I put a wire hoop around mine, maybe 3-4 feet tall, and that supported it enough. The stems got pretty thick, but I should mention I do NOT have high winds, hardly ever.
I suspect that soggy feet in winter did mine in. That bed is somewhat low-lying, or rather that part of the yard drains worse than most. The only place to cut a drainage trench for that bed would be on the neighbor's property, and I haven't negotiated for that (yet). I have a LONG to-do list for when I retire!
Oberon46 said:... Could you tell me again how you break up hard pan clay. A friend moved out to the valley and her house is surrounded by what might as well be concrete. Cannot dig in it.
Well, there ARE types of clay even worse than what I'm familiar with: I've read about "caliche". I hope that "hard pan" is not caliche. But if it is "just normal clay", or "compacted clayey soil" ...
I think of it as two problems.
- True clay needs to be "diluted" with organic matter and silt or fines. Good loam should have less than 30% clay. If you can add two parts of soil amendments for every one part of clay, pulverize and mix everything, you can have great soil overnight. But that's expensive! Maybe there are ways to get by with less compost and other amendments until plant roots and worms create stable, aerated soil.
- Not everyone agrees, but clayey soil benefits from added grit and coarse fibers. They form a "support scaffold" to hold open larger air spaces.
1.
Pure clay and clayey soil need to be "diluted" with organic matter, fines and silt.
As it is, pure clay is too hard when dry for roots, but too sticky and flowing when wet to maintain any kind of open space for aeration.
Mixing it intimately with compost, raw materials for compost, silt, or fine sand makes the clay less sticky and more friable and a LITTLE more open.
However, when clay is soft and "flowing" or tends to slump down, it can't support air spaces. The clay oozes and flows into each crevice or pore and fills it - like sealing a jar airtight. The clay becomes anaerobic again.
For example, suppose you roto-tilled a bed and reduced it to small "clay balls" with air space between each ball. Because the clay is soft and pliable, each ball deforms to allow the bed to subside. The air spaces shrink in size. The clay is probably soft enough to flow further into remaining voids and squeeze ALL the air out!
My theory is that fine sand or other grains or fibers much smaller than 1 mm
mixed well into the clay give the clay phase itself a little stiffness - hopefully enough to slow down the rate at which clay slumps and subsides to fill in air voids.
They also make the clay clods less sticky, so they don't weld together as soon as they touch each other while moist.
When the clay is "diluted" with compost, it also becomes more friable so you CAN break it up into tiny clods and mix it with amendments. You can till it ("fluff it up") to mix air into it like an omelet. You might have to "fluff it up" again each year or after each crop, for a few years, until you repair the clay even further. I firm it down SLIGHTLY again after fluffing it up, hoping to form a stable matrix with some air spaces, that will survive being rained on.
(Always add some mulch on top of clayey soil, or rain will pound the surface into a mud-clay-slurry which it will dry into an air-tight clay crust.)
Therefore: first, second and third: add lots of compost. As much as you have or can afford, say up to 50% on the first round.
Bark fines, unfinished compost and other finely divided organic materials are almost as good as finished compost for mixing with clay. Even sawdust or fine wood shavings might be added if they've been composted first, enough to minimize nitrogen deficit.
If you can dig up the clay and till the compost in well, mixing it finely the first year and "fluffing it up" then firming it while semi-dryish, you might save a year or so in reaching loose, open soil.
If you don't have enough finished compost on hand to put down a 9" layer and then till it under 18" to make an 18" deep bed of 50% compost / 50% clay, no problem. Add what compost you have, then cover it with as much organic mulch as you can afford. Even wood chips will decompose over time and add OM to the clay.
And/or sheet compost in place.
Or use the future site of a raised bed as the current site of a compost heap.
If you have to layer the compost and mulch on TOP of the clay because it'/s too hard to work, that's OK too, just wait for rain and worms to carry it down into the clay over months and years, to loosen it enough that you can turn it over NEXT year or the year after.
Patience is easier than deep-turning hard clay! But it takes longer to turn the hard clay into loose, open, aerated, fertile soil if you wait for the worms to come and then get busy. Many people swear by no-till methods, even for creating a new bed from clayey soil.
You might be able to grow for one year in the layer of compost on top of the clay! At least some kind of cover crop like buckwheat or anything with lots of roots. Clover?
A "Lasagna style" bed would call for a very thick layer of newspapers, or 1-2 layers of corrugated cardboard laid down first. That is said to suppress weeds or even grass, and attract worms. Then lay the compost and whatever else you have on top of the cardboard. Then plant right in the compost. (I would watch it closely for slugs. It sounds like Slug Heaven to me, but I haven't tried "Lasagna style".)
2.
When the clay IS soft enough to dig, my approach differs from many people's.
Some say that adding coarse sand or grit or bark fibers or composted wood chips to hard clay makes concrete, but I see it differently.
I think the grit adds air spaces
*IF* the amount of compost is almost adequate. A little grit provides more structure and aeration when you don't have a lot of compost.
I like to add 10-20% coarse stuff (grit, bark, crushed stone, or sandy or gritty sub-soil), and mix that somewhat with the clayey soil, so that the coarse grains, chips, shreds and fibers help support air spaces mechanically.
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Clay without enough compost is hopeless whether you add grit or not. It's either a pudding that turns to rock when dry, or a gritty pudding that turns to concrete when dry. Same thing.
- Clay plus literally 50 - 70% compost, renewed every year, might not NEED any more help, but who can add 6-8 inches of compost every year?
- Clay plus only 20-30% compost does NOT maintain open air spaces. It slumps, sticks, flows, welds together and squeezes the air out like it was toothpaste in a tube.
However,
I think, clay mixed well with 20-30% compost , PLUS another 10-20% grit or grit-sized bark has MUCH better aeration than clay + 20-30% compost with no grit.
And grit lasts forever, or bark lasts 3-4 years. Now you can maintain the soil by adding less compost every year, because the clay has a lattice of grit and fibers to support open air spaces.
The added grit also makes the clay balls easier to break up and keep separate (more friable, or at least less sticky). Sometimes I think of fine sand "dusting" tiny clay balls like confectioners sugar keeping sticky candies from sticking together.
