I have read that I can perhaps mix sand at this time to help with drainage. Any opinions on that?

Rather you telling the contractor what to do, why not hire a contractor who tells you what needs to be done.

Hire a certified nurseryman or certified landscaper.

They will have local experience and may perform tests.

Jim Mat(9) Sure, but I would like to do as much of it myself as possible as a learning experience. I'm trying to figure out what the steps are, and I have found that people here are also knowledgable. I'm curious to see what methods others have used and if they have worked. I have a neighbor who hired a certified landscaper who amended his clay yard with small gravel for better drainage and it is a pain in the neck to dig into it now.

If you want to add sand, you will have to add a very large quantity or risk turning your soil into something like cement. Soil tilth is dependent on the quantity of organic material in the soil and the size of the soil particles. Sand particles are larger and clay particles are smaller. There is no way to make the clay particles bigger than they are. Adding organic material will help with drainage, but they will break down with time, so it will be an ongoing process, not one and done. Here's a good article to read: Imrpoving clay soil

Beth Chatto's garden is in England and gets rainfall every month, not like California, so you might need supplemental water. Even native plants will need to be watered the first year you plant them. They are not instantly drought tolerant.

After you excavate the existing soil replace with good topsoil and then you are ready to plant (do not do any mixing of the two soils together, as you will then be introducing a component of the too heavy soil already there into the lighter textured soil you have just paid to have placed on the site).

lgteacher That was a great article. So they layered 8-10" of mulch on top of clay soil and ended up with loamy soil in 1 month? Was this because the mulch created an ecosystem that allowed critters to come in and naturally turn over the soil or for other reasons?

If I were to excavate about 10" down, fill in 4-5" top soil, then a layer of cardboard and kraft paper for weed prevention, and then 5-6" of tree chips/mulch, would I similarly create such an ecosystem? Or would the mulch have to be touching the clay soil directly.

Embothrium Is there a recommendation for how many inches of top soil I should have? If I were to excavate 10" down, fill in 4-5" top soil, then a layer of cardboard and kraft paper for weed prevention, and then 5-6" of tree chips/mulch, would that be enough top soil? Could I do less?

JXBrown I have not tested it yet but I plan to immediately. I was just googling soil testing online. I believe it is really clay. It does not drain well at all (which kills my citrus in the winter), and then when it does in the summer dry weather, it develops great big fissures.

Which "Bay Area" are you located?

I am in Silicon Valley CA, my soil was amended with sandy loam, mushroom compost, redwood compost, and peat.

I did not remove existing soil. Previously, my area was a walnut orchard. I am in a flood area. I read an article at the library, my area was a wheat farm in the 1800's, dry farmed.

If you remove soil, will that affect area drainage.

Jim Mat I am in Berkeley, CA up in the Tilden Park hills. "Silicon Valley" is a very large area with lots of microclimates. San Jose?

That sounds like a very nice mix. I learned from a neighbor that the land my home is on used to be a pig farm :)

How did you amend your soil without removing soil? I think I would need to remove some dirt first, as otherwise the mulch topping would be several inches higher than driveway/walkway/sidewalk and blow all over the place.

I tilled the amendments into the existing soil. The surface was ~1-2" higher than existing walkways.

I may have used 3-4" of: peat and compost, and 2-3" of sandy loam. After ~35 years, the prepared areas are ~1-2" lower than existing walkways. The surface of the lawn now resembles clay: cracked. There is no compost or peat in a shovel ful after ~35 years.

Location is: South San Jose

You want to change you growing environment, why? What are your objectives? I wanted to grow a front lawn.

Before you go to the tremendous expense of having soil removed, hauled away and replaced with who knows what they're selling, just add compost. You can even spread freshly chipped wood (it's free!) over the area. It will break down pretty quickly and the soil level will sink. Clay is very good at holding nutrients and water in the soil. You really just need to add organic matter. The level will take care of itself. You can much more easily amend your native soil than dig it out and replace it.

If you create an interface between soil of one texture and soil of a different texture as Embothrium suggests, you'll create a drainage mess.

Did you add amendments to the soil that you backfilled around your citrus? If so, that would explain your drainage issue. Planting them too low could also have caused your problem.

JXBrown No amendments and we planted on mounds. They didn't last our mild but rainy winter. And we think it is because of the drainage. There are old established citrus in the area that fruit beautifully, but other neighbors will young trees like we planted also ended up with failing trees.

I did plant a neem tree with half compost and half sand and that is thriving. Normally those trees would die in the lack of drainage we have.

I never fill a planting hole with anything but native soil. If you truly have clay,

plant things that grow in clay.

Tilling the soil will bring up weed seeds.

I attended a wedding at Tilden. I'm fairly sure many things can grow easily in the area.

Jim Mat I want to grow fruit trees and perennials. As many others have mentioned, I should be okay if I plant native perrenials since they will take the soil. The fruit trees seem to need better drainage for winter rain to succeed. I do believe our clay soil is high in good plant nutrition because I tilled our large backyard a year ago and planted rows and rows of vegetables farm style. I amended and mixed soil in the holes for each tomato/pepper/eggplant/beans/etc and I had some of the biggest healthiest vegetables Ive seen outside of my native India. I guess it is just hard to access with its large particles and tendency to clump in the wet winter and develop 3"+ wide cracks in the summer

Have you calculated the amount and weight of the soil you are planning to remove? Figure 1.5 tons per cubic-yard.

You will need additional fill by volume because the new soil will settle and the organic material will break down. Eventually, unless you continue to add organic material to your "new" soil, you'll be right back at square one, with added drainage and soil level issues.

A soil test and a drainage test will help you determine if you actually have a drainage problem. Cracking is common in summer dry climates and not really a sign of a problem.

Soil cracking from drying is an indicator of clay.

JXBrown You're right. Quite a bit. I checked out Roy Diblick and Piet Oudolf's books from the library this morning. I'm going to plant a meadow style of perennials of plants that work with my clay soil, and try to help with drainage for my trees via yearly toppings of compost/horse manure and several inches of mulch. Let's hope this succeeds.

I'm pleased to hear it. If you have not started composting you should start.

Clay soil is amended with compost and aged manure dug in about a foot. Gypsum is also added to make clay drain better. Never add sand to clay.

You will be much more satisfied with that path. Also, your spouse will appreciate the money savings.

"Arborist" wood chips which are free waste material, will give you gorgeous, grow-anything-soil, although they may make some of our picky, poor soil loving natives unhappy. My mom used to "spread" arborist wood chips (hint: she had two "perfectly healthy children" to "do it because I said so") and the results in a season or two were amazing. Also, unlike soil, they can be shoveled and moved by scrawny girl children.

The path is beautiful, JXBrown!

Also, google "Miguel Urquijo". He's a Spanish designer who was featured in Fine Gardening this month. Stunning meadow-y gardens with Mediterraneans.

Gypsum is beneficial if you have sodic soil. Does a white crust from on top of the soil after it rains? If not, you don't need gypsum.

emmarene lgteacher JXBrown Is there preferred weed barrier?

Im going cut out my grass with a sod cutter and then till the soil below a bit so that I can do some necessary leveling/grading. Then I was thinking of using cardboard and kraft paper and then a few inches of mulch or arbor chips.

Before you remove sod, check to see if it's &@*%# Bermuda grass. If it is, you may want to consider a couple of applications of Roundup. If it isn't Bermuda, keep the sod. One of the best vegetable gardens I ever started was on a pile of upside down sod that I had removed from the front yard. I let it sit over the winter and it appeared to have broken down very little when I planted, but the vegetable yield was phenomenal.

If you don't need to grade, you can also just lay the cardboard and mulch directly over non-Bermuda grass. A six inch layer of mulch will eventually be a zero inch layer of organic material blended into the soil. A six inch layer will also settle and shrink in height noticeably in a few weeks. The chips will be pretty easy to disturb at first, but then they kind of mat together and stay in place better.

I always used to use a thick layer of newspaper under the chips. Hah! That's how old I am! Now I use cardboard -- mostly from Amazon, it seems.

i grew up in Maryland and Linda Chalker-Scott, whose article I referred you to, works in Puyallup, WA. Both of those places have more than 40in/100cm of rain per year. The extra moisture helps to break the chips down very rapidly and gets the organic material into the soil quickly. Even in NorCal, it will be slower for you, however, it will help conserve what soil moisture you do have and you'll be replenishing the mulch much less frequently than in the rainy climates. Especially if you are spreading it this summer, you'll want to make sure to have some moisture in the soil first. The fungus, bacteria, insect life, and worms in your soil will be "tilling in" the organic material for you eventually and they like a little moisture. Until the cardboard gets saturated and begins to break down -- a pretty quick process since it's made from wood pulp -- water applied overhead may tend to run off.

Wood and paper made from wood are full of lignins. The end product of lignin decomposition is humic acid and humic acid does magical things to soil. You'll be cursing the pile of wood chips as you trudge back and forth with your wheelbarrow, but you'll love the ultimate result.

Clay soil retains moisture and is loaded with nutrients. It's not bad.

It is heavy and is not good for plants that want a high amount of oxygen for their roots, such as Proteas. It is hard to dig in.

Every type of soil has advantages and disadvantages. Even loam has disadvantages--moles love it, so do weeds.

You learn to garden with what you have.

I don't use weed barrier, I hoe weeds. I also use pre emergent weed preventer sometimes and weed killers in areas I deem it safe enough. When I used gypsum it was because of the salt in my soil. It is specific to my area and may not apply to you.

JXBrown Thank you for all that info. Ive started removing lawn and we do have bermuda grass (the last owners were v green lawn happy). I wonder if I should apply glyphosate now and leave the dirt open for some days to kill weed/grass seeds? Then I can cover with cardboard, heavily wet, and then cover with thick layer of mulch at the end of this month until September. Perhaps the mulch will break down a little by then. In September, I will put in landscape plugs and my fig trees (does glyphosate affect fig trees?)

Thank you emmarene, hoovb zone 9 sunset 23 ... I don't think gypsum will do much for us. There is a lot of natural pine needles mulch here and I don't think we need more calcium. Hopefully yearly topping applications of mulch and compost will break down my clay soil and make that great nutrition more accessible.

Glyphosate breaks down very quickly and your figs will be fine. You don't need it for most types of grass, but Bermuda is tough to kill and won't die off even if you bury it.

Bermuda is tough to kill because the roots can go down 3 feet, and the plant can come back from those very deep roots. The usual advice is water deeply, get the Bermuda growing vigorously, apply plant killer. Repeat several times over the course of a year, until the Bermuda stops coming back. Wait through a rainy winter to see if the Bermuda starts coming back in late spring, if you really want to be rid of it. Even after all that, you have to be vigilant. I had some bits that came back for ten years because the roots went so deep. Pull out the stuff as soon as you see it to weaken the root system to the point where it doesn't come back.

Re cardboard--this is a technique that works well in most areas of the country, not so much in California. Here where we have a long dry season, cardboard doesn't break down the way it does in areas with summer rain and a long period of heat coupled with high humidity. Breaks down fast in those conditions! Here it tends to dry out and remain.

When you say plant plugs, what plugs do you mean?

I've used cardboard in SoCal. It breaks down reasonably well, if not perfectly, as long as it's laid over moist soil and covered with a good layer of mulch. It doesn't break down if it's laid over dry soil in the summer. I have Netafim drip lines which may help with the break down. Cardboard and chips sure make lovely soil, but a thick layer of chips without cardboard as long as there is no really obnoxious weed should work well too.

emmarene I mean landscape plugs, like the small plants you can buy in the fall for $0.50-2.50 instead of paying $25-50 for a slightly bigger plant in a big pot.

Is there a recommended type of wood that I should request when I call my local arborists for arbor chips? I like the smell of pine but are certain woods a better choice?

emmarene, JXBrown, hoovb,

I doubt if they segregate their wood chips.

I had called the arborist we used to remove our trees and they asked me what kind of wood I'd take. emmarene

I was told I should refuse black walnut.

Linda Chalker-Scott says that it doesn't matter. I don't think you'll get black walnut around here, but eucalyptus has a similar effect on plants growing under the living tree. However, according to LC-S, there is no problem from chipped wood. I used to make compost from fallen euc leaves all the time and it worked fine despite having the characteristic odor. Termites are also not a problem.

JXBrown "characteristic odor" Did it smell like eucalyptus? I very much enjoy the smell of eucalyptus but once I learned that they have a lot of oil in them and are more flammable. Could that be true? I imagine any kind of dry chips or mulch is flammable.

They say that chips aren't flammable, especially in contact with the soil. The idea is for them to get wet and rot!

Yes, eucalyptus leaf compost smells strongly of eucalyptus. Everything else pretty much just smells like generic compost, but the eucalyptus odor hangs around for a long time. Since most of my life has been spent in San Diego, it smells like home on a rainy day.

I was considering taking out my Zoysia grass lawn and read up on differing methods to get rid of it. The most promising called for smothering it with cardboard and then adding 6-8" of compost. You'll have to water it, but in a few months it turns the sod into something you can almost dig into with your hands it is so soft and friable. This is partly the magic of soil organisms.

Bermuda grass calls for special measures. Namely an initial application of Roundup followed by several cycles of watering and killing any sprouts. You really do NOT want Bermuda grass contaminating your new planting,

echolane We're in process of getting rid of bermuda. We're on spray+water 2 of Roundup and will be doing the 3rd next month. Hopefully that will do it.

I was going to use the sheet garden style of getting rid of grass, but unfortunately we have grading issues that we need to fix. So we have to be dig out the dead grass and fix the grading issues by taking out some dirt. But I definitely will be using that method for the backyard.

For the front, after we dig out the grass and re grading, I was planning on laying down some brown kraft paper and then covering it with arborist chips. I have crabgrass and I wanted to apply preemergent for it. Will it get through the paper and chips? Or should I apply before I put down paper and chips?

JXBrown If we dig out the grass, should I lay down a layer of kraft paper before throwing arborist chips on top for weed control? Or will it not do much and arborist chips are enough?

The only reason that I use a thick layer of newspaper or cardboard is because that's how my mom did it. I don't think the kraft paper will help because it will break down too fast. Just spread the chips and stay on top of the weeding.