The blue gray clay is tough to work with, but it can be done. This clay has a complete lack of oxygen, and very few plants will do well in this soil. Raised beds of good topsoil is the quickest way to deal with it. To make the existing soil garden worthy will take several years of tilling in vegetative matter. Hauling the clay away is really not an option. Al

Lots of mulch and time will help that soil too. Be careful about creating bathtub conditions by digging down into the clay and filling it with a well draining soil. That will kill plants too.

Many plants will do fine once they get established. The problem is discovering which plants! Rudbeckias don't do well in my yard at all, and I have great soil, so perhaps it's the plant. The Breath of Heaven may bloom this coming spring. It only blooms once a year, but the bloom lasts quite a while.

I feel your pain.

Others which look ok but are not blooming ( Breath of Heaven)

Spring bloomer only.

Easy way to loosen you soil is to mulch with a good quality compost. When the mulch gets thin, mulch again. Repeat and repeat and repeat and repeat. Earthworms will pull the mulch down into the soil and convert it into nutrients plants can utilize. The worm action will also incorporate more oxygen into the soil. In about five years you will have the best soil in the neighborhood. Yes, it takes time, but good things come to those who wait, and throwing some compost down is a lot easier than digging in stuff. The best gardens are years if not decades in the making.

Ah thanks for all the quick answers. You all make
me feel so hopeful.
Al , I may have mis-spoken . My clay is actually more on the brown side. Not sure why I said gray. Early morning mistake.
Hope to avoid "bathtub condition" . When I plant I add compost along with some of the clay bk into the hole. So as to create better drainage yet not loose the benefits of clay. My last yard had sandy rocky soil, which drained too fast. Sounds like I am on the right track. I will continue to add in the compost . Need to remove a substantial amount of clay to make room. But will be careful.and try to be patient. But no not 5 years! am tired of looking at bare earth. How I would love to see earthworms!!
Breath of Heaven: it did not bloom this past spring 2013.will hope for next year. I have two ,purchased them about a year ago. They have not bloomed yet.

This post was edited by annemarieo on Thu, Nov 7, 13 at 9:37

Brown is better, when it is clay. Your soil will improve every year as you work with it. While it may take five years to reach the 'best it can be' you will be able to garden all that time, you will not be looking at bare ground. Good luck with it, it is worth the effort. Al

I did remove about 3 inches clay in one bed (shoveled aside the top layer and took it from underneath).

Because when the soil is loosened it raises the level too high. Added 2 inches of organic matter (dry leaves, manure, nitrogen reinforced redwood sawdust, coffee grounds & vegetable scraps, etc.). Kept turning the soil every couple of weeks and in 3 months it was ready. Worth every backache! Did have a rainstorm during this process which helped.

I'm doing one now where a huge deep hole to find pipes threw the god-awful stuff on top. It's going to the trash bit by bit as I chip up chunks.

I can't do raised beds in bk yard. It is already surrounded by cement block beds about 3 ft high. I guess raised beds of sorts. I have removed some of the soil to the trash and added in compost.I can't just add compost and mulch to the top. It would fall over onto the cement patio below. I suppose I should attempt to post a pic. But not sure how. I have recently joined snapfish. I wonder if that would wk.
Gardengal, it is interesting what you say about not adding compost into individual planting holes. Which is exactly what I doing.I do backfill with some of the clay. Though I do dig a wide hole they are usually 2-3 X s deeper then the size of the plant.Here I thought I was helping improve drainage. This is why I love this gardenweb. One can learn so much!! I was worried the roots could not get through that heavy soil. So I add compost to loosen it up. I can
Not quite picture if planting high and mounding soil up would wk in my beds. But I will try. Ok time for sleep. Goodnight all

I successfully amended my clay soils at almost no cost. When I started, I would dig up solid chunks as big as my shovel. Three years later, the soil crumbles well although small chunks of clay remain -- but they're decreasing each year. My garden is very productive now, noticeably more so than the first troublesome year.

You simply need to add organic matter (e.g. compost), mix well, and break up chunks.

Do not add sand; you'd need to add a huge amount (e.g. 1/3 by volume) and it's not free. Adding a small bit of sand wouldn't help.

Compost is free if you have a tree. But again you need a lot, so maybe start by doing only the top 1/2', then going a bit deeper in successive years.

I use two composting bins, so I'm not emptying one with fresh kitchen waste. I save all the fall leaves and put them through a leaf mulcher, which cost $100. Mulched leaves don't take up much volume. Over the remainder of the year, mix the leaves with the kitchen waste in amounts to keep the compost moist but not too wet.

Besides leaves, wood shavings/sawdust work great but are optional. I cut a bit of firewood with a chainsaw and use that, but you may be able to find a free source on craigslist. I often see free mulch on craigslist (with free delivery even), but the wood chips can be a bit large for mixing into soil so I haven't tried that but maybe someone else can chime in if they have.

I break up chunks with a shovel but it's a bit of work. Leave the hardest chunks on the surface -- they dry out and crumble in a few months.

When you turn the soil, it'll be high at first and settle maybe 4" after several months. But you will have to remove some soil if it's level with the top of your concrete blocks already. Maybe you could use your extra soil to fill planters elsewhere?

Never never never dig the planting hole for perennials deeper than the root ball. What happens if you do is that the soil below the root ball is now fluffy and uncompacted. Over time it will naturally recompact. That will cause the plant to sink. Then the basal root flare is below grade and will eventualy get covered with soil. Then you either get crown rot or girdling roots that eventually kills the plant.

Try not to add compost to individual planting holes. Not only is it not recommended for non-clay soils, it is highly inclined to reduce drainage in a heavy clay soil regardless of how carefully you attempt it.

Another problem with digging organic material into clay is that as the organic material decomposes, it competes with plant roots for the oxygen in the soil. Plant roots need three things: water and nutrients are the two obvious things, but oxygen is also critical to root life. In nature, the organic material goes on top of the soil (think forest floor) and eventually leaches its way downward fully decomposed (and therefore not competing for oxygen) or is pulled downward by the bioherd or earthworms, also mostly decomposed through the digestive process.

Clay soil is good soil--it holds moisture well and has plenty of nutrients. Where it is not so good is in oxygen content. Earthworms are the great value here because their tiny tunnels as they go up and down from the surface downwards creates air pockets.

I have been gardening for years. But I am finding clay very different. You all have been so helpful. I am really glad I started this thread. I can't wait to put it all into action. Only shallow holes for now on and I will only add the compost to top layer right below and with the mulch ;or as the mulch. I have had a worm bin for years. Just a large Rubbermaid chest with holes drilled into sides. Had to buy compost recently though. Couldn't make enough.
I am still surprised about what is being said about not putting compost into planting holes. I have heard many times how gardeners do this. It makes sense not to I guess. But could all those gardeners be so wrong?

The problem with treating each planting hole separately from the native soil is you create layers of different soil composition. Roots do not readily cross these layers as they grow. For myself, If I do not want to amend the entire space, the minimum I will do is 16 square feet, or a 4x4 foot area, for a single plant. Al

Al , I guess one thing I am up against is my gardens are partially planted. I don't want to disturb plants as I amend soil. I will have to work around these plants as I plant the new ones. I know ideally one should amend the whole area before planting. I did this to this area to a degree. But the clay seems to eat up the compost and I feel I need to add more.

If you keep topdressing with compost, it will work its way in. Check out some of the work done by Dr. Chalker-Scott. She has done some restoration work on heavy clay soils with just a lot of mulch. Also, she bare-roots all her perennials to eliminate container medium/native soil interface problems. Her horticultural myths page is worth a read. warning they are all PDFs.

Here is a link that might be useful: WSU horticultural myths

Thanks for sharing nil13. Interesting what the it says about newspaper mulch. I used it I. My garden few months ago with wood chips to suppress weeds. Most especially burmuda grass. A lavender plant I had planted at the time died a while later. Wonder if it had anything to do with the newspaper?
Am in the process of extending my garden bed. It is invaded with and surrounded by burmuda. I have been reading about killing it with roundup+ layers of newspaper mulch compost. Now Imwonder?? Need to keep researching .

Place the plant in the hole so that 1/3 to 1/2 the root ball is above grade.

What about root balls with roots on top? Shouldn't those roots be covered on top with soil rather than mulch (especially if that mulch is bark)?

If you are fighting bermuda grass, the best way to get rid on it is with multiple grow/kill cycles with roundup. Bermuda grass laughs at sheet mulches. To be honest, dealing with bermuda grass is a long term endeavor.

Yes , I am discovering that first hand. Didn't buy Roundup yet. But treated x2 so far over last few days with a more another weed grass kill formula . Name escapes me but it is more green product. Not sure yet how well it is working. Will buy Roundup if I have to. Was difficult to come to that decision but my body can't fight those weeds anymore.
I read about folks who did what you say Nil and then covered the area with many layers of newspaper compost and mulch. This is what I have been considering. Though one thing Problem I have not solved yet : part of the garden is already has some plants in it. I will have to work around them.

Bermuda grass has bulbs attached to the roots, roundup kills the roots, but not the bulbs, which then send up new stems. That is why it is a multi year program. If your neighbor has it on his side it will come under the fence into your garden. Covering the soil will only delay its next appearance. Diligence in attacking it as it appears, and lots of patience will win the day. Al

Roundup is fairly innocuous to the environment if you restrain from spraying it out of the back of an airplane. It breaks down very quickly in an irrigated garden environment.