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Sat, Aug 6, 11 at 14:50
| I could really use some other opinions on this problem. The gardens I tend were created in the mid 90's. There are 6 borders, some of which are 200 feet long by 15 feet deep or more. These borders are highly maintained and are densly planted with small trees, medium and small shrubs, and literally thousands of perennials and bulbs. My problem is this: these gardens have been mulched with pine fines for so many years that now the native soil layer lies anywhere from 6inches to 10 inches below the surface. Newly planted shrubs seems to do okay, but any new perennials and especially groundcovers can barely survive. If they do somehow root into this mulch layer, they are so susceptible to drought and they almost never spread. Many just refuse and die. I've composted instead of mulched for 2 years now- just topdressing 2 inches with mushroom compost, but that certainly isn't going to fix the overall problem. There really isn't any way to remove the mulch without damaging or destroying the garden. Is there anything I can do to make the pine bark break down faster? Is there some magical cure for a garden this big that has its soil essentially buried? Should I switch to hardwood mulch, or never mulch again? Do I really have to lift all of the plants (perennials at least), remove this layer and bring more soil mix in? I've been thinking about this for over a year and can't come up with a game plan. Would love to hear some opinions! |
Follow-Up Postings:
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| I await responses and solutions to your problem as I have similar situation. My beds are also heavily mulched, except with freebie wood chip from tree companies instead of 100% pine fines. So far, I have no problem planting annuals in those mulch. Impatiens have been doing just fine. The holes for each impatiens were 3 time the size and filled with compost, so the plants are basically sitting in compost surrounded by wood chips. |
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- Posted by beeman_gardener 5 (My Page) on Sat, Aug 6, 11 at 22:04
| Can I suggest Activated Compost tea. This should add the bacteria and microbes which will help break down the mulch must faster than without. I use leaves around my fruit trees, then sprayed down with ACT a couple of times, by fall all the leaves have been incorporated into the soil. Another point. Pine fines will slowly acidify the soil, which might be some of the reason plants are failing, the .pH is off what you really need. Suggest a soil test, then do some amending. |
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| Thanks for the suggestion. I will look into AACT as I don't know a whole lot about it. But anything that will speed the breakdown of pine bark would certainly help at this point. I have done Ph tests on various areas in the garden and have corrected those problems, though there could still be some issues here and there. I think alot of my problem is simply that these smaller plants have no access to actual mineral soils. Even the compost I've added over the last few years has simply been "swallowed" by this mulch layer. Any other comments would be appreciated! |
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| Have you contacted your local office of the Virginia State University Cooperative Extension Service about having a good, reliable soil test done? |
Here is a link that might be useful: VSU CES
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| It sounds like too much mulch to me. I maintain about a 3" layer in my landscape beds, and don't add to it unless it needs it. How did yours get so deep? Did you just keep adding mulch to it, even when it didn't need any? I would think you'd have some rot issues with the original planting that are in the original soil. Having that much mulch around the trunks/bases is not a good thing. Personally, I think it's time to get down & dirty and start removing it until you're back to an adequate level. I would venture to say that there will be people lined up for miles that would take the pine bark fines over in the container gardening forum. Joe |
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| Normally I scrape the mulch away when planting new stuff, so the roots go in the actual soil, and then replace the mulch. But it should not have gotten so deep. Mulch should be replaced as it breaks down to maintain a somewhat constant depth. But what to do now, is what you want to know. Yes you need that mulch to break down, you are right that you can't remove it. I would add nitrogen. Blood meal is a good fast acting organic nitrogen, but any lawn fertilizer will work too. Pine bark is low on nitrogen as well as acidic so correcting the pH as best you can while adding nitrogen should speed things up. Topdressing with mineral soil and mixing it in lightly would probably help too, once you get the pine starting to decompose. You've already got plenty of organic matter in the pine, no need for more. The compost tea is a good suggestion too. I mulch with tree chips like toffee-el does, but I don't add more every year. I topdress with things like compost, rabbit manure, mushroom compost. Those feed the soil and need replenishing every year. I scrape back the tree chips so the compost etc. go on the soil. Around here people mulch with ground up bark dust, from the lumber mills - douglas-fir and hemlock mainly, that's what we have here. Awful stuff, it's literally a flour or dust it's so fine, and the fibers are itchy as all get-out if they get on you. And they'll dump it on their gardens every year like clockwork and get the same thing you have now - several inches piled up, and water not penetrating to the soil so all their plants suffocate and dehydrate. It's called 'beauty bark' but there isn't anything beautiful about it. It's probably in groundskeepers' contracts that they must add beauty bark every year. Tree chips are way better, they don't pack down since they're in larger pieces, and they allow the soil to breathe and water to penetrate. |
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| The pine fines that have been used in this garden sound a bit like 'beauty bark'. The garden is on tour every year and so it always gets mulch whether it needs it or not to achieve that 'perfect' or 'finished' look. I've only been on the scene for a few years now and have mulched minimally- a dusting so to speak, but have always known that the mulch is a huge problem that needs to be thoughtfully and agressively addressed. I like the idea of removing as much as I can without damaging the existing plants even though I may only get 1" out. Then using either nitrogen or AACT to help speed decomp and then follow up with a mineral soil topdress. Does this sound reasonable? I just got back from Chanticleer and Longwood Gardens where they only use leaf mold as a mulch and very little at that. The problem in my garden exists because its just been mulched every year regardless of need. I don't have a rot problem because the pine has become almost hydrophobic and doesn't hold any water. I wouldn't mind removing the whole layer, but it would be impossible with the number of plants that are growing there- there would be way too much root damage, not to mention the insane amount of labor it would entail. So, what do you all think of my above mentioned plan? |
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| Adding nitrogen isn't going to help all that much. Pine bark contains a high amount of lignins, which resist the bacteria that causes decomposition. No sense in feeding the bacteria nitrogen if the bark is resisting it. The lignins in the bark are what make it a desirable mulch, because it lasts longer, and doesn't decompose much, thus not tying up nitrogen. This is the main reason people use it to make Al's 5-1-1 mix. It is also the reason it is sometimes sold as "soil conditioner". You can till it right into soil to improve drainage, and not tie up nitrogen. I would kill to have a bunch of your pine fines, and if I was near you, I would gladly help in the labor to remove it. Unfortunately, I am in Wisconsin, and pine bark fines are hard to come by around here. I have to buy bulk pine bark mulch and sift it to get the fines and smaller pieces to use in my veggie garden. I still recommend trying to remove as much as you can, and do NOT add more. If you need it to look fresh, you're going to have to fluff it up rather then top it off. Joe |
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| This is why I like compost mulches. They're nourishing and quick to break down. |
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| Thanks Joe. Makes sense. I'm going to look further into AACT to see if thats something that might help speed decomp of the pine fines. I wish you were nearby- I would gladly give you all of it! In the meantime, I'll work on removal this fall and try to find a weed-free topsoil (is there such a thing?!) to do a little topdressing with. |
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| Advertise your pine bark fines in the container gardening forum. People over there are always looking for pine bark fines, and you may even find labor help. I believe quite a few people are from Virginia. Joe |
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- Posted by tsugajunkie z5 SE WI (My Page) on Mon, Aug 8, 11 at 2:15
| I would think the lignins in 20 year old pine bark fines are breaking down and tying up nitrogen. Plus, the odds of such large beds, over 20 years old, being 100% pine bark are slim, I'm sure plain old wood is in there as well. I would add N not to speed up decomposition but to help feed the plants. A soil test will help see other needs, but is somewhat unreliable for N. tj |
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| Well, there is soil in the beds- they were very purposefully constructed. The problem is that the soil lies far below the surface. I've cored many different areas and can easily see the pine bark horizon and it is many inches thick. Some of it is breaking down, yes, but shallow rooted plants don't thrive in in this layer. I've tested the soil many times and have to look more closely at my Nitrogen numbers, mostly I've been looking at Ph. |
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| Hey laulau, sounded like you have a really nice garden. Any pics? |
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| I'm pretty sure the lignins are not broken down, because the pine bark fines weren't put in there 15 years ago, and left to sit there all these years. From the info of the original poster, it says that pine bark fines were added every year, whether needed or not, for the last 15 years or so. Maybe the very bottom is broken down a bit, but the whole pine bark layer is likely not. I think adding nitrogen is not going to give you any results in the near future. It sounds to me like we're looking for a solution in somewhat short order, and that still leads to manual removal of some sort. Joe |
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| I would love to post some photos, but alas, I've spent too much time in the garden, and not enough time figuring out how to post images to this site! Another follow-up question: I want to use some topsoil here and there to level some areas and as a topdressing to cover exposed roots after I remove the top layer of this mulch. The topsoil around here is actually really nice, but its loaded with weed seeds. Many bagged topsoils I've found don't really contain mineral soil, but sand and compost and some even include pine fines which I definately don't want. I found a bagged soil which says its loam, sand, and compost. I hate to use bags, but I do really like the consistency and darker color that you often get out of bags. Any comments on this? |
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| Some kind of fungi that likes dead pine might help digest the stuff. Perhaps a fungal-oriented compost tea would help. If you have some rotting pine wood somewhere maybe you could use it to inoculate your mulch. The soil test suggestion is always good advice also. Keeping the stuff moist should help although difficult to do with such fine material. The book "Teaming With Microbes" might be helpful. Does your mulch have any worms? |
Here is a link that might be useful: Teaming With Microbes
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- Posted by yumtomatoes 10b/FLA (My Page) on Fri, Aug 12, 11 at 14:39
| So in 15 years the pine sitting at the bottom of the mulch layer hasn't yet decomposed? |
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- Posted by butterfly4u 8 (My Page) on Wed, Aug 17, 11 at 22:53
| Laulau, Physical removal is your only option. THe trees, shrubs and plants are smothering. They can't breathe! I am surprised you aren't noticing some of the trees and shrubs dying. It's a dirty job, but somebody's got to do it. Good Luck! |
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| Thanks for all of the advice. Yes, ordinarily you would think that the trees and shrubs would be suffering at this point, but pines fines are so "fine" that the movement of water and air is never a problem. Also, this larger material was likely planted when there was still real mineral soil close at hand. There doesn't seem to be too much mulch built up around the collars or crowns of these plants, at least not enough to hinder thier growth, but there is MORE than enough to prohibit normal growth of perennials and groundcover. Its near impossible to get these to establish properly towards the front of the beds. Plants that spread by runners or rhizomes or never have access to actual soil- they just hang on as long as they can in a mixture of pine bark and a bit of compost that I've incorporated over the last few years. So, I'll just remove as much as possible i suppose and maybe even topdress with mineral topsoil. |
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| We Horticulture gardener( here in S.C) turn the old mulch before adding new much to the beds, Shred leaves, instead of just raking them into the nearest bed. I would remove all the mulch & shred it. Remove the Perennials, turn the shredded mulch into the bed, then plant & mulch. You should do this a bed at a time. Sounds like someone needs to compost yard waste every year. |
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