Well, today I did a bit of landscaping around my home. There was one strip on the side of the house that had been covered in lava rock, and underneath that was some old rotten plastic strips underneath the rock. Must have been there for 30 years or more. Anyway, after I removed all this gunk, I discovered some really compacted clay soil. No worms, just a few centipedes frantically running around looking for a dark place to hide again. Anyway, I broke all the clay up and now here I am tonight with an aching back wondering what I've gotten my self into? lol. Boy, this clay really needs some serious ammending. It's in a nice sunny area perfect for gardening. If only I had some decent soil. I'm willing to work hard at this, so if any of you have ideas/suggestions, I would love to hear them. This area is about 5'x30' long. Where do I begin? Thanks everyone.
Rake it out smooth and cover with 4" of wood chips, wait for it to soften. Plant clay soil adapted plants after it aerates and mellows. It may take some months for it to be ready for planting. Or dig the clay-like soil out and replace with looser soil, plant in that. If there is room to go up, you can instead place looser soil on top of the clay and plant in that, without mixing the two together. This avoids having to dig out and dispose of the existing soil. Concrete blocks or stones can be used to hold the new raised bed in place. Going up also results in a soil that becomes 10F warmer in summer - thought to improve results with warm season vegetables and other warmth loving plants. Carl E. Whitcomb reported in Establishment and Maintenance of Landscape Plants (1978 (1991), Lacebark Inc., Stillwater) that silver maple and Chinese pistache planted in amended planting holes in clay loam and subsoil clay grew better without amendments: "Plants with no soil amendments were consistently larger than those with soil amendments" He concluded this section with "there was no 'magical' treatment to make a poor subsoil clay into a productive soil". Small liberally amended areas surrounded by existing soil of markedly different texture may collect water during wet conditions (winter) and shed water during dry conditions (summer). This is why trees (and shrubs) in amended planting holes do not grow as well as those planted in existing soil on the same sites. If you can provide a modified area that is big enough to accommodate the entire potential rooting area of the plants chosen for many years then amending/replacement of the soil can work. This is most feasible with dwarf plants producing limited root systems such as miniature roses and alpines, or short-season plants like annual flowers and vegetables. Plants placed in a generously sized (for them) bed do not have a zone of different texture right next to them, where they are immediately exposed to water seeping in from the sides or being wicked away during the summer. Of course, if a site is so damp that a prepared bed floods during winter then drainage pipes will have to be installed or the plants will have to be grown in raised beds.
Thanks Ron, I think I will dig some of the clay soil out and add some new soil. Thanks very, very much for your helpful ideas again. By the way, where can you get some wood chips?
Thanks Ron. I will do that. Also, I was thinking of adding some shredded leaves in the fall. Is there a way one can shred leaves without purchasing an expensive machine?
I wouldn't mix anything in. If you are talking about putting leaves on top, as mulch, just rake them onto the bed.
You can shred them with your lawnmower. Just run back and forth over them. A bagging lawnmower would help. Do it as many times as necessary.
Most all trees do better, if amendments are not added. Here is a link to working with clay soil and to clay soil amending. - Millet (1,381-) http://www.bachmans.com/tipsheets/Soils/WorkingWithClaySoil.cfm
Ron, a further question or two on this topic (I have the same clay soil issue as the initial poster): I recently dug out a dead azalea (having been dead for two seasons now) and under the root ball (about 8-10 inches under the soil) I found compacted clay and small rocks which I could barely chip into. At first I thought it was someone's paving stone because it was so hard. I currently have rhodos and cornus alba doing well in that bed, but all three of my azaleas have died since being put in by the builder 5 years ago. I was hoping to plant some part-shade perennials (hostas, heuchera) in the bed, since it has a lot of bare space now. Given that I don't want to dig the entire bed up and disturb the rhodos and dogwoods, would the existing 8-10 inches of loose/good soil be enough for perennials? Is there anything I can do to try to "fix" the clay which is already buried in the places I want to plant? (I'm assuming that wood chips should be placed directly on the clay in order for them to do any good). Finally, if I were to add a couple more inches of soil to make a slightly more raised bed, would I have to dig out and raise the rhodos and dogwoods? Or could I just mound some soil where I am going to add the new plants? Thanks!
My back yard and for that matter most of my yard is nothing but clay once we dig down 7-8 inches so when I wanted to make flower beds we dug up the clay and removed some of it and added compost of all sorts ( we're fortunate to have a compost site at our landfill site). After a couple of years I was able to plant most plants into the ground and not in raised beds. I notice your in Abbotsford, I have family there and they tell me the soil is much like ours out here in Nova Scotia.
They told me at the nursery to work some peat moss into the clay concentrated areas, and that this would work to break down the clay, over time. It really worked for me, because the clay had become less compacted and more like a dark rich soil, the following season. I always practice this now, if I come across clay - I work in some peat moss. If the clay goes deep, then I work the peat moss in deep, too. I guess every gardener has their own way of doing things - this is just my way, and it works. Enjoyed reading the other suggestions though, as well. : )
What worked on our clay soil was to lay cardboard down and pile grass clippings on top. Next season it was workable and I amended with compost.
What I did, was to add 30% sand and 20% silt, if you are lucky enough to be able to find it. Dig in leaves and plant red clover. Turn the soil over annually. Eventually it will turn to loam. you will find the earthworms are extremely important here. lots of leaves in the fall will feed earthworms +++. you will end up with a most amazing clay loam in about 3 years. This region has areas of pure silt, pure clay, and pure sand, due to being in the vicinity of the Great Lakes, and ancient huge waterways.
