planter
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Posts: 116
Joined: Thu Sep 11, 2008 11:34 am
Location: South Shore MA/ Z6?

VERY hard pack soil. What to do??

I am "prepping" three holes for tree planting next spring and I always dig a wide but not really deep hole. I propably end up at least 5X the rootball size and just a little deeper than root ball height and that's always worked well. :)

The holes I am currently working on have a VERY hard packed clay at only six or eight inches down. Would you be really aggressive in both size and depth?? I'm carving this stuff and I don't think root would be happy trying to penetrate it. :wink: :?

I'm thinking of going deep AND wide as wll as adding alot of compost and loam as well as the native soil. Maybe spread a full bag of gypsum over the bottoms of the holes?? What about crushed drywall. I have it but will it serve the same purpose as store bought gypsum?? :?:

Some of you must have to work with HARD PACK.. I feel like a scuplter..

I like to follow the outdated .50 cent plant and a $5.00 hole but just wonder how big to I have to go not having plantings sitting in a bowl..
Got anything good that's Z6 hardy?

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applestar
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Joined: Thu May 01, 2008 11:21 pm
Location: Zone 6, NJ (3/M)4/E ~ 10/M

I wouldn't dig a bowl in hard pack clay, ESPECIALLY when planting trees. They won't like sitting in a tub of water when it rains.

I fracture the soil with the fork -- it's best done after good soaking rain when the clay is damp but not soggy or you won't be able to get the fork in. Stand on it and teeter.

Now, when I do this, there's usually existing sod. I cut the sod in a circle that is about 3 times the diameter of the rootball, then cut a central circle the size of the root ball and remove the sod. fracture the clay underneath.

Oh dear I have to go... I'll come back and finish this later.

planter
Senior Member
Posts: 116
Joined: Thu Sep 11, 2008 11:34 am
Location: South Shore MA/ Z6?

The horns of a dilemma. :twisted: That's where this hole has put me. It's been just about an hour since I filled the hole with water just to get an idea if there is/was any drainage and it holds water like a fish pond!
I'm about a foot down and don't plan on going any deeper. This stuff could not be forked in a million years. It's more like carving. (sigh). :cry:

There must be a few of you that deal with HARD pack. Should I just plant high and go for a bigger diameter hole and bring what ever ends up in the hole to the right grade that way?

There is not enough Gypsum in the world to loosen this soil. Maybe I should mound it high now with partially finished but good compost with a topping of seaweed and topsoil and see if I can get a crop of worms in there to loosen up things before next spring.

[img]https://i402.photobucket.com/albums/pp102/planter_01/P1060269.jpg[/img]

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Got anything good that's Z6 hardy?

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applestar
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Posts: 28177
Joined: Thu May 01, 2008 11:21 pm
Location: Zone 6, NJ (3/M)4/E ~ 10/M

Ah. Just what I feared. I have an area like that that I HAVE converted into a rice paddy. It holds water for about 3 days without topping up under normally weather conditions. (Goes down a little faster in drought) Another area that I had hoped to turn into earth/clay-bottomed pond turned out to have just enough organic matter in the soil to be inefficient for holding water. :roll: Go figure.

So, I see and remember now that you said you have lots of rocks. I was going to say I use the sod as a kind of berm and build up a mound on TOP of the ground to plant the tree in. I get mixed clay soil from elsewhere in the garden (like that pond I was digging).

I actually don't have too much time right now either, but the way I do this, briefly, is to fork the ground, like I said -- just fractures or holes, layer leaves and about 1" of HALF FINISHED compost, usually teaming with earthworms. I lay the turned over sod from the center circle cut up in a few pieces as a buffer to put the tree on (the roots go on the clay soil side), and the sod from the rest of the circle to build a berm (you could use your rocks) Then use unamended clay/loam soil (I don't want to give the tree too rich a soil or it'll get "spoiled" and won't learn to live in the clay, but I've also inoculated the ground under it with the compost microbes and earthworms to hopefully start the conversion process) to fill around and up to the tree's soil line. I use the turned over sod on top of the roots (if bareroot trees) to hold them in place.

I dig a swale (crescent shaped moat) upslope or downslope of the mound depending on water needs of the tree (downslope if well drained soil is needed, upslope if sensitive to being dried out). Then mulch the surrounding area with cardboard or layers of paper topped with leaves, straw, and/or hardwood mulch.

Because the entire root ball and tree are sitting on top of the clay with just a mound of clay soil around it the tree WILL need at least 2, possibly 3 stakes around it with guy lines (is that the right term? I use rope threaded through pieces of old garden hose to prevent damaging the tree).

For trees that REALLY need good drainage, I add pea gravel or -- ummm can't remember the name of it but it's the coarse sand used for patio projects -- some with the compost and some on top of the turned over sod.

Oh! and VERY IMPORTANT, I fork/fracture all around the edge of the hole and also all the ground around the hole before mulching.

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