started thinking about it....

I'm purposely choosing shrubs which should be compatible with everything soil and water-wise as I'm a fairly low-maintenance kind of gal (and we are charged for our water usage, here.)--though I will, of course, water until things are established and I'll ask how long that needs to be when I buy my shrubs from the nursery.

Whew. So, I'll just go ahead and plant the couple of dogwoods I have definitively decided upon then. Maybe this weekend, woohoo! We're only six weeks away now from our first (mean) average frost date.

I was thinking what Saypoint was. If you DON'T have a drainage problem, then burying rocks or gravel against your house could simply collect water there for seepage into the basement. If it ain't broke, don't fix it. Drainage problems are pretty hard to fix DIY and usually involve serious grading and sump pumps like Ink said. Grading appears to be a difficult skill to master, from what I've seen even of professional jobs!

You will do yourself the most favor if you plant your stuff well away from the house--3 feet or so. It will grow up and fill in the space with foliage. Also, when you prepare your beds, mix some peat and sand into the soil, it will help it hold water better. Then the roots of your plants will take up the water, it won't leak into the basement. I had clay soil and I worked sand into all my beds before I planted them--best thing I ever did.

Thanks for the advice lpink. I had planned on placing things at least 2' from the house (taking mature size into consideration) just so we have access to it for washing windows and so on...but I had thought to shovel on some of the smaller concrete rubble we've got--just as a surface for walking, just so one isn't on mud when it's wet.

If I'm going to create a problem, I do hope someone will let me know! This is not a mistake I need to make.

The previous owner of my house (who is a civil engineer) had a few inches of stone next to the house on the side that doesn't have a downspout, and I see that in a heavy storm rainwater falls off the gutter in that location. I always thought it had something to do with drainage. As soon as I get home, I'm going to check and see if the stones are larger than the crushed bluestone that was in the adjacent driveway. Since the driveway is being shifted a few feet away from the house, I am in the process of planting grass where some of the bluestone used to be. Assuming that the previous owner knew what he was doing, I think I will leave that area alone so as not to mess with any role it may have in drainage. I have not had water in the basement even in severe storms. The lot does slope away from the house toward the road about 25 ft away, maybe a foot or two.

Re: stones next to foundation - it may be a drainage issue but it also may be so keep moisture away from the foundation (rocks dry out faster than soil and bark mulch). You don't want bark mulch up against a wood house anyway. Also, rocks keep splashing water from creating muddy spatters all over the foundation. Rocks won't harbor wood-infesting bugs.

I have gravel under gutters/near house simply to prevent splashing of dirt on the house. The rocks stay pretty clean, so little dirt gets on the house.

If you have any water issues, what you want to do is get the water away from the house. In many cases simply grading the dirt in a slope away from the house is sufficient. If it is not, then you will want to install underground drain pipes to help take water away. Connect those to any downspouts/gutters you have and slope them at least 1/4" per foot away from the house. depth of burial is really unimportant, just be sure it's enough so grass can grow over them (so say 6-8" deep). In the winter water will freeze not soak, and will slowly melt into the ground. If you have real water problems against the foundation, you could run some sort of surface channel into those pipes as well.