I can seriously commiserate with you on this one. The higher part of our land is also heavy hillside clay. As for what you propose, I have a hard time picturing what it is you intend to do. A hundred plastic pots on a hillside with no flat areas? How will they stay put? How will you water them? I don't know which part of California you are in, but vegetables are very thirsty under the best of conditions. It's possible that you will be watering every single day, maybe even twice a day if you have a hot climate. Do you have the time for that? And would watering mean dragging a hose up and down a hill covered with a hundred pots? That doesn't sound too easy or fun? You don't say if the hill is south or north facing. If the sun is on that hill all day long then the plant roots in those pots are going to be under a lot of heat stress. I have found that very cheap plastic pots tend to deteriorate much more quickly in the sun than more expensive pots. Some don't even last a year in the sun. And finally, if you cut out the bottoms of the pots you would have to dig each pot into the ground or else you are going to lose all the soil out of them every time you water. I think you may be setting yourself up for a lot of work and a lot of frustration.
What we do here with our hillsides is to terrace the land. (If you look for images of Banyalbufar in Google you will see what our terraced lands looks like) Would terracing be possible for you? Even on a small scale it can be very effective. On this island we build up our terraces with supporting rock walls but in the States you would probably use wood.
Google "build hillside terraces" for ideas. With terraces you will have flat areas where you can build up your soil, for example, with the lasagna method which is reasonable cheap to do.

Well I wouldn't recommend clay soil for containers but sometimes you just have to use what's available.

Al's container soil thread is excellent and should answer many questions about container soil mixes. It's located in this forum, called "Container Soils - Water Movement & Retention VI".

Good luck.

Dave

You can use the clay/compost in your container if you use the containers as raised beds rather than containers. Cut the bottoms off and for stability bury them a few inches. The critical part is that the soil in the container makes contact with the earth.

Alternately if you prefer to grow in the ground you can dig trenches perpendicular to the slope and fill those with water. This will hold the water until it can soak into the soil instead of it just running off. Plant a row next to the trench and the water will move into the root zone of those plants.

If I'm to get straight to the point, I'll say that I can't imagine any combination of clay, compost, manure, and sawdust working well enough to yield anything that would justify your efforts. Removing the bottom of the container or insuring there is a soil bridge between the container soil and native soil changes the physics of the container to the degree that your project would be fairly close to growing in the ground, but you still have the obstacles of water retention that will increase as soil collapses, N immobilization from the sawdust and perhaps compost (depending on how close to 'finished' it is), and other issues.

Al

I have a slope in the back of our yard, and I have clay.

Clay + anything = clay + anything. Years after you put it together, it will remain separate. Even if you take the time to crumble clay and mix it with compost, the two don't seem to make a soil. They are two things working separately - or not working at all.

In my slope for my roses, I cut way back into the slope. In doing that, I built up the front bank of where I was going to plant with the clay I dug up. It works almost as well as cement. I dug down more than a foot, and dug across probably 3 feet, and back into the slope about 2 feet. I made sure that the back was solid clay, and that the front was a ledge of clay even though it slopes down.

After all my digging, I filled the area with a mixture of store bought top soil and mushroom compost. I planted my roses, and watched them carefully the first year. Now they are all over 6 foot tall even though I cut them back yearly - in other words they are thriving.

I gave them a growing medium of soil that was a foot deep, 3 feet wide, and 2 feet back. Now the roots of the roses are holding the soil.

If you want to use your slope, just cut way back into the slope, and change the soil. There are many products you can use for support, but I don't think clay will mix with anything. I also think you run the risk of drowing your plants if you don't have good drainage.

You might even get a ledge and put pots on cement blocks, but in my opinion that ugly clay might as well be cement.

Sammy

Hi californian,
My experience on tropical clay slopes is not container gardening; but I will chime in, since initially notches out individual clay basins to contain plant in.
(If I am breaching forum etiquette, please pardon my mistake.)
The practice is similar to agro-forestry; ie: on a slope use a vegetative hedge, ammend uphill from the retainer plants & let the build up soil serve as a terrace.
Here is my tactic.
1) use a pick to notch out individual planting basins & remove the clay, which then use for exterior contouring
2) in each basin put best available growing substrate according to what intend to grow & whether planting from seed or transplanting seedling
3) integrate your choice of watering design elements (I use perforated, vertically buried pvc pipe above/flanking each notch to pour fertigation into)
4) down hill from each notch I plant a rooted Vetiver grass to stabilize against run off erosion, maintain soil moisture, repeatedly cut it's leaves for mulching the growing crop & self-propagate it's shoots used to expand the hedge terrace (agro-forestry done on extensive hill sides uses nitrogen fixing trees to "terrace" & ammend uphill)
5) over time there will be no gaps in your living hedge & the up hill terrace will fill in with enough soil that your planting lay out is freed from only in notched basins

Gringojay, welcome to the forum, and in no way did you breach forum etiquette.

I find it interesting that even in the Dominican Republic you have clay soil. My impression of the Dominican Republic is that you can grow anything there, and you automatically have wonderful soil.

I thought about the PVC pipes, but never did use them.

Sammy

Hi sammy,
Hispaniola Island is full of micro-climates.
I own mostly clay on semi-arid north coast, but have potable wells.
D.R. central mountain interior valley is the cool climate export vegetable center. Greenhouse production has really taken off there.
Haiti premier food crop valley is in north central region. Deforestation messed up most rural districts. Container production seems promising for most, who have no land tenure.
Fruit production varies all over Hispaniola & fruits grown must adapt to site.
Fruit export is problematic due to official quotas of buyers' government.
Tropical soil on slopes are leached out & some valleys are desert. Fertilization & insect control obligatory for commercial production.
Agricultural subsidies of developed nations & trade regulations puts island farmers at a competitive disadvantage for many crops.
The Hispaniola Islanders like western foreigners of all colors.

I am glad you are writing, and your response is very interesting.

I teach Spanish in Oklahoma, and we explain culture as best we can without bringing in politics.

To sell your fruits they must be up to the standards set by the buyers. That means you must fertilize and use insecticides, even if that is not what you would choose.

However, in your own yard, you can increase the texture of you soil by composting, and in your own yard, you can develop more fertile soil. Is that correct? ¿Es verdad?

Sammy

Can international growers be certified as organic producers?

Organic growers can use compost and other lower cost ingredients.

Organic produce that is out of season in the U.S. could command a higher price.

The pine fines I bought are close in price to the compost you mentioned.

You might be able to get buckets for free at grocery stores and such. Or kitty litter buckets. Check on Freecycle or Craigslist.

I've got lots of frosting buckets that I need to clean out. Got those for free.

You might try using a row of buckets to create a terrace. Rototill the whole slope. Do a terrace the width of the rototiller. Stick buckets at the front to hold the soil.

Or if you are concerned about resale value, use something a little more attractive than the plastic buckets. Or cover them up.

Alice