Temperature consideration:
A hot pile can reach 150 degrees. You should turn it when the temperature drop under 100 degrees. It means that you may have to turn your pile once a week.

Odor consideration:
If it smell bad. Your pile is in anaerobic condition. You should turn it.

Physical consideration:
A 5'x5'x3'pile weight +/- 3000 pounds.! How ambitious are you?

Good question with many answers depending on who you ask, which book or website you read, etc. Turning the pile once, to get the outer materials into the inside, or even not turning at all, works fine for my wife and myself. We have nine pallet bins now and have discovered over the years that frequent turning is bad for the back, and can cause the compost temperature to drop and be hard to raise again. Lately we haven't been turning at all, unless the ingredients include weeds.

The trick to not turning often, or at all, is to build the pile well in the first place, which is something you'll get a feel for. Building the pile well means aiming for a good mix/layers of coarse dry 'brown' materials like straw, and finer water-heavy 'green' materials like kitchen scraps, so that the pile has both air and moisture built in. Also covering with a tarp in heavy rain or snow to prevent waterlogging.

That does depend on many factors starting with how energetic you are. You can get compost in 14 days, if you turn your material often, or you can wait for a year to get compost if you are less inclined to expend a lot of energy doing that. If turning your compost causes back pain you are doing that job wrong and need to look closely at what you are doing and change how you do that.
Often you will see in the instructions that you would turn you compost just as the peak temperature, around 150 to 160 degrees, starts to drop and if all things are about where they should be you should note a temperature rise again in a day or two, and you continue to do that until there is no more temperature rise. Some other sources will tell you that you should turn your compost every 3 to 4 days and that is based upon the observations that usually that temperature drop occurs then.
Keeping in mind that turning a 4 x 4 pile of compost is moving around a ton of material, how often you turn will depend on how much work you want to do.

Kimmsr, in the same post you make two statements that are, in effect, contradictory:

"If turning your compost causes back pain you are doing that job wrong and need to look closely at what you are doing and change how you do that."

"Keeping in mind that turning a 4 x 4 pile of compost is moving around a ton of material, how often you turn will depend on how much work you want to do."

All due respect, Kimmsr, but as usual when reading such posts here, I feel a mix of 'I should pay heed to advice from this venerable old gardener' and 'This guy/gal is so full of sh*t'. LOL

Turning compost is hard on the back because lifting a weight while leaning forward is a bad idea. The more frequently you do it the more likely you are to want to make it easier on yourself.

I object to frequent turning of the compost pile on more than personal physical grounds. The belief that frequent turning is necessary is part of the mentality that says speed is everything, and too often leads to practices that are, to my mind, contradictory to the spirit of composting, eg. using machinery to blend, shred, mix and turn materials.

I think most of us can afford to wait those extra months for compost rather than use fossil fuels.

Just my two cents.

I have a tiller now and one of it's uses will be to mix my compost. I need to make the most use of the space I have, that means getting the compost through it's cycles and into the growing areas.
One should not feel guilty about using equipment to save physical labor. When My back is out the last thing I want to mess with is a manure fork and a pule I have to reach over to turn.

Hi Jill

How often do you want to turn the pile? I have a tendency to not turn the piles very often. On a couple of occasions I let a few piles go way too long. It depends on my work schedule and what else is happening on the farm at the time. That is not to say I don't dig around in them for I do. I am quite frequently playing in them or the curing bins so there is some mixing going on all the time. This is usually done while the multi-tumblers are being rotated. Heck I've even stood there with a pair of pruners cutting up the twigs, it allows me to turn off my brain for a time, very refreshing.

If the objective is to obtain compost ASAP, then there are guidelines to optimize the turning schedule. If the objective is to take it easy, then as Paul suggests, leave them lie.

I suspect that a lot of people realize that playing with the compost is almost like therapy, it isn't necessarily like work per say. Composting is fun, just go and re-read all the compost whacko threads, we like to compost! We feel good when we have a newly re-piled bin with nice moisture levels and thoroughly mixed. It makes the beer taste oh so good! And when we get a nice high temperature and steam, look out, it's party time!

Paul, I had to laugh at the "contradictory to the spirit of composting" and "using machinery" comment for I immediately thought of golfing for the exercise but using a cart.

Lloyd

I turn my pile twice a year... and really its when I harvest finished compost from the bottom of the pile... I open up the side, and shovel the bottom stuff (finished/partially finished compost) into the wheel barrel, garbage cans or buckets. The unfinished stuff gets turned and remixed as shovel it back into the bin.

Lloyd: I really like your attitude!

Karen

Lloyd, I don't think of it as 'taking-it-easy composting' - it's 'smart composting'. Easier on the back, good for the garden and the environment in general. Besides which, those nine pallet bins of ours make compost for 3/4 acre of market gardens - filling and emptying them is work enough.

You have a great website by the way, imagine growing all those cherries in Manitoba! Do you think Evans would be happy in Nova Scotia zone 6?

In what now seems another life I attended the U of M and fell in love with southern Manitoba, always wanted to go back there. In summer, for sure. If we ever do we'll check out your place.

Sorry Paul, bad choice of words on my part.

Lloyd

Paulns, they are not contradictory statements although they are about two somewhat different things. If you choose to turn a compost pile and turning that pile cause back pain you are working in the wrong way, you are doing something wrong, your posture is incorrect, something like that. Anytime you do something that causes pain you are doing it wrong and need to correct the way you are working. Many times I will see someone bending from the waist when shoveling instead of keeping the back staight adn bending at the knees, and that will result in a sore back because that is the wrong way to do that.
Tilling soil is a lot of work too and, along with not turning my compost anymore, I don't till either, except when planting something new. But I know the proper way to bend to pick up heavy loads and I know not to twist with a heavy load, and I always warm up with some stretches before doing stuff like that and many people do not, resulting in back pain.

Good question, loveofmylife! Aren't you glad you asked?

We may disagree on these finer points but basically we're on the same page.