The best time to till clay is when it is wet/moist. Tilling & adding compost/organic matl. now will only help you in the long run. Otherwise if you wait you will end up breaking your back trying to till into an adobe brick.
Hope that helps.

My native soil is clay loam to silty clay loam. While I did not have as much trouble as you do, I had some of that chunky wetness in certain areas of the gardens. Adding compost and especially bringing more of it from outside sources helps a lot. Also working in cover crops helps.

What helped my soil the most and fastest was deeply amending the texture all at one time. I did this by adding 3 inches of medium/coarse sand and 4 or so inches of local sphagnum peat moss. I did this in the summer months after things were drier.I mixed all together into and with the upper 7 inches of topsoil. How does it work? Super great. It absorbs water like a sponge and can be worked soon after rains. Your mileage and soil may vary from my experience. I continue to add organic matter and even do some fertilization.

As others have said, best to til clay soil when it's NOT dry. Also best not to till when it's really soggy wet. Somewhere in between is best.

What my DH always did with new beds was to till twice as the tiller can go deeper with the second pass. If you only do one pass there may be large clods of damp clay which when dry will be like rocks.

You've also found that if clay soil is not amended annually (at least) the organic part of the soil (compost, etc.) will be used up and only the heavy clay remains. So frequently topdressing with organic material is essential with heavy clay.

I've reported ad nauseam on this forum about trench composting which I call 'feeding the worms' but I find it works very well with clay soil. In the summer months I bury my kitchen scraps between plants and the worms take care of them. Easy and ensures my worms are well fed so they propagate. The more worms, the more worm castings, and the more fertile my soil. Those earthworms can burrow through heavy clay and their tunnels eventually help to break up the clay. Adding compost regularly also works well if you have enough altho I never have. Using mulch is also extremely important for providing a good environment for worms as it helps keep the soil moist. Worms also like grass clippings so if you have a source of unsprayed clippings they make a great mulch. The worms will pull them down into their tunnels.

After reading about using wood chips tilled into the soil (link below) I've been mixing shredded bark, compost, and alfalfa pellets (as a nitrogen source) into the soil in part of my garden. Still early to assess but I haven't seen any problems yet. Not sure if the shredded bark will act similarly to wood chips but I felt it was worth a try.

Here is a link that might be useful: dig in 50% wood chips

+1 luckygal!
Spot on :)

To determine if a soil is workable pick up a handful and squeeze it tightly and then poke it. If that clump of soil falls apart it is workable, if it does not it is not.
The one thing that will help clay soils is organic matter, enough to make a 6 to 8 percent mixture with that soil. However, adding that organic matter is not a one time thing and it will need to be done every year, just as Ma Nature does. Unless one is ready and willing to add very large amounts of sand, 45 percent according to most soil scientists (Purdue, Michigan State, Wisconsin State, Washington State) to 75 percent (Cornell), adding sand to clay will not be of much help.

kimmsr, I suppose some clay has maybe only 10% sand to begin with. Adding 35% more may get you there. Also adding good peat moss at the same time does the trick for me.. I would not say, "Just add sand."

Adding organic matter is critical and working in green and cover crops is too.

Based on what I have seen, and what the researchers at Purdue have found, the peat moss you added to your clay soil did more then the sand.

kimmsr, You may be right about the peat moss doing more good.... the farmer who has the peat moss says, "Forget the sand." Still, I believe that the combination of the two into a good soil to start with plus lots of added and grown organic matter has produced a dream soil.

I avoid disturbing my clay when wet. Actually if you want a spring garden, amend in fall and let the worms and the freeze/thaw cycles fluff it up for you, then just plant in spring without digging or tilling.

I keep mulches over mine in the hot summer, it keeps them moist and also keeps the pounding rainstorms from packing down the surface. The mulch feeds the soil as it decomposes so I don't have to add a lot of compost by digging. I use mostly grass/leaves mix for garden mulch.

When to till?:
When it is moist but not too wet and soggy. I would also add compost while I am at it : This way you'll hit two birds with one stone, and make your efforts worthwhile. The best time is early spring. This will also aerate the soil for the micro organisms any would pull up some of the leached down nutrients. So as you can see, tilling can serve more one purpose.

JMO

Copied from the most recent KSU Extension newsletter:

"We have gone from very dry conditions earlier in
the winter to many areas being quite moist due to
winter storms. Resist the temptation to work any
soil if it is wet. Doing so destroys the structure of
the soil resulting in clods that may not break down
all summer. To determine if a soil is too wet to
work, grab a handful and squeeze. If water comes
out, it is much too wet. Even if no water drips out,
it still may not be dry enough to work. Push a
finger into the soil you squeezed. If it crumbles, it
is dry enough, but if your finger just leaves an
indentation, more time is needed. Be sure to take your handfuls of soil from the depth you plan
to work the soil because deeper soils may contain more moisture than the surface."

The last sentence is probably the most important, especially in clay.

I know the drill.....been gardening about 70 years. We used to have very large gardens when I was a boy. The lower and darker and heavier soil would clod up some by disking with the farm disk. The other areas tended to be nice and mealy.

When I used to fall plow my gardens, the lower ground would be kind of sugary. The higher end [about 6 inches higher in 40 feet] would be lumpy clay. In between it would be more mealy. Since amending the texture and also the structure, it all works up without clods and is an 'earlier' soil that works up easily and much sooner after a rain.. Raising the level of the soil, helps to keep out soggishness too.

In addition to amending with organic material,I find it very helpful to make tall beds in the fall where early crops will be planted next spring. If weather is unusualy wet,the bed dries much quicker than level ground. Knocking the top off the bed leaves a good seed bed. Potatoes can be placed in furrows between beds and coverd by turning beds into furrows.