It was suggested to you: "compost mixed in with the native soil is best "

Yes!

Seems to make sense: A clayey soil like we have here would require a great deal of mixing.

Have heard just mixing in large amounts of cattle manure works well - probably less costly as well, though I've yet to try it.

There isn't really a "best" amendment - depends on your specific conditions and what you are trying to grow. Not much wrong with planting mixes (stay with a 3-way, 5's are more expensive with little additional benefits) - they are typically a finely mixed combo of loam, compost and some sort of aerating material and IMO, are well-suited for preparing a lawn base. There is no need to and I would avoid tilling unless you are not able to bring in sufficient quantities. Lawns will perform best in a deep, loose, well-draining soil with a nearly neutral pH, so if you can manage, 6" in this area will work great without tilling.

If you can't manage that quantity, you will need to till to loosen up the underlying clay. I'd till first without amendment and again after adding whatever. Bailey's is darn hard to beat and I am seriously considering driving all the way out to Snohomish to bring back enough of their compost for this season's mulching.

Whenever possible, I'd recommend layering the new soil over the top of existing, poorer soil. You are far less likely to create any additional drainage issues this way and in time, plant roots, irrigation and the activity of the soil organisms will pull the better soil down and assist it in breaking up the heavier soils.

See the thread "Drainage amendments--PDX?" on March 24.

We roto-tilled our clay soil twice last fall and then brought in 30 yards of Pacific Topsoil 3-way mix and dumped it right on top (and mounded up some areas for interest). When I dig planting holes I mix the new soil into the clay soil. I've been really happy with the new growth on my plants but have had a lot of weeds germinate. Pacific Topsoil was awesome for us because we had the soil blown in with their truck. 30 yards would have taken us days to cart around to the back. I know a guy who has a beautiful half acre garden and he uses Bailey's to build new beds. He just piles it about a foot deep on top of his existing soil and plants right in the new compost.

Very interesting - I had the idea that whatever we did we want to mix it with the native soil, but you all have given me an idea. As part of our project we have put in a french drain line. Since I have had the opportunity to watch it rain like heck after putting in the drainline(waiting for the concrete pour for the concrete) I have can really visualize how clay soil can be used in our favor. Alternatively, how french drains are not very effective if you have low spots outside of the drain line. Our project is currently in progress... so the sod is stripped and I can observe the clay very easily. The soil is not yet contoured for planting as the drains just went in, the pipes for the irrigation were laid and covered and we are waiting for the concrete pour and deck build. (The downhill neighbor has been kept in the loop on the project because we didn't want to flood him or anything and he has been so grateful because he has already seen an improvement.)

How does this sound... once the hardscapes are in, use the loose clay that I have from the excavations to create very slight contours into the french drains. That will serve as our base, not packed, but being clay the water tends to run over the top of it. The main goal is to ensure that there are no low spots isolated from the drain line. On top of that, put a 3-way or compost with some soil too. That layer will be leveled. The idea being that the water should permeate the top part reasonably well, but when it hits the clay it will be directed toward the drain lines and not pool up.

I am not constrained by budget as far as bringing in compost or topsoil since the area isn't huge, but I am concerned about building up the height too much... 6 inches is going to put the lawn above my patio. It is so much work to haul out dirt that I am not going that route... so I may need to settle on 3-4".

My biggest concern about 3-way mixes is that I just don't know how clean that is. I don't want anything toxic or a bunch of weedseeds. That is cool that they can blow it in. I should do a price check compared to teen age boys and a wheelbarrel, cuz I ain't carting all that dirt around back!

After talking to Bailey's I feel more comfortable with their product, but they don't offer anything besides straight compost or mixed with some sand. Sand seems very controversial.

Anyway, let me know if you see any fatal flaws with my plan.

Sand is not controversial in professional horticulture and agriculture, or in soil science textbooks. The best all-around soil is a loam or sandy loam. There are some things that will grow better in clay, but nearly everything will grow well in sandy loam. If you have clay soil, there is only one way to get sandy loam: add sand, a LOT of sand. If you don't believe me, buy a bag of sand at Home Depot for $3 and mix it with an equal volume of your clay soil, and see what you get. Sandy loam soil dries out earlier in Spring, becomes tillable earlier, warms up earlier, resists compaction, and has better aeration which promotes better root growth. I have been amending heavy soils with sand for 40 years. I have never seen soil turn to concrete because of adding sand. I also add an inch or two of organic matter when I do a soil improvement project, because it improves soil structure. But the sand is most important, and is permanent. However, I would not attempt to amend subsoil clay. I would put a soil mix on top of it.

Get a textbook on soil science, or Google it, or try it on a small test plot. There is nothing controversial about sand. Sand makes up one third of a loam soil BY DEFINITION.

Google "soil triangle" and all will become clear. Note that organic matter does not appear on the soil triangle. You can make any kind of soil type with sand, silt and clay. Once again, organic matter does improve soil structure, but its effect is temporary. Sand has a permanent effect. I added sand to my heavy clay loam soil in 1988, and turned it into sandy loam. I still have sandy loam soil today. As I have said, and as the WSU link says, it takes a lot of sand. However, it does not take 50%. 50% gives you a sandy loam soil (see the soil triangle). 33% gives you a loam soil, which is a very good soil. This assumes you are starting out with a decent clay soil, not some gray, stinky subsoil clay. A decent clay soil has some silt and a little sand in it (see the soil triangle), can be dug with hand tools, and supports healthy plant growth. You can turn this soil into a loam by adding sand. If you have pure clay, you can't turn it into loam unless you add a huge percentage of sand, like 90%(see the soil triangle). I once bought a house in New Jersey where the developer had removed nearly all of the native sandy loam topsoil. What I had left was gray clay that stunk of methane. I could not penetrate it with a shovel, a pick, or a tiller. The only thing that would cut it (very slowly) was a tractor-mounted Ditch Witch. Oxygen could not penetrate this clay. When organic matter decomposes in an anaerobic environment (no oxygen), it releases methane. The only thing to do with this stuff was to pile good topsoil on top of it, and put in a drainage system to carry away the surface water that was trapped above the clay. I put a foot of sandy loam on top, and everything grew fine in it.

If you don't know what to do, have your soil tested for texture. They will tell you what you've got. Then look at the soil triangle and figure out what you need to add. Or, try the experiment that I suggested. Buy some sand and till it into a small area of your yard. Try to get 50% sand by volume in the finished product. Obviously, you shouldn't till gooey-wet clay. Wait until it's reasonably dry to do this. See if you like the result. It usually works great. If you then add organic matter or an organic mulch, it gets even better.

As I pointed out in the 3/26 thread, if you are going to amend your soil to great depth or amend a large area, you should consider renting a tractor with a bucket and tiller. Or hire someone. It will all be done in a day and you can rake it out and start planting.

I do not have the gray clay - I have seen that before when my parents had a well dog for livestock water many years ago. The gray clay was really like modeling clay - this is not anything a child would recognize as clay - it is very heavy soil. This stuff is a clay mixed with silt (well some sort of grittier texture). You can work it with hand tools and till it with a little mantis tiller, with effort. It grows plants, I have grown hardy fuscias, calla lilies, day lilies, a redtwig dogwood, ferns and a host of weeds that like moist soil. I even had a little salad garden going at one time - lettuce, various greens,radishes etc. As I mentioned in my first post, it doesn't grow grass that well and the old lawn became very weedy and mossy. I have added drainage and am just looking for input on how to improve the soil for bringing in sod.

Thanks for all your input and I will take a look at the soil triangle. It made sense, but I haven't actually done the tests it recommends.
Sheryl

1. Buy topsoil

2. Dump on top, shovel and rake out

3. Plant, mulch, water

4. Done

To throw a little alternative stuff into the mix, the soil here grows grass fantastically. Most of my weed problems are grasses. Grass here will "brown out" if not watered in the summer, then greens up in the fall when the rain starts (summers are dry for 2-3 months straight). I personally if getting a shot at a city lot to landscape would be grass-free. The yards I like best have heavily mulched paths between heavily mulched beds with soaker hoses underneath. A scattering of neat small trees like Japanese maples, figs, apples, pears, evergreens, give height interest and shade, clematis are grown on trellises or posts, and a wide selection of perennials give a succession of bloom during the growing season and interest in the winter. My favorite succession would be to start out the year with Helleborus orientalis, daffodils, tulips, and Pulmonaria, then move on to roses, peonies and daylilies, then finish out with dahlias and fuchsias. There are interesting evergreen and deciduous shrubs with fragrant flowers, etc. Mulches are the way to slowly amend the soil nature's way, from the top and slowly. It preserves the natural ecology of the soil layers, earthworm burrows, etc. Check out the Soil, Compost & Mulch forum.

>Mulches are the way to slowly amend the soil nature's way, from the top and slowly. It preserves the natural ecology of the soil layers, earthworm burrows, etc.Absolutely.