If it's hot and breaking down now, it should be ready by April or May. Two weeks before you're ready to plant, whether the compost is finished or not, fork it into your soil down to a depth of a foot or so. You could pull out any really big chunks and leave them to compost in a corner of the garden.

I would try to work it in earlier than 2 weeks before planting, if possible, but other than that, I agree with nygardener. I think you'll be OK if the compost is most of the way there, and you get it into the ground early.

When raw organic matter, unfinished compost can be considered that, is mixed into the soil, tilled in, the soil bacteria will go to work on that to finish it which will tie up most of the available Nitrogen in the soil. When those bacteria are done that Nitrogen they tied up becomes available to the plants again, but that could take 6 to 8 weeks, not just 2. However if unfinished compost is layed on the soils surface as a mulch the same thing does not happen, so unfinshed compost could be used as a mulch on a planting bed, if necessary, although it would be better to allow that compost to finish before applying it to your garden.

Here's a doc on compost. Read the part about curing and I think you'll understand more about what you can get away with. The biggest problem I've seen is with seed germination. Transplants have a much better chance dealing with it.

www.calrecycle.ca.gov/publications/Organics/44200013.doc

If you have really healthy soil, you can push the envelope. After experimenting you'll learn how plants respond to levels of uncured compost and how to help them along. Limitations only make us more inventive.

I have sheet composted in the fall & spring for years now.
I plant year around & never had a nitrogen problem, would not know what one was if I did not read Organic garden books.
Ether this is a mole hill made into a mountain or I am a super gardener.
I think sometimes people over react to thing they read.
I go by what I know, what I see & what I personally can prove or seen other prove.
So far I give away fruit & vegetables every year.
That is my rule of thumb
Prove it or not, if I have to give crops away then I must be doing something right.

The article from shebear is very good IMO. It explains things quite well.

Nitorgen immobilization is seen more often when a high or very high carbon content material is incorporated into the soil. Bacteria prosper in the 25-40:1 C:N range with 30:1 said to be the optimum. If the incorporated material is in the 'good' range then immobilization is not as likely to take place. This is why there are often recomendations not to till in straight leaves or sawdust as an example.

Phytotoxicity is a different matter than N immobilization. This is refering to organic chemicals released during the composting process. These organic chemicals can inhibit seed germination and seedling growth. One of the tests for mature compost is a germination test.

And then there is oxygen deprivation. If larger amounts of easily digested materials are incorporated into the soil, organisims will go to work as fast as they can to digest these materials. They will consume a lot of oxygen to do so just like they do in a hot compost pile. This may be detrimental to plant roots.

Lloyd

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If you're turning the compost once a week it will be done long before April/May. Just keep it moist and you'll see that when you're turning. It'll dry out fast in LA.

I bet you could plant sooner than April in LA too. Next time you're in a book store, check out the 'Sunset Western Garden Book' and look up your zone. You've probably got a 10 month growing season.

Mulching unfinished compost on top will be real handy keeping that sun baked ground moist. It will break down rapidly so get ready to find something else to mulch with after that.

too sense
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to sense
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jolj, I think the very fact that you're sheet composting probably helps. As I understand it, nitrogen immobilization is a problem when (as Lloyd said) carbon-rich materials are worked into the soil. I also understand that sheet composting involves placing compostable materials in layers on top of the existing soil.

If the unfinished materials are on top of the soil rather than in it, the nitrogen problem that everyone is worried about isn't really a risk. As for whether the risk really is a molehill rather than a mountain, I really can't say...but I think your situation is a different one, anyway.

I never till in or "turn in" anything. I just place it on top of the soil as a mulch and it works well. Tilling can disrupt soil life and cause erosion. I often mulch with unfinished compost, especially when doing lasagna gardening or interbay mulch.

Karen

Here's a question whose answer might be exactly what ladon needs to know: if you turn partially finished compost into the soil, could you supplement the organic nitrogen levels with, say, a handful of alfalfa or cottonseed meal per plant to offset any possible nitrogen deficiencies due to bacteria? Would this create any undue or damaging heat to the root systems? I use hair (for the nitrogen) from a local barbershop to help cook my compost. It's free and WEED free! I do use a handful of rabbit feed (alfalfa) under my veggies when I plant and it works wonderfully (except my peppers; too much nitrogen!) but I've never tried it with partially finished compost.

Ladies and gentlemen, the writer, lives in California and is planting VEGETABLES.. NOW....not in April or May like us up north so what she is asking about is 'can she use the unfinished compost she already has...on her vegetable plot.

The articles on using "unfinished compost" points it out well. For a mulch, sure go ahead....for vegetables..NO WAY.
Of course the finished/unfinished is separated...that's done as it occurs and the finished, to the extent you have it is usable. The unfinished should be left to complete the breakdown. Where its necessary to amend the soil with compost, buy some commercial composted cattle/sheep manure and use it.
If you value the vegetables for what they will become and for what they will do for your table, then don't use the unfinished compost.
You put too much effort and care into a vegetable plot to have it ruined by simply giving it something it can quite well do without.

Ladon, do some research also on the types of vegetables you plan to plant. Some resent being given nitrogen...which compost can supply in quantity. Given compost they could suffer badly--turn up their noses at it and come to nothing. Others welcome it.

leira, I think you are talking about lasagna composting.
I am talking about spreading manure on a field in a "sheet" them cut it under. Then planting the next week or in 4 month.
This form of composting was used before the fathers of today's Organic Gardening even new about raised beds & compost piles. You can also use a middle buster(plow) to open up a row & put the manure in the trench,then use a side baster to cover the manure up.
kgcrna there is no water or wind erosion if tilling is done right, at the right time. As for the circle of life, I have no problem with tilling, it kills bad bugs (up to 90% in some cases) & no one has proven to me that they can control invasive plants with out tilling or digging. So if you have a perfect plot with no invasive plants, then good for you.
But some of us have them, but that is another thread.
shebear, I totally agree, Thanks for the link.
pt03, As I have said before, your....compost does not stink. I always give leave matter 60-120 days to rot after turning.But I have turned grounds & chaff in the mourning &
planted in the evening. I know that greens on the top of the ground pulls less nitrogen out the soil, but it rots faster in the soil. With my Balance soil, I have no problem with nitrogen immobilization, so far. But I would not want to lead a new gardener with what works for me.

The only problem I've had using unfinished compost is volunteer squash and cucumber popping up, that I didn't realize until too late, and crowded out the squash and cucumber that I really wanted to grow.

Well, jolj, I looked up the definition of sheet composting before writing, but I guess I didn't read enough different ones to get a consensus -- because the ones I read said nothing about turning it in. Oops.

My understanding, which also matches my experience, is that the biggest concern would be with germination. I find germination shortly after working stuff into the soil to be a little bit fragile, though transplants aren't a problem. I would personally be concerned about the "1 week" planting, but probably not at all about the "4 month" planting.

Sorry, to be clear the one week is used with the trench & the sheet was months later.
The sheet as in covering the whole field, then cutting it in.
This is a garden booklet.
... make compost in 14 days by Organic Gardening Magazine.
Sheet composting for large-scale gardens
"The conception of sheet composting grew out of the needs of organic farmers and large-scale gardens. These people found it too difficult and time-consuming to construct the compost heaps necessary to maintain the fertility of large acreages, and so necessity again became the mother of invention. Instead of composting in heaps, organic farmers began spread compost materials directly on the soil, in raw form, the turn them under to compost right where they were to be used."
I agree with your concern on germination. It is hard enough to get a good stand without damp off, cut worms, without adding rot to your problems.
Sorry that I was not clear.

Ladon

I agree with almost everything that has been said above, even though much of it seems contradictory. I think that shows just how complex gardening can be. Several people have alluded to the fact that it all depends on what you plant. If you want to plant some of the really tough plants like kale, turnip, okra, etc. I might say work it in. But if you want to plant some of the more sensitive crops like lettuce, I would not. Crops like tomato and potato evolved in the deserts of Peru. They have not had much time to develope defenses against the fungus and insects that will be encouraged by unfinished compost. It all depends on what you plant. Without seeing how far the compost has decomposed and without knowing exactly when and what you want to plant, it is hard to say.

Here is a link that might be useful: Building Up Soil

Wow....lots of info, everyone. Thank you for all of your input, particularly for the referenced articles. They were very helpful. The main thing that I will be growing in my garden is heirloom tomatoes. I've been growing them for 10 years, experimenting each year with different growing techniques, with greater or lesser results. This is the first year that I am composting my own materials, although in past years I've used compost purchased from garden centers. I began my pile back in November. As it stands now, most of the organic material has broken down. When I turned the pile this past weekend, the bulk of the identifiable material remaining included some pine needles, twigs, and a a few leaves still in tact. Most of the leaves, straw and other materials were well progressed in their breakdown. But, for tomatoes, whose production is very sensitive to levels of nitrogen, how should I approach using this compost? I don't want to make any collosal mistakes by adding material that will provide too much nutrients or take any away? I love my tomatoes to much to screw it up because I got over zealous.
Thanks again everyone...
Don

At the risk of stepping in a mine field.
My brother uses dry, but not rotted manures in the row with his tomatoes & beans. He made a good crop & no one in the family got sick.
I always compost first, so the humus is in a usable form.
According to the University of California tomato is native of western South America. The wild cherry tomato form of the cultivated species, has spread though out Latin America & the Old world Tropics. Late into European, about middle 16th century.

Don
The crazy thing about gardening is that some years almost anything will work. It is the bad years we worry about; heavy rain, fungus, hail, drought, insects, etc. Infected manure is difficult to determine by appearance alone. So we go to great lengths so the odd years do not wreck our gardens. But like jolj relatives, I too have taken short cuts and had good results some years. But then other years those short cuts cost me some tomato plants. We cannot always plan to perfection and sometimes shortcuts are necessary. Putting in some compost even if it is not ready may be better than no compost if that is the only other choice. Our posts are basically an attempt to communicate the risks and options, but it is up to you to decide how much time, labor, and money you want to expend to prepare for an unexpected bad year. Unfortunately, even the best preparation cannot guarantee success. Nature is so unpredictable. Good luck.

I don't believe that it's the so-called tie-up of nitrogen that is the issue with using unfinished compost, it's the fact that unfinished compost contains several organic acids that prevent germination of seeds and inhibit root growth. Oxalic, butyric, acetic, and other intermediate stage compounds that are on their way to becoming humic and fulvic acid. It takes time.

Yes, your compost might look like it's done, but I would recommend leaving your compost off of the garden until the plants are established. Turn the compost and pile it up. Later in the season your plants will likely tolerate the unfinished compost better, lay it on top of the soil. Don't till compost into the soil, use is as a mulch.

Compost is a weak fertilizer and is considered more of a soil conditioner than a fertilizer.

I really wish I had a good sense of "how long is long enough." One interesting thing here is that last year I asked a very similar question about working not-quite-finished compost into my garden, and folks said, "sure, go ahead!" People on this thread seem to be a lot more cautious, however.

In the ideal world (or my own ideal world, anyway), I would have added compost and such in the Fall, at garden clean-up time, and then I wouldn't really have any concerns about the soil being ready by Spring. Or, at least, I would have given my compost bin a couple more turns, and ensured that one of the bins was "finishing" and wasn't getting anything else added to it by helpful household members. Sadly, I missed that boat again this past year, and I was hoping to get a Really Early Start, as soon as the ground could be worked. However...I'm staring at a garden covered in much-deeper-than-usual layer of snow, so I've got serious concerns about my ability to amend my soil any significant amount of time prior to my normal planting time. I'm actually slightly concerned about being able to plant at the normal time at all!

So, yes, I know that "it all depends" when it comes to how long it will take for not-quite-finished compost to be sufficiently broken down, or to be more science-y, for various intermediate compounds to finish transforming into humic and fulvic acid. However, can anyone offer any guidelines on how long might be long enough?

I used to cure my compost for a long time, and then screen it. Now I use it unfinished as a mulch because I run out of room in my 2 bins
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None of my plants seem to mind. I do think this is a mole hill made into a mountain.

After years of mulching with unfinished compost

Tomatoes
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This was those same wintersown tomatoes when planted out in May
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My flowers don't seem to mind, either.
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I fertilize very little. If I remember I use a little organic stuff in the planting hole. Rarely do I use any more fert for the life of the plant.

Karen

If the organic matter you started with is manure, I would be sure to wait 90 days from when it was fresh for harvesting vegetables and cooking them and 120 days for harvest vegetables and eating them raw. Any other type of organic matter, I would work it in, wait at least a few days, and plant tough plants that can handle a less than ideal environment (kale, turnip, okra, peas, beans, etc). If you plant lettuce, tomato, potato, or some of the other more sensitive crops, they may not do so well. Perfection is not always attainable and some corners can be cut.

Here is a link that might be useful: Building up Soil

What is that saying?
A pic's worth 1000.00 words.
Thank you, kqcrna, nice pics, good job.

GreenGarden makes a good point, though. If I were using manure and using it on food, I wouldn't be so quick to use the compost. Here in suburbia, manure isn't a common ingredient. And I don't compost any poop, including dog or cat.

Karen