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northwestbirdluver

Amending compacted soil

20 years ago

Hi,

I have a shady flower bed on the north side of the house. I've had problems with the soil being compacted, which makes it harder to pull weeds out, for one thing. The plants I have there seem to be doing all right. However, moss often grows underneath some plants, and it's hard to remove it from beneath some smaller plants without hurting them. The same thing with grass.

I would like to redo this bed. What can I do to improve the soil? Should I buy garden soil and put it over the existing soil? If so, where is the best place to get quality soil? Or should I add lots of organic matter (such as bunny manure)? I have tried mixing bunny poo into the soil before, but it didn't seem to help. I may not have put enough in, but I wasn't sure how much to use.

Thanks in advance for your suggestions!

Comments (20)

  • 20 years ago

    Mulching would take care of it. Covering the soil so it is protected from the atmosphere makes it much slower to dry out. This results in it becoming softer. You can even take mineral soil that is like concrete and get it to soften by mulching it with wood chips. Some places have tall forests growing over terrible soil because the climate permits it. After an adequate layer of organic litter develops even large trees can grow.

  • 20 years ago

    Thank you very much for your advice!

  • 20 years ago

    NWBL,
    mulching with chips or sawdust is a good idea but keep in mind that more nitrogen fertilizer will be required to replace that which the decomposition process takes from the soil.
    Bark dust works good too but any of these will further acidify your soil, thus, plant requirements may necessitate adding lime or another "sweetener" may also be necessary.
    Fritz

  • 20 years ago

    I've heeled a pale rhododendron into a comparatively fresh, still warm wood chip pile and had it green right up. Have also mulched with wood chips for years without seeing a pattern of consistent yellowing after mulching.

    Here is a link that might be useful: Myth of Pretty Mulch

  • 20 years ago

    The issue of nitrogen depletion with wood-based mulches is minimal when these are used only as a mulch or topdressing. It becomes a bit more critical if these types of products are worked into the soil. And there is far less of an issue with woody material affected by this temporary lack of nitrogen than there is with finer and more shallow rooted plants like perennials and annuals. There is also virtually no affect of bark or wood mulches significantly altering soil pH. Slight differences may be noted with very fresh material but it would be very temporary and quickly buffered by the existing soil conditions.

  • 20 years ago

    Thanks for explaining that for me, gardengal. Is pine needle mulch a good mulch to use? The soil under my Douglas fir tree is very good, so I was wondering if needles would improve soil in my beds, too.

  • 20 years ago

    This is a really interesting thread. I don't know what "Arborist Wood Chips" are. I have a veggie garden where I want to amend clay soil and am thinking that I could use wood chips, or shavings, or chippings from a professional outfit that chips trees at least for the pathways and for a fallow area. It seems tht most of this stuff is quite big though and would take years to break down. I also used bark mulch on a flower bed and all of the plants were yellow, so I presume that I need nitrogen there. Do I just scatter nitrogen fertilizer over top of the bark mulch?

  • 20 years ago

    Pretty much any organic matter can make a decent mulch and as it breaks down and decomposes, will enrich and improve the soil. The larger the particle size, the longer it will take to break down. Pine needle mulch (aka pine straw) is not as common around here as in other parts of the country as there are not that many pines around. If you have it, use it. Doug firs tend not to be as noticeable in their needle drop - I rarely see any in my garden - but they do shed copious amounts of what I call flower casings for lack of a better and more botanically accurate term (I'm sure someone will jump in and correct me :-)) I sweep up buckets full of them from my patio, walks and roof each season.

    I personally use a bagged mulch - my preference is Gardner & Bloome Soil Building Compost, a wonderful rich and dark weed-free product that will continue to feed the soil while conserving moisture and suppressing weeds.

  • 20 years ago

    Under my two Doug firs, there are lots of needles, as well as twigs and other debris. One of my neighbor's has big Cedrus deodaras, Norway spruce, and hemlocks that overhang part of my yard. There are piles of needles in that area (the trees have been there for years), so I have lots of free mulch. I just scooped up a bunch from each area and put it in a big pot, and spread it around the area. It already is helping, because when it rains, the water doesn't puddle so much. The bed looks so much better. I haven't decided what to plant there yet.
    Thanks again for your help.

  • 20 years ago

    I'd add as much organic matter to your soil as you can, and then mulch to boot.

    I use alfalfa pellets around all my roses about now (though I have not done it yet this year) and also add llama manure around all my plants as well. I like the llama manure because I can use it without composting it, but any composted animal manure will work. I just push my mulch aside and topdress with it. I'm too lazy to work it into the soil... that's what worms and rain are for.

    Anyway, then I use wood chips or shavings for mulch. You can get them really cheap from sawmills (delivered even) if you have room for a whole truckload. I can't remember exactly how much it cost me, but I know it was under $150 for a huge semi truck load of wood shavings from my local mill. It is lovely to have plenty of mulch just waiting to be spread when I need it.

    Also... some places you can get shredded trees and yard waste for free. I know of a place where they just dump it by the road and it is free for the taking... but the gas for my truck and the pain in my back isn't always worth it.

    I've only been at my place a few years now, I have rocky clay soil, and I have really seen an improvement where I have been doing this every year.

  • 20 years ago

    Thanks for your input, madspinner.
    I think I'll add some bunny manure to some of my beds this spring. My vegetable garden's soil could use a little enrichment, too.

  • 20 years ago

    Hello again. At the nursery where I work, they have some of that Soil Building Compost you mentioned, gardengal, and I was thinking of getting some for that bed and another bed with poor quality soil (it isn't compacted, but it's light and kind of dusty, and doesn't drain very well). However, I was concerned about the "lime to adjust soil pH" that it has in it. I'd like to plant a Daphne; don't they prefer a more acidic soil? Is there a very significant amount in this product that it would affect the daphne's health? I don't want to make the soil too "sweet" for the daphne, if I get one.
    Are there any other good brands of compost that don't affect soil pH too much? Acidic would be okay, though, I guess.

  • 20 years ago

    I have another question. If I plant something and add the compost on the top and spread it throughout the rest of the bed, how long will it take for the compost to start "working"? Since the plant prefers good drainage, I'd be concerned how it would fare while it was waiting for the soil to be improved. Should I place the compost in the bed ahead of time so it will already be "working" by the time I plant?
    I'd like to plant a 'Gulf Stream' Nandina, and eventually maybe a compact, spring-blooming Daphne.

  • 20 years ago

    Also see the attached thread.

    Here is a link that might be useful: Drainage amendments--PDX?

  • 20 years ago

    Also see this thread.

    Here is a link that might be useful: Best soil amendments for northwest

  • 20 years ago

    What kind of plants are you growing in your beds, nwbl? I have a bed with a Daphne and also have a Campanula pocharskyana there that covers the soil completely so there is no need for mulch. In another bed I have some Heucheras and mini roses by a deck, and there is moss growing under them. I encourage the moss as I like the look of it and it inhibits weeds.

  • 20 years ago

    The plants in the compacted part of the bed has candytuft, rockcress, lupines, a miniature rose, Blue star creeper, and violas. The entire bed isn't like that. One part stays moist and is compacted, and the other corner stays drier and isn't as badly compacted.
    I have another bed with light, dusty soil that looks sandy, but the drainage is not very good. That is where I want to plant a Nandina and a Daphne, which is why I need to add some compost there, as well. The other plants in that bed include Bluebeard, Echinacea, Penstemon, asters, coreopsis, and lavender (which I don't think would like compost).

  • 20 years ago

    Gardengal, I think "catkins" is the proper term for the flower casings shed by Doug Firs. ;) ;) ;)

  • 20 years ago

    This is a very useful thread! My soil ranges from dusty to heavy/compacted. I have been using bark mulch (mostly to keep weeds down), but am now wondering if this will effect water absorption too much in my non-buried soaker hose beds. Hmmm.....

  • 20 years ago

    I didn't think conifers had catkins. Oh, whatever. Mine actually do shed NEEDLES, anyway, not pieces of the cones.

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