Here's the little I know. Unfinished compost can inhibit germination when mixed into garden soil. So it's best to blend it in during the fall months. During summer growing it does well placed on the surface more like a mulch. If it's already mixed in then it would be fine to set out plants as germination is no longer an issue.

i have always been told the opposite: get compost IN the ground cuz it will lose a lot of its nutrients if left in the open.

the middle ground for this is to put the compost down on top of the ground and cover it with a mulch....

I do both. I amend every planting hole I make with lots of compost, FINISHED COMPOST. Dig a much larger hole than you need, fill the hole with a mixture of compost, soil, optional fertilizer. Pack it down and then make a smaller hole for your plant. Top dress everything with compost. I don't till, but if I did, I would till finished compost into the soil. For seeds, plant into a bed amended with finished compost. Compost is finished when there is very little material recognizable as the original stuff. A few twigs or some clumps of partially decomposed leaves are OK and can usually be shredded to dust by rubbing between your hands but is not really necessary.
Bill Hill

Unfinished compost can inhibit germination when mixed into garden soil.

Wow, ok, that explains the troubles I've been having. I've had a hell of a time with germination. Transplants do ok, but seeds don't want to sprout in my beds.

Time to lay off adding compost.

Thanks so much for all your comments. I guess the big issue now is determining whether compost is "finished" or not.

The nutrients in compost are very stable so when compost is applied as a mulch to your soil there would be no nutrient loss to the atmosphere. Since tilling soil at any time can damage the structure and since the Soil Food Web will work that compost in much better than you could with a tiller, tilling compost in is not necessary, you could but it is not necessary.
If compost is finished you would be able to plant things directly in that compost, as I do in pots, and no harm would come. Sometimes with unfinshed compost the soil bacteria will work diligently at digesting that unfinished compost and would utilize the majority of available nutrients so they would not then be available to your plants which then would not grow as they should. So you could use unfinished compost as a mulch unless it is still being actively digested and is hot.

jbann - "Unfinished compost can inhibit germination when mixed into garden soil."

References please?

http://www.compost-info-guide.com/using_compost.htm

I should explain. This year after coating the entire garden with an inch of "almost finished" compost and scratching it in I proceeded with planting. Spinach didn't germinate, neither did radishes, beets or lettuce so off I went and bought new seeds and replanted. Same thing, although two or three seeds made it but the plants looked awful. A bit of research 'Google' and I found my mistake. I thought the soil had some horrible disease or nematodes or "something wierd." Hope this helps.

jbann23 writes Hope this helps.

Your little pearl of wisdom has been one of the most helpful things I've read on these boards. Thank you.

Ok, now that I've had a chance to read what that link that jbann23 cited has to say, I don't believe their explanation. My plants are showing every sign that I have high levels of Nitrogen in the soil; bushy growth. The potatoes bolted, the tomatoes are bushes, the corn has sprouted two or three suckers each and is tall and bushy despite being crowded.

That web site, claiming to be the best compost information on the web, says that the seeds don't germinate because of a lack of Nitrogen in the soil. Sorry, but seeds don't need anything to sprout except water. Seeds will sprout in a wet paper towel. No Nitrogen there.

I think that newly sprouted seeds are vulnerable to attack from the same bacteria that is living in the compost. Especially if you are planting in warm soil; levels of bacterial activity are closely related to temperature.

In nature the seeds are in the soil/litter for the entire winter and get a chance to germinate before the soil warms up enough to encourage bacterial growth in the litter. It's us gardeners who are trying to germinate seedlings well after the soil has warmed up.

But the bottom line is; don't plant in compost unless it's dead compost. Everybody extolls the virtues of live compost; how the bacterial community deters pathogens and pests, and how the plant lives in symbiosis with the microfauna. But nobody seems to make the connection between compost bacteria and seedling mortality.

What I think I'll do in the future is try to find some soil underneath the surface of the garden bed that has no visible compost, bring that to the surface, and plant seeds in that. Once the seedling has sprouted, its roots will grow out of that non-compost soil, into the compost soil and make the adjustment to life in the organic garden.

Seems like someone would have noticed the problem with seedling mortality and come up with seeds that tolerate live compost. Oh well. (And, so much for all the self-anointed 'experts' and their theories about compost and seed germination.)

Idaho Gardener - the nitrogen starvation is only temporary and in a short time, maybe a week to three, the nitrogen is restored to the soil as the micro-organisms finish things up. But still, your take on the situation has a lot of merit. Indeed the soil resumes it's ability to feed plants as it should after the breakdown is complete, hence your success after a time has passed. Thank you for your comments, happy and successfull gardening.

jbann, fyi, my crack about self-anointed experts was not aimed at you. You have been very circumspect about offering advice.

My bile comes from seeing (and getting caught up in) the many fads that seem to sweep through the gardening enthusiast community. Seems as if I have too much compost in my garden beds. I'd never even heard that it could happen, but I've managed to do it.

I have been dumbfounded by the lack of germination of certain vegetable seeds in my beds. I thought that I had done everything, and done it well. Apparently, I have done things a little to well. Only transplants and the hardiest of vegetables are doing well in my garden beds.

I had planted some carrot seeds back in April. Well, they have sprouted this week. That's only 10 weeks to sprout a few carrots from the many seeds I'd planted. And the peas, which virtually grow themselves if you give them a chance? They are off to a very slow start. Sheesh.

I'm still learning.

It is probably fungus in compost that inhibit seeds germination. Usually even weeds don't grow on compost piles of 1 year old.

I had trouble w/ direct seeding and germination. The stuff the did best were the big seeds, like Corn, cucurbits, sunflowers that I planted by forming a ball of seed sowing mix around them and planting the whole thing an inch deep. The small flower, lettuce type seeds that I put on top did almost nothing.

The Importance of Compost Maturity

This is one of the reasons I allow my compost to cure for an extended length of time.

Lloyd

Penn State has a good article on determining if compost is "finished" and a seed germination test is described in it. The problem isn't nitrogen but phytotoxic compounds (they don't describe them) that are present in compost that isn't mature. It's an interesting article and may answer some of the OPs questions regarding use of compost. Link to the article is below.

Sandy

Here is a link that might be useful: Quality and maturity of compost

Sandy, that was really interesting. Thanks for the link.
Fanfortony

Canadian site talks about "organic acids" in some intermediate stages of compost and oxygen deprivation.

Lloyd

I have a lot of fun using compost of various "vintages" in different ways. The most finished, perfect black compost goes wherever I need more good organic matter, even areas planting directly into it, the veggie garden areas, or maybe around my roses. The sorta-composted stuff, that may still have identifiable bits of shredded leaves and pine needles, I use as mulch around vegetables or shrubs. I may place layers more than once during the season so it does not put too much moisture or breakdown heat around the plant stems. Compost that is really not ready, and maybe a little ooky but still far enough along not to contain identifiable stuff (veggie peelings, etc) I may place at the edge of a bed I am expanding, or an area that needs improving and doesn't have much planted. I might cover that stuff with more finished stuff to look better. Whenever I have a lot of shredded leaves or appropriate grass clippings, or sometimes other small organic stuff--sweepings from under a cedar tree--I use a lot of that directly as mulch or a form of sheet composting.

The reason I do this is because it helps me keep all kinds of organic matter, from yard waste to kitchen waste to cardboard and paper, moving through stages in the various areas I have to contain or corral it, and keeps it moving into the garden areas AND cuts down on the need for another type of mulch. I use closed garbage cans for kitchen waste composting, and in the summer with lots of green stuff growing they fill up faster than they break down, so as soon as it's not critter-attractive, I need to dump it and let it finish off, either in my open pile area or in the garden somewhere. I often don't want to mix newer compost with older, so I will look for a way to go ahead and utilize it in the garden; or, if I am collecting a material is already essentially like a fine mulch, it's less hassle to just place it directly into the garden than put it in a bin or pile and fork it out later.

Plus, it spreads out my composting chores into more freqent, shorter efforts rather than marathon digging and spreading events, which works better for me as form of ongoing exercise. plus gets me out in the garden to inspect and enjoy different areas more frequently.

Steve Solomon in his books when he talks about composting maintains that the soil can't do two jobs at once. That is, it cannot finish your compost while at the same time feeding your plants. He further explains that in his days running a seed retailing/wholesaling/trialing business, most customer complaints of failed seeds were from people sheet composting in their seed beds while trying to sprout seeds at the same time. FWIW.

Wow, I've never heard so much misinformation and false assumptions in a thread on any forum as I have in this one.

compost loses nutrients when left exposed? ... where do they go?

compost inhibits seed germination? ...tell that to all the plants that grow in my compost pile...

there is a difference between live and dead compost? I don't even know how to respond to that one....its the microflora and microfauna that make compost a great soil amendment... whether its finished or not...

Soil can only do one thing at a time? Like its a left handed pitcher with sore thumb..

Much of what is happening in your soil and your compost is simply biology and chemistry... its not magic...

"simply biology and chemistry"

Just great! Two classes I slept through!

Lloyd

Pardon my butting in, but kimmsr, I thought one was not supposed to use compost in container gardening. Other posters have said it before that compost is supposed to be used in the ground and not pots bz of some problem of the micro ....something. Cannot remember..I have been waiting on my compost in a bin now, hoping to use it in my potted veggies, but haven't done so bz of all the various don'ts and dos. Please tell me..Thanks!

joepyeweed, you'd better do some more web searching before you characterize other people's information as misinformation and false assumptions.

You say that compost does not inhibit seed germination? Do a google search on the terms "phytotoxic compost" and read the book titled "Compost utilization in horticultural cropping systems" by Peter J. Stoffella, Brian A. Kahn. You'll only get random pages, but it's more than enough to convince a person that, yes, indeed, unfinished compost does inhibit seed germination.

Here are the names of some of the phytotoxic compounds in unfinished compost; acetic acid, butyric acid, proprionic acid, valeric acid. Professional compost scientists say that finished compost is compost where bacterial activity has dropped to a low level and that's the safe compost.

In fact, they talk about raw compost, high in C content, as an effective weed suppressant because of its phytotoxic properties.

It's all the woofing and barking about nitrogen deficiency that's hooey.

That book costs nearly $200 new, but I might spring for a used one for $68.

Joseph R. Heckman, Ph.D., Extension Specialist in Soil Fertility; Daniel Kluchinski, Mercer County Agricultural Agent; and Donn A. Derr, Ph.D., Associate Professor, Economics and Marketing

"Observations of crops (including legumes) planted on soil to which leaves have been applied indicate that plants suffer from a temporary N deficiency unless additional N fertilizer is added."

I've seen N deficiency in wheat due to leaf application so I tend to believe it can happen.

Lloyd

Lloyd, your pictures showing a wheat field with two different applications of compost, one without grass added, and one with grass mixed in, is more than enough proof that Nitrogen was missing.

But the reason the field with the leaf-only compost was not green was not because the soil lacked Nitrogen, it was because the leaf compost was not finished composting because the compost lacked Nitrogen. While it was finishing composting after you spread it on the ground, the soil had the phytotoxic acids in it. I'll bet that if you spread that same leaf compost in the fall, you'll get a better outcome.

But the issue of seed germination is orthogonal to subsequent plant growth. Available Nitrogen for plant growth was never the issue when seeds failed to germinate in my garden beds loaded with compost. Seeds don't need fertilizer, they only need water.

It was the fact that the compost was still active that foiled seed germination. The ongoing bacterial activity was producing the phytotoxins. Your field with the purely leaf compost was in the same state; unfinished compost. Only when the leaves finished decomposing did that wheat really start to grow.

Actually it was not "compost", mature or otherwise, that was added at all. One area was uncomposted leaf/grass mix and the other area was uncomposted leaves only. No active composting was done prior to application, it was just raw feedstock dumped on the ground and worked in with a cultivator. Sure there was also a time differential but I've read enough from credible sources to satisfy myself that there was an N deficiency on that part of the field.

I suppose I could have added some N fertilizer but I wasn't willing to go to that expense for a few acres of wheat.

And it wasn't that the seeds didn't germinate, there was excellent germination in all areas of the field.

And trust me, if compost goes out of my yard, it's mature.

But we digress from the OP. It's possible there can be some issues with immature compost with some plants on some soils. Kinda wishy washy.

Lloyd

Lloyd, I appreciate you making the effort to argue the question with me. What I read in the excerpts from that book was extremely illuminating to me and I thought of you when I was reading that book. If it weren't so expensive, I'd buy you a copy because I know that you do more than just ponder the issue of compost, you actually do experiments and trials.

There were several lessons that I learned today. One is that unfinished compost is hard on root growth and will actually prevent germination. It's caused by the phytotoxic acids that are an intermediate compound in the compost process. Lack of Nitrogen will slow the compost process as will lack of Oxygen.

Second is that soil pH plays a big role in soil fertility. pH above 7.5 will inhibit Ammonium and Nitric Acid absorption.

Third is that the end product of composting, humic and fulvic acids, are mediums for availability of the various elements needed by plants. They bind to the Mg, Mn, Cu, Fe, Ca and other elements, as well as Ammonium and Nitrous/Nitric acid, and make them available for the plant.

For me, today was a good day, and this was a very productive topic. I learned a lot. Thanks to Lloyd, jbann, and fanfortony for their contributions.

Here is a link that might be useful: Good book about composting

Compost does suppress germination in some seeds while affecting other little. In my experience, garlic cloves, potatoes, beans, tomatoes, squash and various other cucurbita will not be affected. radicchio, arugula and lettuce will not be affected. Most herbs will not be affected, including tiny seeded thyme. I regularly start all these in compost trays, typically one year old leaves with kitchen scraps, cold composted in a pile, and sifted through hardware cloth.

beet, chard, and several daisy-type flowers will be affected some, Black Eye Susan dramatically so (very small seeds). Radish, brassica, parsley and carrots will be affected. Bok choi is probably somewhat affected. Generally, the smaller the seed the bigger the germination difference in regular soil cmp to compost. Hope this helps.

Thanks again to everyone for this fantastic discussion. I didnt realize I was "opening up such a can of worms". LOL. I have enjoyed the thread very much.

I have used the compost I make as a potting soil and for seed starting and have not seen any problem with the plants growing in either case. All that seeds need to germinate is water and the proper temperature. Some seeds need a somewhat warm soil temperature (tomatoes germinate better if the soil temperature is around 70 degrees and tomato seeds germinate very well for if the starting pot is placed on top of the refrigerator)) while others prefer a cooler soil temperture, peas for example. The one "problem" with using compost as a potting mix is that I need to add some periodically as it is digested, but the plants growing in the compost are doing quite well, blossoming and producing fruit, and very good tasting fruit.

IG

I'm going to see if I can find a copy of that book in any of the nearby libraries. It is a bit technical for my knowledge level but it seems to be a great book and I will try buying it if I can't find a copy anywhere.

Thanks for linking that.

Lloyd

Like Kimmsr, I use compost for seed starting, and I also get lots of unplanned volunteers in the compost pile. As long as the compost is finished or mostly-finished, it shouldn't be a big problem. You certainly wouldn't want to use "hot" compost with your seeds. :-)

As to the seeds themselves, as mentioned above a lot depends on the type of seed, soil temperature, and the age of the seeds. Many times older seeds take longer to germinate and have a less successful germination rate.

It's my understanding that carrot seeds can normally take 2-3 weeks to germinate; longer if the soil is too cold and/or the seeds are old. This is based on info I've read, not on personal experience.

Last fall I started a new compost area that was to be turned into a vegetable patch this spring. Having started it late in the autumn, there were only a few inches of organic material applied to the ground and it never got hot enough to fully finish. I turned it once or twice in April as the ground started thawing, and the grass clippings had very little deterioration; they were mostly intact and kind of mucky like grass clippings get when you pile them up. No additional material had been added to the area since last December.

But that didn't stop the volunteers of cucumbers, lettuce, and, lastly, tomatoes from germinating -- thanks to those leftover, unpicked fruits that were thrown in from the garden last October. [I'm used to tomato volunteers, but the cukes and lettuce were surprises.]

I can't really speak to experience with carrots (maybe I'll grow some next year), but there could be a number of factors that influenced low and slow germination.

All the best.

One thing that jumps out at me from this thread (and sometimes other threads on this forum) is that when we speak of "compost", even finished "compost", we may not all be speaking of the same product. Not all composts are created equally. I'm sure there must be some chemical/organic differences depending on the ingredients that went into making that "compost" product and how long it has aged.

I've never used straight compost in which to plant seeds but have had lots of volunteers in the cold piles.

Since using wood shavings as the brown in making hot compost I'm using it as mulch sometimes before it's finished. I fill a wheelbarrow with this stuff and wet it with alfalfa tea before using. Makes a very nice mulch. Not something I'd try to sprout seeds in but the mature plants are doing very well with it and it smothers weeds or makes them easier to pull.

One idea I like for veggie gardens is to pile the compost in between the rows and cover with straw as a walkway. Next season plant in that area and do the same with the new walkway which last season was the planting row. Gradually will improve the soil over the entire garden.

I think feeding the worms is a good way to improve the soil. All those tons of worm castings are the best fertilizer.

Thanks to all who posted good links - lots of great info.

Lloyd, I bought the used version of the book. 'Only' $68. If you're not able to get it from the library, I'll lend it to you after I've had a chance to read it.

I am seeing weeds starting to sprout in my garden beds along with the carrot seeds I had planted back in April. I'm guessing that the unfinished compost that was on that bed has finished composting and now seeds are able to sprout.

There's another lesson; to suppress weeds, use unfinished compost between the plants in your garden.

Oh Joepyeweed you really nailed it. I could not agree more. Then how does the forest deal with all the leaves that fall to the ground on a continual basis? Are they actually telling me that the earth tells nature to stop sending it more stuff because it is all backed up with old stuff and to start sending more just as soon as it takes care of the backlog? What do they mean that the soil can't do both? Man, I'm laughing so hard.

No doubt I would rather use fully composted material, but to say that the plants in my veggi garden will somehow be deprived of existing nutirents because the soil has to first deal with the uncomposted matter is absolutely absurd. I mean people please think about what you are saying before you say it.

Well for one thing a forest floor does not incorporate those leaves into the soil. They are deposited on top like a mulch, two different techniques.

What they mean is that if you take a high carbon material and incorporate it into the soil there will be a high liklihood of some nitrogen immobilization within that soil thus perhaps hindering quality plant growth. Thus soil has difficulty processing the carbon material and growing the healthiest plant. I've got pictures if you like.

Lots of credible sources of this information online if one can stop laughing so hard and look for it. If you can't find any, I suppose I could dig some up for you but it might have to wait until winter when I have some time to waste.

Sorry for being so absurd, I didn't have time to think about what I was saying. LOL

Lloyd

Lloyd,

Where can I get your address? The book came and I'm going to read as much of it as I can in the next few days. I'll be hosting a family reunion starting on the 19th through the 28th, so I'll shoot it your way for that spell.

Edit: Ok. I sent you an email.

Paul

Finished compost is finished compost. There is no reason to "cure" finished compost and if you need to "cure" the compost you make you are trying to use it before it is finished.
If you pile up your finished compost someplace where it will stay dry then it could last seemingly forever since in that dry compsot the bacteria that would digest it, in the absence of moisture, will go dormant. However, if you pile your compost out where the weather can work on that compost and it is moist and the bacteria are alive they will continue working on your compost, as it "cures", greatly reducing what you started with both in quantity and quality.

My sister is better at seed starting & I am better at composting.
So I let her start my tomatoes & peppers(hot & sweet) last spring. About 300 plants for 5 families, gave some away too. I ask her what she put in the seed trays. She said"Peat moss & blood meal". I can not prove it, but it looks like every seed became a trans plant.