Amending soil - help please!

karewrenSeptember 15, 2006

Good morning! I'm about to head out to my latest gardening project and I'm procrastinating - mainly because I'm aware of what lies ahead...

Background info: 1) I've never gardened before moving to this property a year and a half ago. 2) There was no landscaping done on this property before I moved here. 3) Every time I go to plant a single plant it turns into a several week project of various stages once I discover what lies immmediately below the surface - hard dense clay under the lawn; a gravel pit of blue gray class A gravel around the perimeter of the house; a lovely grove of Japenese Knotweed on the NW side of the house; and a rock pile at the back. 4) I've dealt with the first three problems to various degrees of succes and I've "broken ground" in the rock pile for my latest project. 5) My entire property slopes at about 45 degrees (I may be exaggerating slightly) from the back of the house to the bottom of my driveway. My neighbour's property to the back (South)is about six feet above my back lawn with a sharp incline my side of their fence that comes down to my lawn about eight feet out.

It is here that I want to create my "Meadow garden" - a rather natural, rustic looking garden (made up somewhat of all the things I don't want elsewhere in my other garden plots) with wild flowers and straw flowers and daisies and poppies and the like. Fortunately, for the sake of erosion and having my neighbours lawn collapse onto mine, this slope is made up of rocks, lots and lots of rocks - big boulders, large and small stones and pebbles. Mixed into this is the driest dirt I've ever seen - it's hard like cement and breaks up into clumps that when I crush the clump the dirt is more like dust than soil.

So far I have "stragetically" placed a few of the large boulders here and there, dug into the slope somewhat. For the Campion, Evening Primrose, "Nearly Wild" Subzero rose bush, daisies, Rudbeckia, Coreopsis grandiflora, etc I have dug holes in behind the boulders or on a fairly "flat" spot, as big as I can, added lots of manure, good 3 in 1 soil, and bone meal and plopped in the plants. Behind each plant of course, instead of being flat ground, there is an inclined "wall" of dirt. I have a few more actual plants to move to this area - a Goldenrod weed from behind the shed, some Allegro poppies, and then some Carnation poppie seeds. I will follow the same plan with these plantings (except for the seeds, of course, which I will throw on a patch of ground that I dig up and amend as I do for the holes).

So my question is this.... around the remainder of the slope I want to lay newspaper (to block weed growth)overwhich I will dress with pine bark nuggets. Next spring I want to move some of the nuggets away and plant my wild flower and straw flower seeds intermixed amongst the already established plants. I'm sure they won't grow in the dry dirt that has not been amended, but I'm not prepared to dig up the entire slope and amend the soil 1) I don't want to disturb the integrity of my "retaining wall" and 2) I have a hernaited disc in my back and I just don't have the physical energy (or mental energy) to undertake such a task. So I'm wondering what I should do before I lay the newspaper/bark down that will allow for happy plants but be the least physically arduous on me.

I have peat moss, manure, black earth in bag fulls. Do I scratch the surface of the dry dirt throw on some of the PM, M, and BE and then cover with the newspaper? How does soil combine? Do I actually have to stir it up well or does mother nature do that with rain? Oh, and I'm a little OCD where rocks are concerned. Whenever I see one, I have to pick it up and collect it in a bucket for the next trunk load to dump. This scares me w.r.t the prospect of scratching the surface of the dry dirt in order to amend it because I know I will find 8,729,345 rocks under the surface. That's a lot of buckets!

Help! Thank you, so much... Karen

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bonniepunch(USDAz4 AgCanz5a)

I don't think you really want to go digging into that slope to remove rocks - you're going to contribute to destabilizing and erosion if you do that. Your slope isn't overly steep, but you don't want it eroding all the same. If you are finding a lot of rocks coming to the surface after each rain then that is a sign of erosion.

Wildflowers are good plants for a slope as they can handle the marginal soil and water conditions and many of them have deep roots. Amending your soil the traditional way is a problem for this area and those plants don't really need it much anyway.

One thing I would advise against is using large bark pieces for your mulch. These are likely to roll down the hill with a decent amount of rain or be pushed down with snow. They also don't break down to amend the soil which is something you sound like you do need. Shredded bark of various sizes would be a better bet. As it breaks down, worms will eventually move this new rich soil down to the rocky clay stuff. It takes awhile, but it is a thousand times easier than digging amendments into a rocky slope!

Newspapers to smother the weeds are an ok idea, but they won't break down on a slope as well as they would on flat ground, and they might just slide off. Putting down a layer of shredded bark mulch three inches deep in the areas you want to kill off the weeds will be just as good if not better at weed killing and soil amendment.

Planting things in behind rocks as you say you have been doing is a good way to give the new plants a secure spot to develop. It'll take two or three years for that slope to fill in nicely, so don't be impatient and plant things too close together!

One thing to consider would be terracing the slope to some degree. If you have a lot of big and medium sized rocks, make little arcs of walls about 6" high and fill in behind them with your peat moss, manure and black earth. This way you can plant some larger shrubs or plants that require a slightly better soil.


    Bookmark   September 15, 2006 at 12:02PM
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casper1(5/6- -10F Ont)

Before going any further, I suggest "google" lasagna garden, a lot of your questions will be answered there. Rai

    Bookmark   September 15, 2006 at 12:25PM
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Thank you so much BP for your detailed and understandable response. I had thought about putting in a specimen tree or two but wondered about the destabilizing affect that would do to the "wall" from the size of hole I would need to provide for the tree. I have gathered up a huge pile of large stones (slightly smaller than, say, a football; larger than a softball) that I could use for your idea of a terrace. However, I wouldn't want the stones to show in the final appearance - could I sprinkle some dirt on them and then some mulch to cover them up if I terraced the arc in a slope as well? Any suggestions, given the nature of the look I'm going for, of a specimen tree? (I already have a Mountain Ash, Smoke Tree, Dogwood, Crismon birch, Yew, Weeping Pea, Weeping False Cypress, Jackmonti birch, cedars, dwarf alberta spruce, fat albert blue spruce, and lilacs elsewhere on the property. Maybe a Japenese maple - the one with the feathery leaves; I've been wanting to find a spot for one of those, but they are pretty expensive too!)

And actually, the gardening centre was out of all mulches last night when I picked up the Pine bark nuggets (wouldn't have been my first choice - but the look was sympathetic to my end goal). I'll check out some other garden centres to see if they have shredded bark mulch.

Thank you for all of your help! It's such a mental relief to get some feedback on this!!


    Bookmark   September 15, 2006 at 12:32PM
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Actually, I got the idea of the newspaper from reading through other forum Qs and read something about this "lasagna" garden. Thanks for the reminder, I will check out more info on it! K.

    Bookmark   September 15, 2006 at 12:36PM
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bonniepunch(USDAz4 AgCanz5a)

I would be really hesitant to build a lasagna garden on a 37 degree slope - especially in NS where the soil can get pretty waterlogged at times. It will slide down. Lasagna gardens tend to encourage roots to stay in the amended zone for the first year or two (roots would not want leave this nice rich soil for a rocky, likely compacted area), and karewren needs the roots to go into the slope to discourage erosion asap.

On a flat bit of ground they are a good way to build a bed with minimal effort, but they aren't perfect :-)


    Bookmark   September 15, 2006 at 12:37PM
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bonniepunch(USDAz4 AgCanz5a)

Terracing it is a lot more work, but the end result is something that I like a lot. It is also something that can be done in stages - make each arc as big or as small as you want or have the energy to do. Everyone has a different opinion on what they think makes a nice garden however, so I would suggest you web surf on terracing and/or check a few books out of the library to get some different ideas on how the end results might look.

A Japanese Maple would look beautiful in such a spot, but it might not be practical. Slopes have a tendency to be tough on plants because of poor soil, lack of water and because they are cold. Cool air flows down them and pools at the bottom, so you have to select plants that are not marginal for your zone. Many Japanese Maples are only just hardy for your area, but there might be one or two that would tolerate a cooler slope (I don't know much about Japanese Maples, so I couldn't recommend any specific ones). A smaller one rated for USDA zone 4a or 3b or Ag Can zone 4b might adapt just fine - check the labels when you buy - many nurseries use tags printed for the American market and those use American zones - a USDA zone 4 is roughly equivelent to your zone 5 (ish? not sure where in NS you are). Also, many non Japanese Maples have shallow root systems - you might want to read up and see if Japanese Maples do too.

Dwarf Forsythias would be an excellent choice if you like them. Junipers are also great.

One suggestion to hide the rocks of a wall if you don't like the look of them is to fill up all the loose cracks and grow thyme or some other cascading plant over them. It will root in all the soil in the cracks, and both hide and secure them.


    Bookmark   September 15, 2006 at 1:04PM
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Not sure where you are in NS, but if you're near Halifax, just grab the phone book and call for the mulch prices and contents. Also, fall is coming up and I'm not sure if you have access to shredded leaves, but they are an excellent mulch - they stay put on my slopes and amend the soil at the same time. They invite worms!

I can empathize with the rocks and the slope. BP's advice about not destabilizing the slope by removing too many of those rocks is so right!

You might also like to place some 'stepping' areas in your garden. After tackling a slope 5 years ago, I realized that I had omitted 'stepping' places, and placed some in the gardens the next year. I'm not getting younger and am thinking of the future when doing splits in the gardens will not be as easy.

You might also like to put some 'bones' in there such as a birdbath, feeder, etc. These are nice, especially in a garden such as the one you are creating.

Sound like a great garden in the works!

    Bookmark   September 15, 2006 at 8:51PM
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