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clay soil, new flower bed

Posted by laura_new_gardener 5 (My Page) on
Tue, Jun 20, 06 at 12:17

I've tried starting a new flower bed in our sticky clay Indiana yard. Last summer we killed the grass by covering it with a thick layer of wood chip mulch. I have so many questions! The soil is dense and sticky when wet, hard like cement when dry. Would you classify this area as "poorly drained," since some plants do well in that situation? Can I fix it by renting a tiller and tilling sand or peat moss into it? What do I do with the wood chips, remove them before tilling or till them in as well, hoping they rot into the soil by next year? Is there any other way besides tilling to get around this problem? I had $100 worth of new plants die after I planted them in this flower bed. The daylilies that are blooming are smaller than everyone else's in the area.

Follow-Up Postings:

RE: clay soil, new flower bed

I would definately till in as much compost as you can get your hands on. I would also add sand but I dont know how much. I dont think I would would add peat.If I remember right it holds moisture and your trying to get rid of it. You can go to hgtv and click on "gardening by the yard", I'm sure there was a program on this subject.

RE: clay soil, new flower bed

The basic run down on improving soil like that is as follows:

1. Add about 2" of compost over the entire area. If you wish to till, then use about 4" and leave 1" for top dressing.

2. Cover the entire area with an organic mulch such as wood chips, but prefer the smaller pieces as these break down and add humusy material to the soil faster.

3. Plant.

If this doesn't correct the soil enough to have plants survive then bring in screened, non clay based topsoil and raise the area 6", add a couple inches of compost and mulch.

RE: clay soil, new flower bed

OMG, no sand, please! That's the absolute worst thing you can add to a bad clay soil. Organic matter and plenty of it!

RE: clay soil, new flower bed

One can use gypsum to "loosen" clay soil. I've experimented with it, and it did work in a heavy clay site, for about 8 years (well, that area is still draining well after 25 years, but...). The catch is simply that while gypsum will help the soil texture, it is effective only within the applied area, thus water will drain to the bottom of the improved site, but then drains *very* slowly or accumulates on top of the un-improved clay base. One must prepare/dig very deeply [or work on a slope] to allow enough area for the accumulated water to percolate from the bottom of the bed without saturated the root area of your growing plants.

Personally, I prefer to use raised beds made by the lasagna method because: raised beds inherently have good drainage; the lasagna method gives a very good soil in a short time (you can actually plant annuals immediately in the raw/cooking lasagna); and a properly-based lasagna will smother almost all weeds that may have already been in the chosen site. Oh, and home-made lasagna may be high-labor, but it's NOT expensive -- something consider if you have a budget (or a love of new bulbs, lol).

RE: clay soil, new flower bed

I too am in Indiana, and have clay. Just because it is sticky when wet, and like a rock when dry doesn't necessarily mean you have poor drainage. Is the ground around the area squishy after a heavy rain?

What I have done sometimes in the past, is to spray an area with Round-up, and make sure it is killed off really well...usually totally brown after 2 weeks. Then I put down brown cardboard (or layers of newspaper will work too), and then mulched really well. I use the free tree trimmer mulch on the bottom, and dress it up some with some finer darker purchased mulch (also bark) When I go to plant, I scoot back the mulch, cut the cardboard if need be (or remove paper), dig an oversized hole for the plant, and then use some combination, of purchased top/potting soil, and water in well.

It is so great to have an area all ready to receive plants, and is weed free both b4 and after planting. Then, just to be sure, I PREEN the mulch, as weed seeds will blow in and germinate in it too.

Hope this helps.


RE: clay soil, new flower bed

What is the lasagna method? I am starting a new perennial bed - getting rid of patchy grass and planning on planting slowly but surely. I've been covering the area with old rugs to kill off the grass and then plan to start digging it in - I too have very hard packed clay soil - but there are some earthworms in there so I have some hope.


RE: clay soil, new flower bed

Fern, you can get the basics of lasagna aka interbay mulching here

It is basically using alternating layers of greens and browns to 'sheet compost'.

The term is used very generally though and often means nothing more than covering the ground with several layers of newspaper, cardboard or any other organic material to prevent weeds and grasses from growing through it. On top of this might be compost. It could be any organic matter that will break down over time and become compost. Often a mulch of some sort is placed on top of everything.

Lots of folks doing basically the same thing with variations in what they use and how they go about it.

It kills existing vegetation (like your using carpet does) and enriches/conditions the soil at the same time.

No need for tillers or shovels or sore backs.

RE: clay soil, new flower bed

Personally, I don't think a single layer of paper or cardboard covered with mulch is lasagna -- I don't think edible pizza is edible lasagna either, for the same reason -- it's takes at least several repeating layers of differing ingredients to make lasagna :)

The Interbay article is interesting, but as it says, Interbay Mulch is just another version of lasagna or sheet composting. Unfortunately, I go back far enough to remember the original Rodale's articles on sheet composting (1950s?) -- and my parent's comments that SC had been done by the better gardeners of Europe for hundreds of years.

However, the important point is that it doesn't really matter what you call it -- layering of various fresh and dried organic materials, kept dampish, and topped with a light-blocking cover (whether of burlap or shredded leaves or another type of mulch) *does* make an excellent soil, and quickly.

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