If you can shred them, use them as a mulch. But intact cones don't decompose easily, and you would end up with clay soil with lumps in it.

What you need to do is lay a really THICK layer of easily decomposed stuff onto the clay area and keep it moist. Plant some clay-tolerant cover crop and let the roots penetrate the soil to loosen it. When you cut the cover crop, the roots stay in the clay, decompose abnd create lots of tiny channels for aeration and drainage.

Oh, that's a great idea. Thanks! Anyone have any ideas on what a good cover crop for clay is in zone 3?

Clover is good. It worked for me to break up my clay soil. The problem is clover produces lots of seeds (literally millions) so it might "jump" to other areas of your garden. The good side is that the root can penetrate deep into the soil even during the winter. It is said that they can "dig" 4 feet into the soil!

If the clay is not too hard, you can use oats (it's an annual). Sow them one to 1.5 months before your frost date. It will grow tall enough but not set seeds yet. Then the frost would kill them. Next year you can cut them down, mix in with the clay a little (some people say that such mixing is not even needed), and you can grow on them.

After a couple of years, you soil will improve greatly.

You can search the net for "green manure" or "green manure for clay soil."

If you have enough pine cones they could make your clay soil better, given enough time. Cover crops (a cover crop is any crop you grow on a soil to aid in stabilizing that soil, ie. preventing erosion), or green manure crops (about the same thing) can help as can adding lots of organic matter from other sources, compost, shredded leaves, etc. How well cover, or green manure, crops will grow in your clay soil depends on how well that soil drains now and the soils pH.

Better not handle those cones, they have a waxy coating that will act like glue. Wear gloves.
But, you used the word "condition", and pine cones, while slightly acidic, wont change a thing to your soil's acidity, there's just not enough influence by its being there.
Instead, look up some research on "gypsum"--see if it could be of use in your soil.
There are many 'conditoners' that can change --some practically overnight--a soil's pH; notably garden sulfur.
But changing your clay soil's pH is not going to change its structure; its ability, good or bad, to retain moisture; that has to be done by changing how the clay soil holds onto too much moisutre in the wrong places.
Gypsum might be able to help in that regard.
Otherwise, an amount of organic matter, chewed up and injected into the soil, over time, will do somethng for you

Thanks everyone for the help. I know so little about this that I see I used the wrong word. It is the structure I'm dealing with, not the pH. As far as I know so far anyway.

Couple questions....

If I add gypsum can I do that and plant at the same time? Or do the gypsum and plants have to be time separated?

If I go with the oat solution, where do I get a very small amount of oat seeds?

As for clover, what is that? I only know the tiny three leafed kind that you occasionally find four-leafed ones in.

I have a bed in the back that has been dug up and amended but only to about a foot. It has mostly perennials growing in it and they're doing okay but not great. If I try to improve it through oats/clover/gypsum/etc. what would be the best way to go about that? I'm guessing I'd have to move the plants to pots for awhile or something? Clematis, black bugbane, tickseed, and goats beard is what's in there now; along with a few annuals.

Crystal

IF your clay soil is sodic then using gypsum can help, but if your clay soil is not sodic (highly unlikely in zone 3) then spreading gypsum will be largely a waste of your money, time, and energy. Your clay soil needs organic matter, lots, enough to make up between 5 and 8 percent and the pine cones can be part of that. With about 500 Red, White, and Austrian Pines, Blue and Black spruces growing in the windbreaks around the property I do not get enough cones, even if I picked up every one, to begin making a significant difference in my sand.
I have used them, sometimes as a deterent to slugs but even that takes a bunch.

I'd do my research before adding gypsum: it only really helps in sodic soils, which are pretty rare.
I love cover crops. I have a winter mix of daikon radish, cereals, fava beans and lupins at the moment.
Daikon roots are huge and it's a great clay-breaker. Chop everything down before the seed ripens and leave the roots in the ground and the tops on the surface for mulch.
Throw any organic material you can find on there. Mulch will do more than pretty much anything to loosten clay.

Hi Crystal, I'm in zone 3b in Canada with heavy clay soil so we might be in the same province! I've never used pine cones as we have mostly spruce and fir here and their cones are too much bother to pick up. If you ran the pine cones thru a shredder they'd make great mulch. If you mix them in they'd improve the soil over time but you'd need more nutritious organics as well. The pine cones would improve the texture and drainage though.

When I first started gardening here my DH tilled in sawdust, mushroom manure, cattle manure, and I planted a cover crop which was later tilled in. It was a blend that our local farm/feed store made up that was field peas, vetch, and annual rye. Our feed store sells various seeds in bulk so one can bag as little or much as needed. I also continued composting everything I could. The key is to keep adding organics continuously and over time the soil will improve. The good thing about clay is that it holds moisture and nutrients well so once you get it past that concrete stage it will be easier to work and your garden will do well.

We've always tilled organics in when starting a new bed as I think it's faster than just piling on the mulch. I know the worms can move thru the heavy unamended clay but one really can't plant in it and expect most plants to do well. My DH always goes over it at least twice to mix the soil/amendments as deep as possible. Then I expect the worms to aerate it deeper and I do everything I can to feed those little workers.

Before you pot up all your perennials you might try using alfalfa tea as a fertilizer/soil builder. I also bury kitchen scraps between my perennials which feeds the worms and in turn their castings feed my plants. Also if you mulch your perennial beds with a blend of grass clippings and mulched leaves it will really help as the worms love both of those and your plants will have the benefit of mulch.

I've never used gypsum as I don't think it's recommended for this type of clay. I also avoid sand. Lots of organic matter is the best for clay soil.

Great information. Thanks everyone.

What does alfalfa tea do? How do you prepare it?

Alfalfa, compost, or manure teas will not help make a bad soil good, that will require organic matter. Those things may be of some use for the first few years you are trying to make soil good but spraying them around soils with too little organic matter will really do little since there is nothing for the bacteria that grow in them to live on once sprayed on the soil.
Spraying Alfalfa, compost, or manure teas on soils with ample levels of organic matter, early on, may supply more of the microbes that are just starting to develop in that soil.

Crystal, It's a huge job to dig and improve heavy clay soil deeper than 12" and something I've never considered necessary except for some trees. Of course if you have plants with really deep roots it may be worth it altho most perennials do fine in that depth.

The alfalfa tea will help to feed the plants so they have a better chance of surviving while you are improving the soil with compost and mulch and by burying organics between the plants. I think it also makes the soil more habitable for the earthworms. Every perennial I dig up has many worms in the roots. While I don't know a lot about the life of earthworms I think they probably eat any roots that decay and perhaps also eat healthy roots. I expect the alfalfa tea helps to develop a healthy root system. Anyhow I know the worms don't hurt my plants and their castings are one of the best fertilizers so I like to encourage and feed them and the alfalfa tea feeds both plants and worms.

I know some people don't agree that alfalfa tea is very useful but I really like it and don't use a lot of other fertilizers. My plants seem to be healthy and I have few garden problems so something must be working! Alfalfa pellets can be purchased at your local farm and feed store and are quite inexpensive.

There are a lot of recipes for alfalfa tea which you'll find if you google. I don't follow those recipes as many recommend epsom salts which I'm not sure is necessary in my soil. If you know your soil is deficient in magnesium it would be helpful altho many recipes seem to use what I consider too much. Also I use the tea very diluted and more often than most recipes recommend.

To make the tea I put a few cups of alfalfa pellets in a 5 gallon bucket and fill bucket half full. Stir, or blast more water into the bucket with the hose every day. This aerates the tea. I just bail out about 1/2 quart and add it to water in my watering can. I keep adding water to the bucket until what's left looks very diluted then I use it full strength. The residue left in the bottom of the pail can be composted but I usually put it around the plants. Some people think the tea has to stink to be good but I prefer to aerate it sufficiently so it doesn't. Mine smells like alfalfa hay that's slightly fermented and not at all unpleasant. For some plants that are growing vigorously I water with diluted tea almost every time I water.

You can add sand, but you will need 50%- 75% to make any head way.
I live in every sandy to sandy- loam soil & am adding clay to some beds to hold water & nutrients.
To bad we can not trade 4 dump trucks of soil, that would help us both.
Best to add compost & newspaper to your beds.

I use pine cones as a base for the plant. Let me explain, I make a hole and layer the pine cone on the bottom 1-3 cone high, then add soil, and then the plant, then more soil. Oh yes, water it and call it a day. This will provide some drainage and the plant will gobble it up in no time.

True & the compost from the cones will enrich the soil.

And the plant's rootball will sink down into the soil by the same depth of the layer of the cones, leaving the plants growing in indentations. That is really only an issue if you fill in the indentations as then the plant will be buried too deeply.

Pine or other conifer cones provide negligible nutritional impact to a compost and are slow to decompose if left intact. It would be a far better use of this free material to grind or chop them up and use as a mulch.